C03C - MATERIAL GUIDE - CARPET

C03C-1 Carpet Fiber
C03C-2 Carpet Construction
C03C-3 Carpet Construction Methods
C03C-4 Carpet Performance
C03C-5 Preparation Materials
C03C-6 Underlayments for Carpet
C03C-7 Carpet Cushion
C03C-8 Carpet Adhesives
C03C-9 Carpet Accessories
C03C-10 Carpet Bases

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Preface:
This study guide covers commercial and residential carpet and related materials and their recommended uses. Specifiers and/or persons selecting such products should verify all facts relative to the particular project requirements.

To fully understand how to choose the most appropriate carpet for an institutional, commercial, or residential project, a thorough knowledge of the materials and methods used in the manufacturing and installation of carpet is essential. The following information will hopefully assist Designers, Suppliers, Installers, Owners, and others in becoming more aware of carpet floor covering issues and aid in choosing the appropriate carpet and installation methods to suit a project's requirements.

1 • CARPET FIBER

.01    Fiber Types:Carpet today is manufactured using a variety of fibre. There are two main fibre categories, natural and man-made or synthetic. Each type has advantages and              disadvantages and both can be used in a variety of carpet construction types either singularly or blended together in differing ratios, such as blended nylon / wool carpets.

• Natural Fibres: Many natural fibres have been used in the production of floor coverings long before recorded history.
  
  
  • Wool fibre: Wool is animal fibre or hair that is sheared from a variety of animals (sheep, goats, camels, alpacas, etc.). It is considered the traditional carpet fibre and its first known use dates back to 4000 BC in the valleys of the Tigris and Euphrates Rivers of Mesopotamia. The particular animal species, the breed within that species (e.g. Merino, Suffolk, Dorset, Texel sheep), the country / environment that it comes from, and the diet the animal is subject to results in long or short, fine or rough, and lustrous or stringy fibres. Because of these differences, different wools (usually from the same species) are typically blended together to achieve an acceptable quality level. As a result, the selection of wool fibre suitable for carpet pile is a task best left to someone knowledgeable in this field.
  • The following advantages and disadvantages are general comments only, and may vary slightly with the type and blend of wool used.
    
    Advantages Disadvantages Consumer acceptance Initial cost Appearance / styling Allergic to some Feel or hand Low stain resistance Resiliency Stain removal Cleanability Moderately static resistant Soil resistance / hiding Damaged by alkaline detergents Solvent resistance Must be treated for moths Flame resistance (burns slowly) Available in staple form only Versatility (very dyeable)   Abrasion resistance   For many years wool was the fibre used for most carpet pile and it is still viewed by some as the ideal carpet fibre. Indeed, except for those areas of extreme wear and abuse, wool, woven in a suitable construction will give excellent performance. Because of cost and other manufacturing considerations however, wool has now become a specialty fibre / carpet representing a fraction of both commercial and residential markets.
    
    In addition to wool, there are a variety of other "natural" fibre materials that are used to a limited degree in carpet construction.
    
    
    • Flax fibre: The first fibre to be used by man was derived from the bast or stem or stock fibres of the flax plant. Flax fibres are very strong, smooth, and easily dyed and were (and still are) woven into linen. The use of flax along the Nile River for a linen-like fabric dates back to 5000 BC and the remains of flax fabrics have been found in Switzerland dating back to the Stone Age. Linen is no longer used as a floor covering as it wrinkles easily and is not resilient enough. Flax is occasionally used in loop pile and flat weave rugs and carpets.
      
      
    • Cotton fibre: Cotton was developed in both India and Peru around 3000 BC and remnants of cotton fabric have been found in Egypt up to 2500 BC. Derived from the cotton plant, a member of the Hibiscus family, this leafy green shrub produces cream and pink flowers that turn into the fruit or cotton bolls. Before it is processed, the cotton fibre is called lint. The lint grows inside the cotton bolls, which are the fruit of the plant. Inside each boll there are around 30 seeds. When the cotton bolls open, one can see the fluffy white cotton fibre that has been growing inside. After the cotton bolls have been picked, they need to be cleaned and the seeds removed. The cotton fibre is then made into yarn or fabric. In carpet, its use is primarily for warp yarns in woven carpet. Today, it is seldom used as a face fibre other than in rugs.
      
      
    • Silk fibre: Discovered by the Empress Shi-Ling of China in 2640 BC who noticed that the cocoon of the silk worm (derived from a semi-liquid, continuous filament spun by the caterpillar that hardens on contact with air) came apart in filaments in hot water. Thereafter the care and feeding of silk worms became an established industry. The smooth surface of the silk fibre reflects light, and this reflected light is seen as lustre. Silk is processed and sold in many forms. There are two main types of silk depending on which species of caterpillar spins it. The Bombyx Mori extrudes a pure white silk that is very fine and highly lustrous and is sometimes commonly known as Mulberry silk. The Chinese Tussah silk worm spins a honey coloured fibre which is slightly coarser and less lustrous, but also less expensive. Because of the source, carpets and rugs made from silk fibre are very expensive.
      
      
    • Sisal fibre: derived from the large fleshy leaves of the sisal hemp grass or aloe plant (Agave or Americana Sisalanus). The name is derived from Sisal a Yucatan port town in Mexico where it's use was first discovered. Initially strands of sisal fibre were combined, twisted, and woven together to form both the front and back of sisal carpet (i.e., it is reversible in this form). Sisal carpet is very durable but is stiff, coarse, difficult to seam, and very difficult to clean. Because of its coarse open weave, sisal carpet is now coated on the "back" side for stability. Sisal is used as a backing material in carpet and can also be used to make rope.
      
      
    • Hemp fibre: derived from the bast or stem or stock fibres of various varieties of the hemp plant. This fibre is used primarily as a backing material in carpet but can also be used to make clothing and rope as well.
      
      
    • Jute fibre: derived from the bast or stem or stock fibres of various varieties of the jute plant that is native to India and Asia. Jute fibre can be made into twines and rough cordage and used for backing in woven carpet or woven into sheets and used as a secondary backing in tufted carpet. In many applications however, jute is being replaced by fibreglass, polypropylene, or other synthetic fibres. It is till used in knotted rugs but its single largest use is in sacks and bags, those of finer quality being called burlap or Hessian. The fibre itself can also be woven or hooked into rugs and mats.
      
      
    • Grass fibre: A fibre (primarily from the stems) of a variety of grass plants has been used to produce grass type carpets. These include sea and mountain grasses as well as bamboo (which is usually used to produce a hardwood flooring), and are limited in number.
      
      
    • Rayon fibre: A manufactured fibre composed of regenerated cellulose that usually comes from specially processed wood pulp. Because rayon is wood based, some consider it a natural product, although others consider it a synthetic product because of the chemical process used in its production. In the production of rayon, purified cellulose is chemically converted into a soluble compound. A solution of this compound is passed through spinnerets to form soft filaments that are then converted or "regenerated" into almost pure cellulose. Because of the re-conversion of the soluble compound to cellulose, rayon is referred to as a regenerated cellulose fibre. The rayon is produced as staple, i.e., in discreet lengths of fibre in which the group of filaments (termed "tow") are passed through a rotary cutter to provide a fibre, which can be processed in much the same way as cotton. Rayon fibre is soft and comfortable, highly absorbent, and easy to dye, and is usually blended with more durable fibres in carpet as rayon alone is not durable enough on its own.
      
      
  • Synthetic Fibres: The discovery of man-made or synthesized fibres from chemical compounds began in 1869 with the development of acetate followed by rayon developed from regenerated natural substances shortly after. Nylon was discovered by E.I. Dupont De Nemours in 1929 and was introduced in the form of a strong elastic fibre in 1935. Acrylic fibre appeared in 1947 and was followed rapidly by Polyester, Triacetate, Modacrylic, Polypropylene, and Spandex fibres. The discovery and evolution of these synthetic fibre materials became known as the "1st Generation" and the development of these fibres for use in carpeting is known as the "2nd Generation" or stage. During this phase for example, acrylic fibre was modified into modacrylic fibre with enhanced resistance to flammability, and acetate fibre was modified into triacetate fibre with better strength and resiliency. Many forms of nylon emerged during this phase, one better than or different from the previously developed fibre.
    
    
  • Further development in synthetic fibre production was directed at improving the "2nd Generation" fibres. These improvements involved blending, changing the molecular structure for a more lustrous appearance, and changing fibre shapes for better soil hiding quality and/or for greater colour or light absorption or deflection, and resulted in 3rd, 4th, 5th and now 6th generation fibres. New "environmentally friendly" fibres are also being developed from natural fibre sources such as corn stalks, etc.
    
    
    • Synthetic fibres have a number of advantages over natural fibres:
    • Unlimited supply of synthetic fibre versus possible shortage of natural fibre.
    • Cost control easier for synthetic fibre versus instability of cost of natural fibre due to elements of nature, disease, etc.
    • Better quality control and consistency of synthetic fibre production, which is not dependent on geographic or climatic conditions.
  
  
  • Synthetic fibres used in carpets today: Approximately 95% of carpets today are fabricated using synthetic fibres. The two principal ones are nylon (polyamides) and olefin (polypropylene). There are others:
    
    
    • Nylon fibre:The term nylon refers to a family of polymers called linear polyamides. Presently there are two common methods of making nylon for carpet fibre which results in the formation of Type 6 nylon, a polycaprolactam, and Type 6/6 nylon, a poly hexamethyleneadipamide. In both cases the polyamide is melt spun and drawn after cooling to give the desired properties for each intended use. Nylon fibre is available in both continuous filament fibre and staple fibre form, which can be heat set. It comes in a number of dye variants, so that it can be used in almost any carpet style or in any method of carpet construction. Today, nylon is by far the dominant fibre in tufted carpet pile yarn and it is used in approximately 2/3rds of synthetic carpet produced.
    •  The following advantages and disadvantages are general comments only, and may vary slightly with the type of nylon fibre used.
      
        Advantages Disadvantages Good bulk and cover High static (some grades) Excellent resiliency Stained by oil and grease (except for solution dyed and stain treated    nylons) Crush resistance Degrades and fades in sunlight Wearability / abrasion resistance   Clear colours with good lustre range   Soil resistance / hiding   Solvent  resistance   Static resistance (with static control)   Mildew resistance   Good cleanability   Dyeable  
      • Olefin fibre: Olefin (polypropylene and polyethylene) fibres are the products of the polymerization of propylene and ethylene gases carried out under controlled conditions with special catalysts. Olefin fibres are characterized by their resistance to moisture and chemicals and of the two types; polypropylene is the more favoured for general textile applications. Because the fibres resist dyeing, coloured olefin fibre is produced by adding dye directly to the polymer prior to or during melt spinning (i.e., it is pigment coloured). Olefin fibre has generally better light fastness and resistance to chemical discoloration than nylon but should not be used in areas where petroleum-based products are in high concentration. Olefin fibre is also generally less expensive (more economical) than nylon because it is melt spun and simpler to produce and is derived from readily available petroleum. Olefin is best suited for loop pile constructions or high, very dense heat-set cut piles and it is often used in both indoor and outdoor installations because of its resistance to moisture and mildew. It is used in synthetic turf for sports surfaces, and in the home for patios and game rooms. Many synthetic Berber carpets are made using olefin fibre.
        
        
      • The following advantages and disadvantages are general comments only, and may vary slightly with the type of olefin fibre used.
        
        Advantages Disadvantages Good bulk and cover Low melting point and resilience (shows "burn" marks from abrasion and wear) Good abrasion resistance Solvent resistance Stain resistance Fair colour clarity Moisture and mildew resistance Limited colour range in solution dye Solution dyeable Susceptible to staining by oil / grease based products Static free   Chemically inert   Lower cost  
        • Polyester fibre: The most common polyester for carpet fibre purposes is polyethylene terephthalate, or simply PET which is made by reacting ethylene glycol with either terephthalic acid or its methyl ester in the presence of an antimony catalyst. The reaction is carried out at high temperature and vacuum to achieve the high molecular weights needed to form useful fibre. This is also the polymer used for many soft drink bottles and it is becoming increasingly common to recycle them after use by re-melting the PET and extruding it as fibre. Polyester fibre is generally in staple form only and has the unique ability to take on dyes with luxurious colours. In its natural state soil resistance is less than satisfactory, but the fibre can be treated in such a way as to overcome this. It is less static prone than other man-made fibres and is better suited for low traffic areas. Polyester is also noted for its luxurious, soft "hand" and is used in thick, cut-pile textures.
          
          
        • The following advantages and disadvantages are general comments only, and may vary slightly with the type of polyester fibre used.
          
          Advantages Disadvantages Abrasion resistance Fair resilience Good colour and lustre Expensive to dye Low cost Degrades and fades in sunlight (sunlight weakens fibres) Piece dyeable Susceptible to oil-based stains Resistant to water-soluble stains   Moth and mildew resistant   Good cleanability   Non-allergenic   Bulk  
          • Acrylic fibre: Acrylic fibre is produced from acrylonitrile, a petrochemical that is usually combined with small amounts of other chemicals to improve the ability of the resulting fibre to absorb dyes and is produced by dry and wet spinning or extrusion. In the dry spinning method, material to be spun is dissolved in a solvent. After extrusion through the spinneret, the solvent is evaporated, producing continuous filaments which later may be cut into staple, if desired. In wet spinning, the spinning solution is extruded into a liquid coagulating bath to form filaments that are drawn, dried, and processed. Acrylic fibre is also unique among synthetic fibres because it has an uneven surface, even when extruded from a round-hole spinneret. Because of this the fibre has a high bulk to weight ratio and has the feel and look of wool. Acrylics have a tendency to fuzz somewhat (not pill) unless care has been taken in the manufacturing process to avoid this. Acrylic fibre has low moisture absorbency and dries relatively quickly, is resistant to the degrading effects of ultraviolet rays in sunlight and to a wide range of chemicals and fumes (making it suitable for outdoor use), but has relatively poor flame resistance compared with other fibres. Acrylic fibre is best suited for plush and cut and uncut pile carpets and is often used in bath and scatter rugs.
            
            
          • The following advantages and disadvantages are general comments only, and may vary slightly with the type of acrylic fibre used.
            
            Advantages Disadvantages Excellent bulk and cover Low abrasion resistance Good appearance retention Alkali resistance Low static level Poor flame resistance (except for modacrylics) Wide colour range   Solution dyeable   Moisture and mildew resistance   Good cleanability  
            • Fibre from recycled carpet: A fibre manufactured from recycled synthetic carpet fibre (a closed loop).
            
            
            • Fibre from recycled materials: A fibre or carpet manufactured from recycled materials such as plastic (e.g. PET or polyester carpet), from strips of cloth or rags as in a coil or braided rug, etc.
          .02    Synthetic Fibre Production: In the production of synthetic carpet fibre each batch of nylon, olefin, polyester, or acrylic chemicals in solid or crystal form must first be reduced          to a liquid molasses like state before it is then extruded under pressure through a spinneret (a device similar to a shower head). The size and configuration of the spinneret              holes determines the shape or profile of the fibre, and the number of holes determines the number of filaments in a yarn bundle (for continuous filaments). Depending on the              extrusion process, the extruded strands of fibre are then hardened and stretched while drying or after drying to reduce the fibre diameter even more. This stretching also                  causes the molecules in the fibre to arrange themselves in a more orderly fashion while at the same time strengthening and giving the fibre more ability to stretch without                  breaking. The spinning process of extrusion and hardening, not to be confused with yarn spinning, is accomplished by different spinning methods:
          
          
          • Wet Spinning: Fibres extruded through the spinneret are hardened by passing them through a chemical bath.
          
          
          • Dry Spinning: Fibres extruded through the spinneret are hardened by passing them through warm dry air.
            
            
          
          
          • Melt Spinning: Molten fibres extruded through the spinneret are hardened by passing them through cool air.
          
          .03    Fibre Shapes: The shape of a fibre contributes to its surface appearance and performance and will give lustre, bulk, and body to the fibre and yarn as well as determine the              hand or feel of a carpet. Different shapes and sizes of carpet fibre contribute to the characteristics of a yarn and the carpet in which it is used. The modification ratio of the                  cross sectional shape of a carpet fibre contributes to its soil hiding properties and performance. The shape of a natural fibre is determined by climate, diet, genetics, and                  breeding of the particular animal and can be altered to a degree by cross-breeding one animal with certain fibre properties with another having different properties in order to              achieve a more desirable fibre over a period of time. The size and shape of a synthetic fibre, on the other hand, is determined by the hole in the spinneret through which it is              extruded. In addition, a number of synthetic fibre shapes have been developed depending on the ingenuity of the fibre producer in order to provide better performance:
          • Round or Oval Fibre Filaments: a natural fibre shape as well as the shape of the 1st generation of nylon and polypropylene fibres produced. Although very durable in nature, clear round shaped synthetic fibres actually magnify the effects of abrasion and soiling.
          • Delta / Tri-lobial Fibre Filaments: synthetic fibres having a modified delta or tri-lobial cross section. Other similar shapes (dog-bone, dumb-bell, kidney shape) are included in this group. This shape was developed in order to diffuse the light and to help in hiding the effects of soiling and abrasion. Such shapes are also the 2nd generation of nylon and polypropylene fibres to be produced.
          • Square or Rectangular Fibre Filaments: synthetic square or rectangular shaped fibres with some having a number of continuous hollow voids that further help to diffuse the light and thus contribute to soil hiding. Such voids are no more than 10% of the filament in order to maintain its strength. This shape also results in fewer spaces between closely packed fibres. Such shapes are also the 6th generation of nylon fibres to be produced.
          
          
          
          
          
          
          
          
          
          
          
          
          
          • Note: The use of the term "generation" was commonly used to define the advances in the production of nylon fibres, although some other fibre types use this term in a similar fashion. Today, such terminology is waning or may no longer be in use. The following information is offered for historical purposes only:
            • 3rd generation of nylon fibre filaments: the addition of static control properties to reduce the static charge build-up common in nylon fibre.
            • 4th generation of nylon fibre filaments: the addition of fluorochemicals modifying the surface tension of nylon fibres to make them more resistant to soiling with the added benefit of resistance to water and oil based stains.
            • 5th generation of nylon fibre filaments: the addition of chemical treatment with acid dye resistors to block most common food and beverage stains.
            • 6th generation nylon fibre filaments: the development of square or rectangular hollow filament fibre. Note that there is no connection between Type "6" and "6/6" nylon fibres and the term "6th" generation.
          
          
          • Other synthetic fibre filaments: (polyester, olefin, acrylic, rayon, etc.) These fibres have shapes similar or identical to those noted above. In each case the fibre manufacturer should be consulted for specific information in regard to generation shapes and properties.
          
          .04    Fibre Filaments: After natural fibres are collected and cleaned and synthetic fibres are extruded and hardened, the single strands of fibre filaments are then processed into              three basic categories:
          • Mono-Filament: A single filament of fibre is stretched about four times its length for strength and elasticity and is then wound onto a spool for use primarily in the manufacturing of hosiery and fabrics
          • Multi-Filament: A number of continuous filaments are loosely gathered into one strand. For synthetic filaments this occurs after being extruded and then stretched about four times their length for strength and elasticity. The strand of filaments is then twisted together to hold all of them together with the size and number of filaments varying to suit the end requirements. This multi-filament is used in manufacturing heavier clothing, carpets, and other items.
            
            
          • Staple fibre: Hundreds of continuous multi-filament strands are brought together to form a loose rope. In the case of synthetic fibres the rope is stretched and crimped. This mechanical process gives the synthetic fibres softness, springiness, and bulk similar to that found in natural fibres. The (crimped) rope of filaments is then cut into short pieces from one to several inches long called staple. These "staple" fibres are then baled and shipped to spinning mills where they are then re-made or spun into yarns suitable for clothing, carpet and other items.
            
            
          • Note: Continuous synthetic fibre filaments without twist are called Tow, which is collected in a loose rope-like form and held together by crimp, before it is cut into staple fibres.
            
            For synthetic carpet yarns spun on the common, modified worsted systems, most staple is 150 mm (6") to 200 mm (8") long. Staple fibre may also be converted directly into non-woven fabrics, such as needle-punched carpet.
            
            For wool carpet, the fibres are separated into combing wool with a staple length of 65 to 180 mm (2 1/2" to 7").
          
          
          
          
          
          
          
          
          
          
          
          
          
          .05    Fibre Crimp: Fibre crimp refers to the waves or bends that occur along the length of a fibre and it may occur naturally or may be introduced. Crimp increases cohesiveness,              resiliency, resistance to abrasion, and gives increased bulk to a carpet. There are three kinds of crimp:
          • Natural Crimp: This occurs naturally in wool and cotton fibres
          • Mechanical Crimp: This is produced by passing the fibre between different shaped rollers and if the rollers are heated, the crimp becomes permanent.
          • Chemical Crimp: This is produced in the hardening process after the fibre leaves the spinneret.
                   For synthetic fibres crimping is a method of texturizing staple and continuous filament yarn to produce irregular alignment of fibres and increase bulk and covering power. This          also facilitates the interlocking of fibres, which is necessary for spinning staple fibres into yarn.
          
          .06    Fibre Properties: The production of fibre using various materials and process methods creates fibres with different physical properties and chemical compositions. Physical              properties include fibre length, diameter, surface contour, crimp, and cross sectional shape. Chemical properties are based on the molecular arrangement within the fibre.
          
                   The following fibre properties play an important role in a carpet's performance:
          • Durability: This is self-explanatory and refers to fibres that are long wearing.
          • Strength: A fibres' strength is usually related to tensile strength (pounds per inch) or tenacity (grams per denier).
          • Resiliency: The ability of a fibre to recover from applied "stress" such as stretching, bending, or twisting. The resiliency of a fibre determines the ability of a carpet to recover from crushing, which in the end will also determine the look of a carpet and its ease of maintenance.
          • Abrasion Resistance: The ability of a fibre to withstand rubbing or abrasion (wear) during everyday usage. Abrasion resistance varies with the type of fibre.
          • The following is a list of the abrasion resistance of the fibres alone in decreasing order of resistance:
            • Nylon
            • Olefin
            • Polyester
            • Acrylic
            • Wool
            • Cotton
            • Rayon
            • Acetate
            Note: The abrasion resistance of these fibres when used in a carpet is affected by the type and blend of fibres used, the fibre colour, as well as the carpet style, and construction, etc.
            Note: This list should not be used to determine the abrasion resistance of any carpet.
            
            
            • Elasticity or Memory: The ability of a fibre to return to its original shape after deformation.
            • Flexibility or Plyability: The ease of a fibre to take bending or shaping, which is particularly applicable in twisted yarns.
            • Stiffness or Rigidity: The opposite to flexibility. Carpet fibres must have a certain degree of stiffness in order to become a good component in twisted yarn.
            • Elongation: This is the elongation of a fibre due to stretching and has much to do with the crimp put into a carpet fibre. A good fibre should not have an elongation factor of more than 10%.
            • Stability: The ability of a fibre to retain its size, shape, and form when it is subjected to moisture, heat, or pressure. The stability of the fibre will determine the overall stability of the carpet.
            • Plasticity: The ability of a fibre to be shaped by moisture, heat, or pressure. This, like resiliency, will also determine the look and durability of a carpet and its ease of maintenance.
            • Density and Specific Gravity: These characteristics are measures of the weight of a fibre. Density is the weight in grams per cubic centimetre (g/cm3), and specific gravity is the ratio of the mass of a carpet to an equal amount of water at 4°C. The weight of a carpet is determined by the weight of the fibres in it.
            • Cohesiveness: The ability of a fibre to cling together during the spinning process which is important for staple fibres. Cohesiveness is better achieved by putting a crimp into the fibre, which is most applicable for staple filaments.
            • Absorbency: The ability of a fibre to take up moisture, expressed in terms of moisture re-gain. Absorbent fibres do not have much static build-up, which makes the resulting carpets more comfortable in dry cold weather. Absorbent fibres which take on moisture are somewhat easier to dye. Absorbency also relates to resiliency, meaning that a moist carpet will crush more than a dry one.
            • Wicking: Wicking is the conduction of moisture along a fibre (by capillary action) even though the fibre itself may or may not absorb moisture.
            • Electrical Conductivity: This is the ability of a fibre to store/ conduct static electricity resulting from friction or foot traffic across the carpet surface which causes production of an electrostatic charge. The discharge of electrostatic potential from the carpet through a person to a conductive ground, e.g., a doorknob. Various static control systems and finishes are used to dissipate static charge before it builds to the human sensitivity threshold.
            • Hand: This refers to the "feel" or tactile aesthetic qualities of carpet. Factors determining how carpet feels to the hand include pile weight, stiffness, lubricants, fibre type and denier, density, backing and latex. The words soft, lofty, lively, warm, wool-like, etc. are descriptive terms used to describe the hand or feel of a carpet and do not necessarily mean the same thing to all people.
            • Loft: This is a descriptive term referring to the ability of a fibre, yarn, or carpet to spring back to its original thickness after being compressed. In fibre, loft is due to crimp.
            • Cover: This is the ability of a fibre to occupy space for concealment or protection. Fibres with an irregular cross section and crimp, or curl, or twist, give better protection than others.
            • Body: This refers to the firmness or rigidity of a carpet and is usually obtained by the use of course fibres.
            • Lustre: This refers to the brightness or sheen of fibres, yarns, or carpet and is due to the light reflected from the fibres. Smooth flat fibres reflect more light than rough or round fibres. Yarns of long fibres which are laid together with little or no twist reflect more light than yarns with short fibres which have been twisted together. Synthetic fibres are produced in various lustre classifications including bright, semi-bright, semi-dull, and dull. Bright fibres usually are clear (have no white pigment), whereas duller fibres have small amounts of white pigments, such as titanium dioxide. Carpet lustre also depends upon yarn heat-setting methods, dyeing and finishing. In high-traffic areas a duller or low lustre carpet is often preferred for its soil-hiding ability.
            • Colour: This refers to the beauty, and many times the dyeability of a fibre. Absorbent fibres take up dye more readily than non-absorbent fibres.
            
            .07    Fibre Sizing and Weight: The production of carpet fibre using different materials and production methods results in yarns of different sizes and weights.
            
                     Yarns are bought and sold by the weight, not by length. Because of this yarn sizes (or numbers) are used to express a relationship between the unit length and weight of a              yarn, or more correctly, it's linear density. This relationship also reflects the diameter or thickness of the yarn, although not as precisely. Basically the relationship to size can be          expressed noting that a low weight yarn is finer (smaller) than a high weight yarn of the same length. This relationship becomes less precise due to variations in twist and
                     fibres. Yarn sizes express the relationship between weight and length in a yarn and a close, but not precise, relationship to diameter. There are two numbering systems used              that relate weight length and size of the yarn.
            • Direct Numbering System: This system is used for filament yarns. In this system as the numerical value of the size goes up, so does the weight per length and the diameter increase correspondingly. Direct numbering is expressed in terms of weight in grams over length in meters. The most common direct numbering terms are:
              
              
              • Denier: the weight in grams of 9000 metres of filament (equal to Tex x 9). If 9000 metres of yarn weighs 1300 grams the denier rating is 1300.
              • Tex: the weight in grams of 1000 metres of filament.
              • Decitex: the weight in grams of 10,000 metres of filament.
            
            
            • Using this numbering system, a yarn number may be described by using the total denier and the number of filaments in a bundle. For example the number 150/48 means that the weight divided by 9000 meters is 150 and there are 48 filaments in the bundle.
              
              The tex of the individual filaments in synthetic filament yarn or staple fibre is determined at extrusion and this affects the performance of the final carpet. The lower the single fibre tex, the softer the hand of the carpet. The higher the single fibre tex value, the better the resistance to soiling, crushing, and abrasion. Common sizes for commercial carpet use generally range from 16 to 40 dtex. Wool fibres naturally contain a range of fibre sizes and wool for carpets is carefully chosen from breeds of sheep having the best mix of sizes and other properties for carpet use.
              
              While some filament yarns are used in carpet without plying (e.g. in some multi or level loop pile carpets) in the majority of cases they are plied. A 3-ply yarn from 1450 dtex yarn would be written 3/4350 dtex and would have a resultant linear density of 4350 dtex. Denier is similarly designated. A 3-ply spun yarn from 3.0 cc yarn would normally be written 3.0/3 cc and would have a resultant linear density of 1.0 cc.
              
              
              • Indirect Numbering System: This system is used for spun yarns. In this system as the numerical value of the size goes up, the weight per length and the diameter decreases correspondingly. The most common indirect numbering terms are:
                
                
              • Cotton Count (cc): A yarn numbering system based on the length and weight originally used for cotton yarns and now employed for most staple yarns. It is based on a unit of length of 840 yards (256 m), and the count of yarn is equal to the number of 840 yard long skeins required to weigh one pound which is referred to as a "hank" (This is also equal to 590.6 / tex). Cotton count is an inverse scale whereas tex and denier are direct scales. So under this system, the higher the number, the finer the yarn. So one cotton count (1 cc) = 840 yards of cotton, the coarsest cotton yarn. A 3 cc yarn would be one third as coarse and would be expressed as 3/1 cc. A typical carpet yarn might be a three cotton count two plied yarn, that is written as 3.0/2c.c. Refer also to "hank" and "worsted count."
              
              
              • Worsted Count (wc): A yarn numbering system that expresses the number of hanks required to make a pound of yarn. A hank of worsted wool is equal to 560 yards. One wc equals 560 yards of cotton, the coarsest worsted yarn. Worsted sizes are the reverse of cotton sizes. A two-ply number 6 worsted yarn would be expressed as 2/6 wc and would yield 1680 yards per pound. A worsted count (wc) can be converted to a cotton count (cc) by multiplying the cc by 1.5, or wc = cc x 1.5. Refer also to "hank" and "cotton count."
            • Woolen Count: There are two systems of woollen yarn measurement used:
              
              
              • Woolen Cut: based on one hank measuring 300 yards in one pound of yarn.
              • Woolen Run: based on one hank measuring 1,600 yards in one pound of yarn. A two-run yarn has 3,200 yards.
            
            .08    Fibre Manufacturers: Both natural and synthetic fibres are produced by a variety of material manufacturers and carpet mills. Synthetic fibres can be classified by their              source manufacturer which may in some instances give an "assured quality" level of materials:
            
                     The following fibre properties play an important role in a carpet's performance:
            
            
            • Raw Synthetic Material: Material (e.g. Type 6 and 6/6 nylon) manufactured in pellet, chip, or flake form by a "material manufacturer." This raw material may then be melted and extruded into fibre by the material manufacturer or supplied to a carpet mill that will use the material to extrude their own fibre with their own modifications to the mix before extruding.
            
            
            • Mill Extruded Fibre: Fibre manufactured from raw synthetic material purchased from one or more material manufacturers by a carpet mill or by plants owned by a carpet mill. Such fibre may be "unbranded" or "private labelled" by the carpet mill.
            
            
            • Trademark / Branded Fibre: "Proprietary" fibre in staple or BCF form that is manufactured by a material manufacturer (chemical source) that is committed to fibre production. This fibre is purchased by a carpet manufacturer (mill) and fabricated into carpet. If the carpet using this fibre meets the strict performance and construction criteria established by the material manufacturer, the carpet manufacturer will be permitted to use the proprietary fibre's trademark or brand name complete with its fibre / performance warranties if so certified by the fibre manufacturer. This "certified fibre use" is governed by a licensing agreement between the material manufacturer and the carpet mill. The carpet must be tested in accordance with recognized testing procedures and must meet or exceed the benchmark test levels established by the material manufacturer.
            
            
            • Unbranded Fibre: Fibre that is either produced by a material manufacturer who will not permit the carpet mill to use the fibre "brand" or "trademark" name, or is produced usually by intermittent batch process and using materials from a variety of sources by a carpet mill or by plants owned by a carpet mill. In either case the carpet mill will add their own private label and offer their own carpet performance warranties if the carpet meets the performance and construction criteria that they themselves have established.
            
            
            • Private Label Fibre: Fibre that is manufactured by a carpet mill using known or unknown materials or is fibre purchased from a variety of known or unknown sources. The carpet mill may provide their own warranty, but as above, the fibre does not carry a material manufacturer's certified or "branded" fibre / performance warranty.
            
            
            • The use of "cocktail" blended fibre mixes in both unbranded and private labelled fibre, may at times result in carpet with unknown, differing, or inconsistent performance levels.
            • It is important to determine the type of fibres by source manufacturer (i.e., branded, unbranded, or private label fibre) when selecting and/or specifying any carpet in order to establish a level playing field in regard to fibre material used.
            
            .09    Fibre Identification: This applies to examining carpet samples as well as installed carpet to determine the type of fibre.
            • Look and Feel: As synthetic fibre can be made into carpet that looks and feels like a natural fibre carpet and natural carpet fibre can be changed by certain finishes, it is not always easy to discern one from another, and only experience and careful analysis will tell the difference. A number of simple points may be used to discern what type of fibre it present:
              
              
              • Length of fibre (untwist a yarn for this). Any fibre can be made into a staple length but not all can be filament length.
              • Lustre or lack of lustre. Refer to 3.07.20 for details.
              • Body, texture, and soft-to-hand, rough-to-smooth, warm-to-cold, or stiff-to-flexible feeling. Refer to 3.07 for fibre properties.
            • The following tests are simple "field tests" and should not be relied on as a definitive test to discern the type of carpet fibre. In all cases only "laboratory" testing will ensure exact and def initive results.
              • Burn Test: Fibres types may be identified by conducting a burn test with a visual inspection and smell on a sample of fibres with the following observable results:
              
              
              • Nylon, polyester and mod-acrylic fibres:
                • Self-extinguishing - melt and burn only while in flame or shortly thereafter.
                • Nylon fibre produces hard tan beads and celery-like odour.
                • Polyester fibre produces hard tan beads and an aromatic odour. - Modacrylic fibre produces hard black beads.
              
              
              • Olefin and polypropylene fibres:
                • Not self-extinguishing.
                • Form wax-like beads.
                • Olefin produces a wax-like odour.
              
              
              • Acrylic and acetate fibres:
                • Not self-extinguishing - melt and burn.
                • Form hard black plastic beads.
                • Acrylic produces a chemical odour.
                • Acetate produces an acetic odour.
              
              
              • Rayon and viscose fibres:
                • Not self-extinguishing
                • burn and char.
                • Form soft grey ash with smooth edge and afterglow.
                • Fibres produce an odour of burning paper.
              • Wool, silk and other protein fibres:
                • Self-extinguishing - burn briefly and char producing a burning hair odour and a crushable black ash residue.
              Note: When performing a burn test, do not hold fibre tufts in your fingers. Use a non-flammable holder, tweezers, etc. In addition, use a lighter rather than a match, as the odour from the match will mask the odour given off from the burning fibres.
              
              
              • Chlorine Bleach Test: A test using chlorine bleach slightly heated or at room temperature may be used (following normal precautions for using bleach) to identify fibre types. Bleach will dissolve wool and silk fibres and it will remove the colour from "standard-dyed" nylon while the colour of solution dyed nylon and the colour of olefin fibres will be unaffected.
              
              
              • Acid Test: A test using formic acid can be conducted to determine if the carpet fibre is nylon. A tuft of fibre is placed in a vial or test tube containing formic acid. If the fibre is nylon it should completely dissolve within minutes.
              
              
              • Water Floatation Test: A test using plain water can be conducted to distinguish olefin (polypropylene and polyethylene) fibre from others. These fibres with a specific gravity of less than 1.0 will float on water while all others will sink as they have a specific gravity greater than 1.0. Tufts used for this test must be without any backing attached and must be repeatedly and carefully squeezed to release any air entrapped around the fibres. If the fibres slowly float to the surface they are olefin while those that sink may be nylon, polyester, or acrylic fibres.
              
              
              • Distinguishing Carpet Fibre Generation: To identify the "generation" of nylon fibres and coatings used on other fibre types the following procedures may be conducted:
              
              
              • Advanced generation nylon fibres with a fluorochemical coating that will repel both water based and oily substances. This can be confirmed by applying a few drops of water and oil on the face of the carpet and observing the results. If the substance beads, fluorochemicals are present and effective.
              
              
              • To confirm the presence of acid dye resisters, submerge a few tufts taken from the edge of the carpet in an artificial red coloured beverage such as Kool-Aid, wait five minutes, flush with water and a mild detergent and compare. If stain blockers are present and effective, no discolouration will be visible.
            
            .10    Carpet Yarn Production: Carpet is fabricated by either spinning short lengths of natural fibres together to produce continuous strands of yarn or by extruding synthetic fibre to          produce single or multi-filaments that are then combined to form continuous strands of yarn.
            
            
                     In regard to wool, once collected, the wool fibres must be carefully scoured, blended, carded, and spun to produce continuous blended strands of yarn. The exact process of              spinning selected depends on both the fibre properties and the desired characteristics of the finished yarn in terms of bulk and twist levels. The methods for handling and                  spinning wool are different from those used for synthetic fibres and are not readily interchangeable. Once spun, the skeins of yarn produced may be used in a natural (undyed)          state or are dyed to provide colours required.
            
                     Most man-made fibres are available from suppliers either in continuous filament form or as staple fibre, the latter being a state similar to naturally occurring fibres such as wool          and cotton. In continuous filament yarns the individual elements are extruded as continuous strands, which are then texturized or bulked. A number of these bulked continuous          filaments (BCF) are collected to form a yarn by the fibre producer. This yarn is then ready for either further processing or for direct tufting by the carpet mill. A property of this              yarn is that it produces a carpet that is not susceptible to "shedding."
            
                     To produce staple fibres, continuous filaments are texturized or crimped, collected, and cut into short lengths ranging from 100 to 230 mm (4" to 9"). They must then be 'spun'          into yarns using processes, similar in nature to those employed for cotton or wool that involve fibre blending, carding, drawing, and twisting. The twist level is important and will          vary according to the final carpet style to be produced. Fibres of different colours or dye affinities may be combined at the blending or drawing stage to produce yarns having a          heathered look in the finished carpet. Furthermore, different fibres may also be blended together to produce unique appearance and performance characteristics.
            
                     Both filament and spun yarn may be subjected to additional processing prior to tufting. This may include plying of two or more yarns together (2 ply, 3 ply etc.) in which case              both the degree and direction of twist will influence the properties of the resultant carpet. Following plying, the yarns may be heat-set if they are intended for use in cut-pile                  carpets. This setting process enables the cut pile yarns in a carpet to maintain their twist, which is particularly important for Saxony or Frieze constructions. These will now be          examined in further detail.
            
                     As noted above, before a yarn is manufactured into carpet, a number of different processes are used to provide suitable yarns:
            
            
            • Blending: This is an essential process that thoroughly blends the "raw" and dissimilar staple fibre into a homogenous mixture. Once blended the fibres may be either baled again for transport on to the next stage or they may be conveyed directly into the carding process.
              
              
            • Air-Entanglement: Also referred to air-interlacing, intermingling, commingling, or heathering, this is a process in which BCF fibres are "locked" together by air jets at regular or irregular intervals. The resulting yarn is characterized by a heather appearance. Using solution and yarn dyed yarns with different dye affinities and various air-entangling processes makes it possible to produce a wide range of aesthetics in finished yarns that range from highly blended, near solid looks to yarns where individual colours are accented and colour separation mimics that of plied yarns.
            
            
            • Carding: This next stage passes the blended / homogenous staple fibres through a series of rolls that are covered with many projecting wire teeth. This process cleans, opens, and aligns the fibres in a parallel configuration and forms them into a continuous, untwisted string called sliver. This results in uniform, constant density slivers for delivery to yarn spinning frames. Carding helps remove impurities and unusable (short) fibres from natural fibre stock (cotton, wool).
            
            
            • Pin Drafting: This next stage takes the carded sliver and converts it into continuous lengths which look like thick coils of soft rope. This drafting process may be repeated several times to achieve greater consistency in the fibre mix.
            
            
            • Spinning: From the pin drafter the rope of fibres is segregated into thinner sliver, given twist depending on what quality of yarn is desired and then wound onto bobbins.
            
            
            • Twisting: In this process a single strand of yarn may be combined with another strand or a number of strands to form a yarn of several plies. Most yarns used in carpet are twisted together at varying degrees in both the singles and plied states depending on the purpose of the intended yarn. Twist may be inserted in either an in or out direction as designated by 'S' twist and 'Z' twist. The direction of twist is explained as follows. A yarn or cord has S twist if, when held in a vertical position, the spirals conform in direction of slope to the central portion of the letter 'S', i.e. spiralling down to the right and 'Z' twist if the spirals conform in direction of slope to the central portion of the letter 'Z', i.e. spiralling down to the left. The amount of twist is indicated in turns per meter (t/m) or turns per inch (tpi).
            • The twist level of the yarn affects a carpet's appearance, durability, and resistance to matting.
              
              Refer to the following diagram in regard to loose or tight twist details.
              
              
              • Heat Setting: In this process the twisted yarn is thermally stabilized to a final crimp or twist configuration so as to reduce loss of twist and bulk in service. This is important in cut pile carpet. Most nylon, olefin, and polyester cut pile carpets are heat-set.
                
                
              • This heat setting process may be accomplished by using one of three different processes utilizing steam or dry heat.
                
                
                • Autoclave process: The skeins of yarn are first tumbled in steam to relax the fibres and then transferred in batches into an autoclave where the yarn is set using superheated steam under pressure, usually at temperatures in the 115° to 150° C (240° to 300° F) range (often 132° C (270° F) for nylon).
                • Because of the increased demand for heat set yarns two continuous heat setting methods using steam and dry heat were developed which resulted in a more uniform yarn at lower costs than those produced by the autoclave batch method. These methods are:
                  
                  
                  • Superba process: A continuous "autoclave" method utilizing a pressurized steam pre-heat expansion chamber to bulk loosely coiled / twisted yarn and a pressurized heat expansion chamber to heat lock the yarn.
                  
                  
                  • Suessen process: A continuous method utilizing a dry heat expansion chamber to heat set twisted yarn that has been wrapped around coils.
                
                .11    Yarn Types: The above noted processes results in the formation of various yarn types:
                
                
                • Continuous Filament Yarn: Yarn formed into a continuous strand from one or more continuous filaments.
                
                
                • Bulked Continuous Filament (BCF) Yarn: Continuous strands of synthetic fibre formed into yarn bundles of a given number of filaments. The yarn bundles are crimped or texturized, a process that changes the straight filaments into kinked or curled ones, to increase bulk and cover.
                
                
                • Spun Yarn: Yarn formed from staple by spinning or twisting into a continuous strand.
                
                
                • BCF or Staple Yarn: When it comes to durability, there is little difference between bulked continuous filament (BCF) and staple (spun) fibres. The difference lies in the length of the fibres in the yarn, with staple having shorter lengths, giving the yarn more bulk (sometimes described as being more like wool). When carpet is manufactured with staple fibre, there will be initial shedding of shorter fibres. It will soon stop, depending on the amount of foot traffic and frequency of vacuuming. Wool is a naturally staple fibre; nylon and polyester can be staple or continuous filament; and olefin (polypropylene) is usually BCF.
                
                .12    Filament / Yarn / Carpet Colour:
                
                
                • Refer to Part C04B - Material Guide - Selection for colour selection parameters.
                
                
                • Colouring or dyeing of carpet fibre, yarn, or the manufactured carpet itself is accomplished by the addition or incorporation of small amounts (usually one percent or less) of highly coloured materials known as dyes and pigments. These materials are capable of permanent physical or chemical attachment to the carpet fibres in small quantities. Most dyes are applied from water solutions or dispersions.
                
                
                • Pigments are highly coloured, insoluble, powered substances used to impart colour to other materials. White pigments, e.g., titanium dioxide, are dispersed in fibre-forming polymers to produce delustred (semi-dull and dull) fibres.
                
                
                • To be dyeable the synthetic carpet fibre materials or the natural or synthetic carpet fibres must be receptive to the dyes and pigments to be used.
                • There are two basic dyeing methods used: Prior to, during, or after fibre or yarn production (pre-dyeing) or after carpet fabrication (post-dyeing)
                  
                  
                  • Pre-dyeing methods: These methods may be before synthetic fibre extrusion or after synthetic or natural yarn production. Carpet that uses such yarns is defined as pre-dyed carpet.
                  
                  
                  • Solution dyeing: In this pre fibre extrusion method the dye is added to the synthetic fibre mix (i.e., the molten chemical polymer solution) before it is extruded. The extruded filament is thus impregnated with the pigment and results in evenly toned fibre with a high degree of colour-fastness. The solution dyed fibres are sometimes referred to as being dope dyed or spun dyed.
                  
                  
                  • Bulk dyeing: This is a general term referring to dyeing materials in bulk such as fibre prior to being spun into yarn form, and yarn before or after being plied.
                  
                  
                  • Stock dyeing (for staple fibre only): In this method undyed, loose staple fibres are dyed in a vat before they are blended, carded, and spun into yarn. The purpose of stock dyeing is to ensure even colour tones throughout the entire batch of staple fibres.
                  
                  
                  • Skein dyeing: This dye method is applicable to undyed spun yarns, bulked, continuous filament yarns, heat set yarns, and non-heat set yarns of many fibre types. The yarn must have sufficient strength and scuff resistance to withstand skein winding and back winding onto cones. The yarn is plied and heat set (where applicable), reeled into skein form, and then dyed in skein dye kettles. The heat of the liquid dye sets the colour to ensure a uniform colour throughout the skein. This method only yields small to mid-sized dye lot batches and is especially suited to the production of custom colourations and is economically attractive if combined with autoclave heat setting. A modified skein dyeing process (the hussong multicolour process) dyes various portions of the skein different colours, resulting in a yarn with various coloured segments along its length. The rather long colour bands are less random than those achieved by other space dyeing methods, but are used to advantage in multicolour cut loop styles. Solid colour skein dyed yarns are primarily used in woven carpet and for accent colours in tufted graphic styles.
                  
                  
                  • Differential dyeing: This is a method used to create different colours within a strand of yarn in one dye operation by combining filaments (usually of the same generic type (e.g. nylon) that have different dye affinities (i.e., the filament fibres have been modified chemically to make them receptive to acid or basic (cationic) dyes. Such fibres are also available in different dyeable levels (light, medium, and deep) and can be used in combination resulting in fibres accepting dye deeply, lightly, or not at all. This dyeing method produces multi-coloured yarn with interesting random effects or graphic patterns as in piece dyeing.
                  • In addition, using deep dye fibres (i.e. modified synthetic fibres with increased dye affinity relative to regular dye fibres) in combination with regular dye fibres, a two-colour or two-tone effect can be achieved within one dye bath.
                    
                    
                    • Space dyeing: This is a method whereby two or more different colours are "printed" along the length of yarn strands before they are used. There are three basic processes used to create this effect:
                    
                    
                    • Warp system process: multiple strands of yarn are continuously printed at spaced intervals with different colours. These yarns usually have "long" spaces of each colour.
                    
                    
                    • Knit-de-knit process: yarn is first knitted into a tubular fabric (sock), then is dyed to a solid colour and then overprinted with up to seven different colours. These yarns usually have "short" spaces of colour.
                    
                    
                    • Continuous dye process: yarn is dyed as singles or plied yarn and colour is applied either by air jet or dye rolls. This process allows for yarns to have either long or short spaces of colour.
                  
                  
                  • Package dyeing: This is similar to skein dyeing inasmuch as finished but undyed yarn is wound on perforated tubes or wire forms and the packages of yarn are dyed by passing dye liquor through the perforations or wires under pressure to soak the yarn. After dyeing the packaged yarn is ready for tufting or weaving.
                  
                  
                  • Pad dyeing: This is a continuous process of dyeing fibre stock or yarn (as well as finished carpet). The material to be dyed passes through a trough containing the dye liquor and then between heavy rollers which squeeze the dye liquor evenly into the material.
                  
                  
                  • Continuous solid colour dyeing: A process of dyeing singles or plied yarn using dye rolls. The application of dye is similar to the continuous space dye process except that a single colour is applied to the yarn. These solid colour yarns can be tufted into multicoloured carpets.
                
                
                • Post dyeing methods: There are a variety of methods used in dyeing carpet after it is manufactured (i.e. the carpet is dyed in its tufted form). Such carpet is defined as post-dyed as opposed to being pre-dyed (using pre-dyed yarn).
                  
                  
                  • Beck (piece) dyeing: In this method a piece of greige carpet is sewn into a loop and hung on a large reel in a large vat (dye beck unit) and then is continuously rotated and immersed in a heated dye liquor for a set period of time under controlled conditions. Most commonly used for cut pile carpet, it offers good custom colour flexibility and excellent colour uniformity throughout the carpet. The amount of carpet dyed is limited by the size of the loop or roll.
                  
                  
                  • Continuous (piece) dyeing: In this method greige (undyed) carpet or yarn is dyed in a continuous production line through a dye (rather than in batch lots where carpet or yarn is submerged in a beck). The process is frequently referred to by the name of one of the prime machinery manufacturers, Eduard Kuster (pronounced "Kooster") as Kuster dyeing. Continuous dyeing can produce multicoloured or solid-coloured carpet. Multicoloured carpet is achieved by using cross-dyeable yarns or with various accessories that can give a pattern or overprint. Advantages include large dye lots, relatively low cost and colour flexibility. However, this method is more critical than beck dyeing or yarn dyeing for side-to-side matching consistency (the carpet must be installed in roll sequence).
                    
                    
                  • Another continuous piece dyeing method used is to flow the dye over the carpet. The carpet is then heat set, rinsed, and dried.
                    
                    
                    • Tak or Random dyeing: This is a continuous dyeing method used on greige (undyed) carpet or caret dyed in a single base colour to obtain multi-coloured dye effects. Coloured dye liquor is applied in a controlled pattern of droplets producing random, multicolour patterns, which are usually less sharply defined than printed patterns. Using several Tak machines in tandem, a number of different colours can be applied at pre-set intervals.
                    
                    
                    • Gum Tak dyeing: This is a continuous dyeing method similar to Tak dyeing for producing coloured patterns. A dye resistant gum-like chemical is applied to the carpet pile which allows only part of the yarn to be dyed. The gum is later washed away so that it doesn't become part of the carpet. There are a number of advantages of Tak dyeing:
                    
                    
                    • Tak dyeing can produce the same colour effects as tufted carpet that uses different coloured fibres.
                    • Compared to printing dyeing, Tak dyeing is faster (up to three times the speed of printing).
                    • Tak dyeing can simulate space dyeing effects at far less cost.
                  
                  
                  • Resist dyeing: This is a continuous dyeing method similar to Gum Tak dyeing for producing coloured patterns except that greige (undyed) carpet is first printed with colourless chemicals that alter the dye affinity of the printed areas. The printed areas in nylon carpet, for example, may be altered to be light dyeing and/or cationic dyeable relative to the untreated, regular, acid dyeable nylon. Subsequent piece dyeing in a dye beck with appropriately selected dyestuffs produces a coloured pattern. In this fashion, numerous colour ways may be produced from a single print run.
                
                
                • Carpet dye lot size: Maximum dye lot sizes vary with the dyeing method used which may be a concern where large quantities of a particular carpet colour are required. The design Consultant or Owner should verify colour production limitations with the carpet manufacturer.
                
                
                • Carpet printing methods: There are a variety of methods used in dye printing carpet after it is manufactured using equipment similar to a printing press for printing flat textiles and paper. Colours and patterns may be flat or rotary printed. These include the following:
                  
                  
                  • Flatbed screen printing: In this method tufted greige (undyed) carpet complete with secondary backing is fed into a flat printing machine. As the carpet is fed through, a metal screen with a perforated pattern is lowered onto the carpet and dye is forced through the perforations by a squeegee. The carpet stops as each new screen (one for each colour with the lightest colour usually added first) is lowered to add another colour and pattern over the first. In the Zimmer printing process, magnets on the underside of the carpet are used to draw the dye deeper into the face of the carpet. This method of printing is popular but relatively slow in comparison with newer printing and dyeing techniques used.
                  
                  
                  • Rotary screen printing: Most popular method, similar to the above but instead of being applied by flat screens with the carpet stopping periodically, the rotary printing uses a series of rolling cylinders with raised embossed patterns coated with dye. Rollers rotate in the same direction as the carpet, making a continuous process with each colour and pattern having a separate cylinder or roller. As many as 16 cylinders may be used in this process to produce a multi-coloured and patterned carpet.
                  
                  
                  • Stalwart printing: This method employs sponge rubber pattern elements on wooden rollers and is similar to the other printing processes noted above.
                  
                  
                  • Jet printing / injection dyeing: In this method the finished carpet is dyed using computer controlled individual needle-nozzles that inject dye in selected precise patterns as the carpet is fed through. Separate jets are used for each colour. Solid colour broadloom to extremely complicated patterns can be printed using this system. As the computer can be re-programmed to provide any number of combinations in sequences with little waste of time, custom work can be easily handled. This process is one of the most sophisticated dyeing systems and is also known as the Millitron System. As the system requires a huge volume to make its operation economical, only a few carpet mills possess such equipment.
                  
                  
                  • Pad dyeing: This continuous dyeing process is also suitable for dyeing carpet. Refer to yarn pad dyeing above for details.
                
                
                • Carpet Colour:
                  
                  
                  • The technology of dyeing and printing is changing all the time. Even though the number of these different techniques of colouring and printing has produced an unlimited choice of colours and patterns in the market place, the demand for change in colours patterns and styles has resulted in little change in existing techniques or the evolution of newer production machinery. The carpet producer must weigh the capital cost of new machinery not only against remaining competitive but also against recouping his costs over the short period of time that a carpet colour or pattern might remain popular.
                  
                  
                  • Top colours in printed or woven coloured patterns are the ones forming the pattern elements, as distinguished from background or ground colours. A Ground colour is the background colour against which the top colours create the pattern or figure in the design.
                  
                  
                  • Colour fastness: This is the ability of a carpet or carpet fibre to retain its colour when exposed to detrimental conditions. The loss of colour or fading can be caused by a number of things: exposure to ultraviolet light, atmospheric conditions (i.e., gases including ozone, nitric oxide, and hydrogen sulphide); cleaning and bleaching chemicals (such as sodium hypochlorite and other household and industrial products), and/or wet or dry crocking (i.e. colour rubs off due to improper penetration or fixation of dyestuff). The retention of colour or colour fastness in carpets is influenced by the fibre type, as well as the dye and dyeing method used. Where fading is a distinct possibility (e.g., in carpet adjacent to windows) due care is required in the selection of a carpet / fibre with colour-fast colours.
                  
                  
                  • Fading tests: Laboratory tests have been developed to predict the likelihood of a carpet / fibre fading under actual use conditions. Carpet being considered for a critical installation should be tested in laboratory fadeometers for results against fading agents prior to final selection.
                    

2 • CARPET CONSTRUCTION

.01    Common Components: Although carpets are manufactured in many different ways there are certain components that are common to all carpets. The following terms are useful in understanding carpet construction.

.02    Ply: The number of yarns twisted together to form one pile yarn. The finished product or pile yarn is designated as one ply, two ply, three ply etc. Ply is not an index of quality          but must be considered together with the weight and size of the yarn. Ply of yarn makes a big difference underfoot, provided that the yarn weight is not reduced.

.03    Yarn Size: There are a number of methods of expressing yarn size (yarn count or weight of yarn). These include a direct numbering system using the denier method, as well          as tex and decitex methods and an indirect numbering system using the woollen count method, as well as the cotton and worsted count method. Denier refers to the number of          grams of yarn per 9000 metres and woollen count refers to the actual number of yarns per ounce. All of these systems are noted in item 1.07, Fibre Sizing and Weight above.

.04    Pile and Surface Yarn: These are the yarns which form the wearing surface of the carpet. The pile yarn may be cut, looped, or a combination of both. As a means of                      measuring the construction of carpet, the pile yarn refers to the wear layer, as well as the part "buried" in the backing, as in Wilton carpets.

.05    Warp Yarn: These are yarns which run lengthwise in the carpet backing (in the direction of production) and are of two types:

• Chain Yarn: The "chain" warp is referred to as the chain binder, because it binds all yarns used in construction together and runs lengthwise. The chain binder runs alternately over and under the weft binding or filler yarn and "pulls" the pile yard down and the stuffer yarn up, resulting in a tightly woven construction.


• Stuffer Yarn: The "stuffer" warp are yarns that run lengthwise giving the carpet extra strength and weight. In Wilton carpet, part of the pile yarns become warp yarns when they form part of the backing, running the length of the carpet.

.06    Weft Yarn: Also called "shots" are those yarns that run across the width of a carpet. The "weft" when combined with "warp" binds the pile yarn together to form the carpet.

.07    Pile Density: This is the number of tufts both across (needles per 100 mm of gauge for tufted carpet) and lengthwise (stitches per 100 mm) of the carpet. The weight of pile              yarn for any given area of carpet is a relative measure of pile density. The denser (more tufts per square inch) a carpet's pile (i.e., the closer the tufts are together) the less              weight each tuft will have to bear and as each tuft supports the other there will be more resistance to compression. Any weight is distributed more evenly over the surface of a          denser carpet and there will be less flexing of the pile. This results in greater crush resistance and longer wear.

Pile density is difficult to measure and some of the items that must be considered are:

• Yarn size (refer to 2.03 above).
• Stitch count.
• Pitch (for woven carpet) or gauge (for tufted carpet).
• Pile height.

.08    Weight of Pile Yarn: This is the weight of the pile yarn expressed in grams per square metre (or ounces per square yard). In appraising the wear life of a carpet, attention                  should be given to the total weight of the pile per unit area, e.g. per square yard or metre. When this factor is considered together with pile height, it will give a good indication          of a carpet's quality. The weight of the pile is dependent on the weight of the yarn, pile height, and how closely it is woven together.

         Published pile weight (per unit area, i.e. g/m² or oz/yd2) of a carpet includes the yarn above and below the primary backing and is usually measured under controlled                      conditions at the undyed / unfinished or greige level of manufacture before the addition of additional backings. Pile weight is subsequently reduced up to 35 g/m² (1 oz/yd2)              after the carpet is heated and stretched during manufacture. The same tolerance should therefore be deducted off the published weight to determine the actual weight.                      Consequently, the finished pile weight of loop carpet can, if tested, be as much as 70 g/m² (2 oz/yd2) lower than the published weight. In the case of cut pile and combinations          of loop and shear, additional pile weight is lost during the shearing process.

         Note: It is not realistic to demand carpets be increased to the published weights as this would mean a "special" production run.

.09    Pile Height : This is the thickness of the wear layer of a carpet and is measured from the top of the pile to the top of the backing. Pile height may vary according to the texture          of the carpet such as in cut and loop and high-low loop carpets, but in such cases an average measurement is taken. Yarn that goes through the backing does not count in pile          height.

.10    Tufts: A tuft is a length of yarn (either cut or one-half of a loop) resulting from a single penetration of the primary backing. In carpet construction the closeness of pile                          construction is determined by the number of tufts per inch. In tufted carpets this is a matter of totalling the number of tufts in a given area. In woven carpet however, the                      number of tufts is determined by the pitch and the rows per inch.

.11    Stitch Count: This term applies to tufted carpet only and refers to the number of yarn tufts per running inch in a single tuft row running down the length or longitudinal direction          of a carpet and is expressed in stitches per inch (spi) as opposed to gauge. The number of stitches per inch is determined by the number of needles as well as the space                  between the needles.

.12    Gauge: This term applies to tufted and knitted carpet and refers to the number of ends of surface yarn per running inch across the width of a carpet (e.g., 1/8 gauge = 8 ends          per inch.) as opposed to stitch count. In other words, it is the distance, in tufting, between two needle points expressed in fractions of an inch or needles per 10 cm. The higher          the number the coarser the carpet tufting. 1/10 gauge = 10 needles per inch (42 / 10 cm), 1/8 gauge = 8 needles per inch (32 / 10 cm).

.13    Pitch: This term applies to woven carpets only and refers to the number of ends of yarn in 27 inches in width. Pitch is the closeness of a crosswise weave or pile density                  across the width in a carpet and is based on the number of warp (length-wise) lines (based on the number of "reed" spaces in the loom) in a width of 27" carpet. If there are 8          ends per inch, the pitch of the carpet would be 216 (8 x 27). Pitch may vary with the type of weave but the higher the pitch the finer the weave. In 189 pitch (common for                  Axminster carpet) or 256 pitch (common for Wilton carpet) for example, this is the number of lines, i.e., 189 or 256 running through each 27" width.

         To convert gauge to pitch, multiply ends per inch by 27, e.g., 1/10 gauge is equivalent to 270 pitch, or 10 ends per inch x 27. 1/8 gauge is 8 ends of yarn per inch x          27 = 216 pitch. Refer also to "stitches per inch". .14

         Rows or Wires: This term applies to woven carpets only and refers to the number of weft shots or crosswise units per inch measured along the length of a carpet. This literally          means the number of pile tufts per inch lengthwise, and relates to the closeness of the weave. The number will differ according to the grade of carpet, and will range from 4 in          low density Axminster carpet to as high as 13 in densely woven Wilton carpet. Tufted carpets have no crosswise yarns, but it is still possible to measure the number of tufts per          inch by merely counting them.

.15    Shot: This term applies to woven carpets only and refers to the number of filling "weft" yarns shuttled across the carpet in relation to each row of pile tufts. A two shot                      construction is one in which two weft yarns have been carried across between the wires or rows. If there are three weft yarns between the 2 rows, it is called a three shot                  construction. The term "pick" applies to weft yarns, shuttled across the carpet between the warp yarns. The number of picks per inch indicates the closeness of the weave. A              fine quality Wilton carpet has three shots, times 8 wires, or 24 picks.

.16    Choice of Fibre: Both synthetic and/or natural fibre may be used in fabricating carpet yarn. As fibres differ considerably in many respects, such as abrasion resistance, twist              retention, compression resistance, resilience, stain resistance, wet cleanability, and static generation, due care and consideration must be given in the selection of an                          appropriate fibre for a carpet. A wool/nylon blend combines the superior look and comfort of wool with the durability of nylon. Acrylic/olefin and nylon/olefin are other popular              blends, offering good characteristics of each fibre.

.17     Surface Construction: Cut pile, or twist, or straight yarn, looped or round wire, or any combination of each, influences crush resistance, resilience, cleanability, and texture              retention. In general, round wire or looped construction is more functional than cut pile, but is more difficult to clean. On the other hand, round wire gives fuzzier details of                  design, while cut pile produces a more luxurious effect in sharp details.

.18    Body Construction: The form of carpet construction has a bearing on the maximum pile density that can be obtained. The fibres selected for the body of the carpet are also          important since they affect service life, shrinkage, and dimensional stability. Refer to 1.3.06, Fibre Properties for more details.

3 • CARPET CONSTRUCTION METHODS

.01    In addition to the type of fibre selected, the method of carpet construction also plays an important role in a carpet's performance. There are six (6) basic methods of                      construction used in manufacturing carpet:

• Tufting / tufted carpet.
• Weaving / woven carpet.
• Fusion-bonding / fusion bonded carpet.
• Needle-punching / needle punched carpet.
• Knitting / knitted carpet.
• Flocking / flocked carpet.

.02    Each of these construction methods has certain unique capabilities built into them. Some performance and styling features may be common to all construction methods                      however each should be checked for their own independent advantages and disadvantages.

• Tufted carpet: Tufting is the most common method of manufacturing carpet. This type of carpet is fabricated by punching tufts of face yarn through a prefabricated primary backing using needles much the same as a giant sewing machine having hundreds of needles and a needle bar. The yarn is threaded through each needle eye and the needle is pushed through the backing material. As the needle is pulled out a loop or tuft is formed and held in place by the backing. The depth of needle penetration determines the pile height of the finished product. If the yarn is not pre-coloured the carpet is dyed or printed after tufting.
• In tufted carpet, straight stitching places 5 to 10% of the face yarn below the primary backing. This may be increased up to 15 to 30% in patterned carpet.
  
  The tufts are permanently held in place on the back face by a variety of different methods such as coating the backing with latex (primary backing), and utilizing a secondary or unitary backing of fabric or vinyl, etc. Primary and secondary backings are normally woven or non-woven polypropylene fabrics although woven jute may still be used but in a limited way. The secondary backings are laminated by a coating of latex or hot melt adhesive, which is dried and/or cured in place. The secondary backing imparts dimensional stability, increases strength and fastens the pile yarn securely in place. An alternative to secondary backing is an attached cushion made of synthetic rubber foam, polyurethane foam or similar material. Plain coatings, referred to as unitary backings, may also be used in lieu of secondary backing or attached cushion. These backings generally consist of synthetic latex compounds although vinyl and urethane coatings are also used.
  
  One of the distinguishing characteristics of tufted carpets is the lengthwise direction of the rows of loops running across the width of carpet. The spacing between the tufts across the width and along the length of the primary backing can be controlled so that the number of tufts per cm² can be varied to provide a tight or loose pile.
  
  An alternative to the straight line stitch formation is the random effect created by equipment that shifts back and forth in a zigzag fashion or by the more effective Displacement Needle Bar, sometimes called "Stepover" or Sliding Needle Bar.
  
  The tufting process produces carpets with pile that is either looped, cut, or a combination of both, in a single pile height or in multi-level effects. Despite the fact that loop piles have tended to dominant the contract market since the advent of tufting, there is no particular magic to this construction type. Today's increased spinning speeds and continuous heat-setting techniques, together with the possibility of using filament yarns, have made cut-pile constructions more competitive. Patterns may be tufted into the carpet through yarn placements and pile yarn shifting mechanisms or applied though after-printing or other dye techniques. Further textural features are achieved through the choice of pile yarns. The styling of commercial carpets has been greatly enhanced by these tufter patterning modifications, making possible a wide variety of geometric and abstract multi-colour effects. The most recent developments, allowing even greater control of yarn placements, are broadening still further the pattern capabilities of the tufting process.
  
  
  Gauge of Carpet: Tufted carpets are not only defined by the weight of yarn but also by the number of stitches.
  
  The following is a conversion scale used to convert the machine gauge to number of needles used in 100 mm (4").
  
  Machine Gauge 1/16 5/64 3/32 1/10 1/9 1/8 9/64 5/32 3/16 1/4 5/16 TO Needles / 100 mm 63.0 50.4 42.0 39.4 35.5 31.5 28.0 25.2 21.0 15.8 12.6 Quality: The quality of a tufted carpet depends on a number of factors such as yarn quality, amount of pile per unit area (density), quality of backing material, and the thickness and quality of the applied coating or system.
  
  Comments: Increased manufacturing speed resulting in reduced cost of producing durable, luxurious carpet in a wide variety of patterns and textures but some pattern, style, colour limitations when compared to woven carpet.
  
  
  • Woven Carpet: This is the oldest form of manufacturing carpet. The weaving process is a slow one in comparison to tufting and the unit cost of similar quality carpet is therefore higher and has limitations with tufting styles and textures impossible to duplicate. This type of carpet is woven on a loom where the lengthwise yarns and width-wise yarns are interlaced to form the fabric, including the face and the backing simultaneously. The four most common types of woven carpets are:
    
    
    • Axminster carpet: a cut pile carpet that is woven on an Axminster loom where pile tufts are individually inserted from spools of coloured yarns. This complicated weaving process is used chiefly for complex multi-coloured patterned cut pile carpet and rugs. It is similar to the weaving and hand knotting process used in oriental carpet production. A distinguishing feature of Axminster carpet is a heavily ribbed backing which can be rolled length-wise but not width-wise
    
    
    • Comments: High performance carpet with luxurious styling and wide variety of design and colours available although plain colours are not generally made. Carpet is labour intensive and slower to produce and requires special knowledge and skill to install.
      
      There are three types of Axminster carpet:
      • Spooled Axminster carpet is made using spools of yarn that are locked together end to end in a frame that stands across the width of the loom. The sequence of yarns on the spools determines the pattern. Using a shuttle which extends the width of the loom, the backing yarns are inserted to lock the tufts in place. Through the use of individual spools it is possible for every tuft to be of a different colour thus allowing an unlimited scope of designs and colours.
      
      
      • Gripper Axminster carpet is made similar to spooled Axminster except that the yarn is selected by individual grippers before insertion and is usually restricted to a maximum of eight yarn colours at one time. Controlled by a Jacquard punched card system, one complete row is put in place at a time. This carpet is produced in 27" widths that are then sewn together
      • Chenille (Axminster) carpet, a third type of Axminster carpet, requires the use of a much more intricate weaving method to produce a high quality luxurious carpet. As a result of the additional manufacturing expense, this type of carpet has virtually disappeared from the North American market.
        
        
    • Wilton carpet: This weaving method utilizes a Jacquard attachment and a frame or creel from which yarn is drawn into the loom to form the pile of loop-pile carpets. The yarn is provided continuously with that which is not needed for the next surface tuft "buried" in the backing. This method also allows for greater density of fibre and the secure placement of individual tufts. Each colour of yarn is mounted on a separate frame and therefore yarns of different colour can be fed into the loom. While dozens of combinations are literally possible, no more than five colours are commonly utilized at one time. The use of a variety of yarns will produce different surface effects.
    
    
    • Comments: A close pile, high-performance / hardwearing carpet with solid backing and luxurious styling available in a wide variety of designs and colours. The carpet is labour intensive and slower to produce and also requires special knowledge and skill to install.
      
      
      • Velvet carpet: This type of woven carpet utilizing the same basic construction as Wilton carpets but without the "buried" yarn. This is the simplest form of weaving with the backing woven at the same time as the face or surface yarns which produces a carpet with excellent tuft bind and density. Velvet carpet is typically a cut pile or a level loop carpet in solid colour although blended yarns may be used to produce "moiré" or tweed textures and patterns. Velvet carpet may also be referred to as plush carpet. This type of velvet carpet has a luxuriously smooth-textured (single-level) surface in which individual tufts are only minimally visible with the overall visual effect of a single level of yarn ends. This finish is normally achieved only on cut-pile carpet produced from non-heat-set singles yarns by brushing and shearing. Sometimes called "velvet-plush." Plush carpet is lower and denser than a Saxony carpet and each yarn end is less distinguishable than in a Saxony.
      •  Comments: High performance and luxurious styling with a wide variety of designs and colours available, however carpet is labour intensive and slower to produce and   also requires special knowledge and skill to install.
        
        
        • Crossweave carpet: This woven carpet is produced by a "patented / proprietary" (e.g. Karaloc, Crossloc) weaving process whereby the pile yarns are woven through the back. The "sideways" pile orientation provides a strong resistance to edge ravel. For added protection a back coat of latex is applied to give a positive tuft bind and to impart additional dimensional stability to the product.
        
        
        • Comments: High performance and luxurious styling with a wide variety of designs and colours available, however carpet is labour intensive and slower to produce and also requires special knowledge and skill to install.
        
        
        
        
      • Knitted Carpet: Somewhat similar to weaving in that the face and back are formed simultaneously. It is not similar in that the carpet is made by looping the backing, stitching and pile yarns together by using three sets of needles operated by the machine. The finished back is usually latexed to provide stability and body. A secondary backing may also be applied. Recent modifications permit a broad range of design, texture and finish variations in loop and cut pile stylings.
      •  Comments: Resilient and crush resistant carpet (often used in vehicles and aircraft) with limited designs and textures that is relatively time consuming to produce and install.
        
        
        • Needle Punched Carpet: This type of carpet is fabricated using a process that involves the compression and entanglement (by means of barbed needles) of batts of staple fibres. Through different needling techniques various surface textures may be achieved. A woven scrim carrier may be included to give extra strength and stability and the structure may also be impregnated with latex to further bind the fibres. Some needle punched carpets are made from pigmented polypropylene fibres, stabilized for outdoor use. If made from fibres such as nylon they may also be printed.
        • Comments: Durable carpet that will not zipper but with very little design flexibility and texture.
          
          
          • Fllocked Carpet: This type of carpet is manufactured by embedding very short chopped fibre or flock on a prefabricated backing to which an adhesive coating has been applied. The electrically charged precision cut fibres are perpendicularly aligned electrostatically on the backing creating a densely packed, velvet-like finished pile.
          • Comments: Highly resilient and crush resistant carpet (often used in vehicles and aircraft) but with limited designs (although verify with manufacturer).
            
            
            • Fusion Bonded Carpet: This type of carpet is fabricated using a process that produces a completed carpet by embedding yarns in a primary backing that is then coated with a liquid vinyl compound that hardens to form the backing giving the carpet an exceptionally strong tuft bind. Alternatively, the pile material can be implanted between two coated backings forming a sandwich, which is then sliced through the centre of the yarn to form two identical cut pile carpets. This type of carpet is available in wide widths and modular form and may be produced in either cut or loop pile.
            •  Comments: Durable, moisture resistant carpet with high tuft bind, and other benefits depending on the type of backing used. Restricted in type and sizes (cut pile carpet in 6'   or module form / spun yarn only) and requires special adhesives and installation techniques.
            
            
            
            
            .03    Other Types of Carpet Construction:
            • Modular or Tile Carpet: Carpet produced in module form (typically square) usually complete with a structured backing of polyvinyl chloride (PVC), amorphous resin or of other polymeric compounds and which may also include an integral cushion. Backings may also be moisture impermeable. The size of module (tile), construction, backing system and method of installation varies from manufacturer to manufacturer. Modular carpet can be installed with standard adhesives, releasable adhesives, and peel-and-stick adhesives, mill applied.
            
            
            • Comments: This type of carpet offers unique design advantages in patterns and colours and can be selectively replaced, relocated or rotated to suit wear and maintenance requirements and offers immediate access to under floor utility conduits in raised floor systems. With multiple joints however there is increased potential of edge curl or edge lifting due to adhesive bond failure as well as edge fraying or fuzzing.
              
              
              • Specialty Carpets: A variety of specialty carpets are marketed. These types are usually hand made with some machine made and include hooked, knotted, braided and other hand made rugs. Styles and patterns range from plain coloured rugs, to intricately patterned hand carved carpets and come in many sizes, ranging from small area rugs to large (wall to wall) carpets.
                
                
              • Comments: Carpet can be made to order to suit room size and in desired colours and textures however this may result in additional costs.
                
                
                • Electrostatic Discharge (ESD) Carpets: A type of carpet specifically designed to meet the requirements for an ESD-controlled environment where the static generated by walking on the floor must typically be less than 0.2 kV (200 volts). This carpet incorporates electrically-conductive elements (e.g. carbon filaments in fibre) that are connected to a conductive backing. The carpet is glued to the floor with a special conductive adhesive that is carefully connected to the building ground at specified intervals. This carpet is generally restricted to applications involving electronic-component assembly or where electronic components and/or circuit boards are routinely handled. The use of electronic equipment, computers, digital phones, etc., in a typical commercial space does not require the use of ESD carpet, as long as permanent static control is built into the commercial carpet product.
                
                
                • Comments: Carpet can be made to order to suit requirements, however it is seldom used or manufactured anymore due to expense and changing electronic environment requirements.
                  
                  Note: An ESD-controlled environment requires the use of special ESD shoes, and generally includes the use of electrically-grounding wrist straps, special grounded work surfaces, ESD smocks over clothing, and control of humidity within the range of 40-60% RH.
                  
                  
                  • Carpet for Exterior or Speciality Applications: Only carpets designated for outdoor or indoor/outdoor use and specifically classed as such can be used in these applications.
                  • Comments: Advantages and disadvantages must be verified with manufacturer.
                  
                  
                  
                  
                  .04    Carpet Texture
                  • Texture, next to colour, is one of the most important considerations in selecting a carpet. Texture may be described in such terms as smooth, plush, velvet, firm, rough, coarse, nubby, tight, loose, etc. Texture (as well as pattern) will determine a carpet's appearance and pile retention. Although durability has a direct bearing on appearance after a number of years of usage, a less durable carpet will still look good if the correct style is chosen. High twist, low pile, and tight gauge carpets are extremely practical and will retain their look after many years of wear. The same can be said about heavily patterned carpet that can hide worn-out areas as well as stains that have become difficult to remove. Plushes (and loosely woven shags), particularly in light colours, can really look unbecoming with little exposure to traffic.
                  
                  
                  • There are a number of carpet textures to be considered, each with its own look, feel and advantages:
                    
                    
                    
                    • Cut Pile Carpets: This type of carpet with cut loops, leaving individual yarn tufts, is still one of today's most popular constructions. It is known for its durability which is achieved with factors including the type of fibre, density of tufts, and the amount of twist in the yarn. There are a number of styles:
                    
                    
                    • Velvet Carpets: A cut pile carpet with short upright standing yarns that form an even, dense velvet-like surface, creating a formal atmosphere. Individual yarn ends are not visible. May show footprints and vacuum marks. Refer to Figure No. 04.1.4 above.
                    • Plush Carpets: Similar to velvet carpet except with higher upright standing yarns. May show footprints and vacuum marks. Refer to Figure No. 04.1.4 above.
                    • Saxony Carpet: A cut pile carpet with a smooth, level finish, similar to plush / velvet carpets but less dense and with more twist to yarns so that the yarn ends are visible. This style creates a less formal look and minimizes footprints and vacuum marks. Textured Saxony carpet (yarns are twisted not straight and at varying heights) is less likely to show footprints and vacuum marks. Refer to Figure No. 04.1.5 above.
                    • Hard Twist Carpet: A cut pile carpet with short, tightly twisted upright yarns.
                    • Friezé Carpet: A cut pile carpet similar to hard twist but with extremely twisted yarns that form a "curly" textured surface, creating an overall knobby effect. Sometimes referred to as "popcorn" carpet. This informal look also minimizes foot prints and vacuuming marks. Refer to Figure No. 04.1.6 above.
                      
                      
                  • Loop Pile Carpet:
                    • Level Loop Carpet: A carpet with uncut loops all of equal height, making a smooth and level surface and creating an informal look. This type of carpet generally lasts a long time in high-traffic areas. Some large loop Berber carpets fit into this category. Refer to Figure No. 04.1.1 above.
                    • Multi-Level Loop Carpet: A carpet made up of different height loops, with two or three heights being common. The difference in heights creates a textured effect and a more casual look. This style provides good durability. Refer to Figure No. 04.1.2 above.
                    • Berber Carpet: The name originates from handmade, bulky wool carpets made by the Berber tribes of North Africa. Commercial Berber carpet is now made from thick or bulky yarns of wool, nylon, olefin or a blend of these fibres in level loop or multilevel loop form, and is available in an assortment of colours. Refer to Figure No. 04.1.3 above.
                    
                    
                    
                  • Combinations of Cut and Loop Pile Carpet Interesting carpet testures can be created by using combinations of cut and uncut loops. There are variety of types.
                    • Cut and Loop Pile Carpet: A carpet having a combination of cut and looped yarns that provides a variety of surface textures, including sculptured effects of squares, chevrons, swirls, etc.
                    • Tip-Sheared Carpet: A carpet with a level surface with cut and uncut loops of the same height. This creates a more luxurious effect than level loop carpet. Refer to Figure No. 04.1.7 above.
                    • Carved and Sculptured Carpet: These types of carpet designs are achieved by cutting away part of the face yarns to create definite textured patterns.
                    • Sculptured Cut and Loop Carpet
                      • Random Sheared Carpet: A carpet made by cutting off the tops of the highest loops to create a random texture. Refer to Figure No. 04.1.8 above.
                      • Shag Carpet: Shag carpet is made from lower density cut loops of long pile yarns. Refer to Figure No. 04.1.9 above.
                  
                  
                  • .05    Carpet Patterns
                    • Patterned carpets provide colour and variety. Many are available from the manufacturer's standard range, unless a custom pattern is specifically required. The following overview describes how patterns in carpet are created.
                      
                      Patterned Loop
                      • Using pre-coloured or pre-dyed yarns, patterns may be created in any of the following construction methods:
                        • Woven carpet (Axminster, Wilton, and Velvet weave).
                        • Tufted carpet (using graphics or various computer controlled techniques)
                        • Knitted carpet
                      • Patterns can also be produced after the carpet is woven or tufted using undyed yarns with the pattern applied afterwards (a post-dyeing method). Commonly used post dyeing methods are:
                        • Screen printing (flat and rotary).
                        • Injection dyeing (using computer controlled processes with colourant injected into the carpet pile).
                    • Patterns created by the tufting process, tufted graphics, as well as screen printed and injection dyed carpet, require processing and finishing after the pattern is created. All of the subsequent finishing processes affect the size, straightness, and squareness of the pattern.
                    
                    
                    • Regardless of the method of construction, slight variations in yarn tensions, yarn feed, etc. can create changes in pattern configuration.
                    
                    
                    • Pattern Variation: Variation in pattern may be found in any patterned carpet. These can be characterized by four conditions
                      • Pattern Bow: wavy or crooked pattern lines when viewed across the seams.
                      • Bias or Skew: squareness of the pattern
                      • Pattern Repeat (or run-off): mismatching or uncorrected pattern variations across the width or along seam lengths
                      • Trueness of Edge: wavy or serpentine pattern lines when looking down the length of the carpet.
                      • The possible existence of all these variations must be considered when specifying and bidding any project where broadloom patterned carpet is to be installed.
                      
                      
                      
                      
                    • When selecting patterned carpet the following should also be considered:
                      • Large patterns tend to decrease the apparent size of an area.
                      
                      
                      • Large expanses of floor space generally require larger and bolder patterns. When placed in a large room, such as a ballroom, smaller patterns tend to lose definition and will have the appearance of a tweed. Smaller patterns are best used in smaller areas and where there are fewer seams.
                      
                      
                      • The larger the pattern, the easier to match and install.
                      
                      
                      • Patterns with high degree of linearity, such as plaids or stripes, present more difficult installation challenges.
                      
                      
                      • It is highly recommended that carpet with width wise linear patterns not be installed breadth-to breadth along the length of a corridor.
                    
                    
                    • Factors affecting acceptable pattern matching on the job site can include, the method of installation, the condition and levelness of the substrate, and the type of carpet backing system. Because of this it is imperative that realistic levels of expectation be clearly agreed upon between all parties (i.e., between the carpet manufacturer / supplier and the design authority and Owner) before the carpet is installed.
                    
                    
                    • Even though the Canadian Carpet Institute publishes an industry standard for pattern variation, the carpet manufacturer should be responsible for providing a written specification before installation as to the degree of variations expected, the degree of installed mis-match (if any) considered acceptable, and any guarantees or warranties of pattern match offered.
                    
                    
                    • The carpet manufacturer's material ordering allowances (for both pattern matching and overages) and specific installation tolerances must be clearly understood, communicated, and agreed to by all parties prior to specifying, bidding, ordering, and installation of all patterned carpet.
                    
                    
                    • Because of the above noted factors, patterned carpet should only be installed by skilled, responsible and competent installers experienced in the installation of patterned carpet using power stretchers and methods specified by the carpet manufacturer. Because patterned carpet requires more time and expertise and often additional installation personnel, the cost of installation will be affected.
                    
                    
                    • Successful installation of patterned carpet requires a thorough understanding of its characteristics by all parties involved in the selection and installation process.
                    
                    
                    • When planning the installation of patterned carpet the following must be noted:
                      
                      
                      • Although exact pattern match is usually not guaranteed, manufacturers will provide tolerances and specific installation instructions
                      
                      
                      • The installation method selected may influence the degree of pattern adjustment that can be realistically expected. The amount of adjustment possible will vary with the backing system selected.
                      
                      
                      • Pattern adjustment during installation is possible and expected.
                      
                      
                      • Relaxing (acclimatizing) the carpet by unrolling it in a room for 24 hours under controlled conditions will help facilitate adjustment for pattern variations.
                      
                      
                      • Power stretchers and stay nailing are commonly required even in glue-down installations.
                      
                      
                      • Time requirements, thus labour costs, will not be the same as for installation costs of plain carpet.
                    
                    .06    Carpet Backing
                    
                             Carpet backing consists of either one (primary) or two (primary and secondary) layers depending on the carpet type. Primary backings hold the carpet tufts in place. A                      secondary backing, which is glued to the primary, is added for additional stability.
                    
                    
                    • Primary Backing: This is a pre-fabricated tear resistant "fabric structure" into which the carpet's face fibres or tufts are inserted by tufting needles and is predominantly used in tufted carpets. The backing provides dimensional stability and is usually manufactured from woven or non-woven synthetic (usually polypropylene) although in some cases natural fibre may still be used. Sometimes the manufacturer colours this backing material to match the carpet yarn to "hide" the backing from the topside and for a "denser looking" appearance.
                    
                    
                    • Backing Laminate: This material is usually a mixture of styrene butadiene rubber (SBR) latex polymer and mineral filler in liquid form that is applied over the primary backing (i.e. to the back of greige carpet which is upside down at this stage) to encapsulate the yarn fibres and primary backing and just prior to addition of the secondary fabric backing. In the past, some latex-based backing laminates have been found to crystallize as early as five years after installation, resulting in premature delamination. A soft-set no-VOC SBR latex type is now available that may not crystallize as quickly, however carpet with this material may become more difficult to remove over the same period of time.
                    
                    
                    • As moisture degrades SBR latex laminates, carpet with this type of backing laminate should not be subjected to frequent and extensive exposure to moisture. To improve a carpet's moisture resistance, increase tuft bind and reduce delamination, PVC or polyurethane based backing laminate can be used. Where moisture, hygiene, or heavy rolling traffic is a concern, a different, moisture impervious backing system should be used.
                      
                      If the backing laminate does not adequately encapsulate the yarn fibres, the face yarn may exhibit "bearding" or fuzzing which in time may result in a degraded surface appearance. Because of this some manufacturers apply a separate liquid pre-coating that better penetrates yarn to improve fibre encapsulation.
                      
                      Conductive materials can be added to backing laminate to provide static control. Refer to electrostatic discharge (ESD) carpets above (03.0).
                      
                      
                      • Secondary Backing: Sometimes called double backing, this is an additional backing that is attached / laminated to the underside of tufted carpets for additional dimensional stability, greater tuft bind and body, and to facilitate carpet removal. Secondary backing may be woven jute, woven or non-woven synthetics (e.g. polypropylene), scrim, foam, or cushion.
                      
                      
                      • Backing Materials: As indicated, a variety of materials are used either singularly or in combination for carpet backings. These are:
                      
                      
                      • Woven Natural Materials: Jute is the leading natural material used as it is strong, durable, and resilient, however it may mildew in damp conditions. Other natural fibres include cotton, kraft cord (tightly twisted yarn made form wood pulp), and rayon.
                      • Woven or Non-Woven Synthetic Materials: More than 90 percent of carpet backings are made of woven or non-woven polypropylene as it is strong, durable, and resistant to mildew. Other fibres used are polyester.
                      • Solid or Expanded Cellular Backing Materials: These may be:
                        • Latex.
                        • PVC (vinyl).
                        • Thermoplastic (resin).
                        • Polyurethane (foam and laminate).
                        • Composite (solid) and expanded (cushion) rubber.
                          
                          
                    • Backing Systems: There are a number of backing systems that utilize the above noted backing materials in a variety of ways:
                      • Conventional tufted backing: separate primary and secondary latex laminated woven or non-woven fabric backings.
                      • Woven carpet backing: a backing composed of carpet construction yarns consisting of the warp chain, stuffer warp, and shot or filler yarns, all of which are simultaneously interwoven with face yarns (carpet pile) during carpet manufacture. Adhesive with sizing (backcoat) is usually applied to the back of woven carpet.
                      • Resin bond backing: a hot melt resin process that adheres the primary and secondary backing resulting in increased tuft bind, edge ravel resistance, and secondary backing adhesion.
                      • Unitary backing: a primary backing only (i.e., there is no secondary backing) consisting of a high rubber content latex or a hot melt resin compound which provides increased tuft bind and inhibits zippering. Unitary backing is used primarily with loop pile carpet and for glue-down installations.
                      • Urethane (foam) backing: an organic coating applied to the back face of carpet during the finishing process which when heated and cured creates a cushion foam that encapsulates the yarn providing increased tuft bind, and inhibits zippering. It can also be applied or laminated to the secondary backing of a "completed" carpet.
                      • Vinyl (PVC) backing: a heat cured closed cell PVC (polyvinyl chloride) layered coating with or without (fibreglass) scrim reinforcing which provides a moisture resistant backing with increased tuft bind and dimensional stability. Due to its weight and stiffness it has little cushion effect. Generally used in fusion bonded and modular carpet or 1800 mm (72") wide goods. There are three types:
                        • PVC tufted carpet: backed with PVC that is reinforced with fibreglass scrim or sheets. These products require a 100% spread of releasable adhesive for proper performance. 1800 mm (72") wide PVC carpet may be installed with permanent adhesive and seam welded to provide a full width moisture protection installation.
                        
                        
                        • PVC bonded carpet: a fusion bonded carpet backed with PVC that is reinforced with two layers of fibreglass sheets. These products may be loose or free laid (i.e., without glue) or over a grid application of glue, as differentiated from a full glue spread installation.
                        
                        
                        • PVC foam backed carpet: similar to PVC bonded carpet but with a closed cell PVC foam backing that may be compared to "bubble wrap" giving a "pneumatic" action that is completely dependent on the small bubbles of air trapped within the PVC. Over time the bubbles can rupture, particularly in areas of heavy traffic resulting in cushioning loss. The use of PVC foams for cushioning is largely restricted to applications where cost is a primary concern and performance a secondary issue.
                      
                      
                      • Note: Due to the variety of backing systems as noted above, each carpet (backing) must be installed in strict accordance with the manufacturer's requirements. This also includes using appropriate adhesives and trowels.
                        
                        Note: Backing systems (other than tufted and woven types) typically don't delaminate but may delaminate from the substrate they are adhered to due to the texture of the backing. These usually require different trowels and an adhesive that develops high bond strength quickly. Removing carpet with such backings can be considerably more difficult due to the amount and quality of adhesive required during installation.
                      
                      
                      
                      
                    .07    Carpet Edge Binding and Serging:
                    
                    
                    • Carpet binding and serging is used on exposed carpet edges of loose carpet (without edge trim) and area rugs, door mats, hall and stair runners, and for exposed tops of carpet base to strengthen and protect them from unravelling and fraying. In some cases carpet base may be ordered with edging as well as with an adhesive backing system.
                    • Carpet binding: This procedure entails sewing a narrow band or strip of material (usually a nylon or cotton "tape" in a complimentary colour) over the edge of the carpet and through the backing using a zigzag double lock or straight lock stitch and may be sewn off-site (in shop) or on-site using a portable binding machine. An older method of binding included gluing and stapling coloured tape to the carpet edge but this method is falling out of practice due to the labour involved. Binding may also be used to decorate carpet edges.
                    • Carpet serging: This procedure (also known as over sewing) entails sewing a heavy, coloured yarn around the edges using a close, overcast stitch and is frequently used on Oriental, Berber and sisal carpets / rugs and on carpets that are too heavy to feed through a binding machine.

4 • CARPET PERFORMANCE

.01    Carpet Performance Issues:

• Potential Wear Areas: Within any area the amount of foot and rolling traffic has an impact on a carpet's long term performance and appearance retention. In this regard the following "problem" areas require special consideration when selecting an appropriate carpet:
  
  
  • High wear areas: traffic lanes, pivotal traffic areas, such as turns or jogs in corridors; and concentrated traffic zones, such as those guided by ropes or stanchions.
  • Wet traffic areas: freshly cleaned carpet, entry areas, and areas around drinking fountains or sinks.
  • Heavy roller traffic areas: caster chairs, money carts, portable equipment, and motorized carts.
  • Extended standing areas: such as bank teller positions and sales counters.
  • Transition areas: between different types of floor coverings.


• Foot Traffic: To determine the effect of traffic on carpet it is necessary to first define what traffic is. A definition was established that defines foot traffic as a pedestrian walking across a measured section of carpet, one time. Using this definition the amount of foot traffic was then classified as follows:
  
  
  • Light traffic: based on up to 50 traffics per day that also includes some directional traffic but no tracked-in dirt.
  • Moderate traffic: based on 51 to 200 traffics per day that also includes some directional and non-directional traffic, some pivoting, and a little tracked-in dirt.
  • Heavy traffic: based on 201 to 1,000 traffics per day that also includes some directional, non-directional and rolling traffic, some pivoting, and tracked-in dirt.
  • Extra heavy traffic: based on over 1,001 traffics per day that also includes some directional, non-directional and rolling traffic, pivoting, and tracked-in dirt.


• Other Issues Affecting Carpet Performance: Other than foot traffic there are other issues that affect a carpet's long term appearance and performance. These are:
  • Soiling.
  • Staining.
  • Fading.
  • Static.
  • Microbial growth.

.02    Carpet Performance Testing:

• To determine the effect of traffic, soiling, staining, and fading a number of tests and guideline standards are used to determine carpet performance and appearance retention. These are:
  • Accelerated Wear Testing: A number of testing methods have been developed that use mechanical action within a rotating drum (approximating individuals walking on carpet for a specific number of steps or foot traffic counts) to produce changes in a carpet's surface structure and colour. After a specified number of traffic counts are completed (i.e. drum rotations), the samples are visually graded by comparison with Appearance Change Grading Scales supplied by the Carpet and Rug Institute. The scales indicate specific (appearance) ratings based on the carpet's ability to withstand crushing and matting over a specific duration (minimum drum cycles). These tests are:
    • ASTM D5251 or Tetrapod Walker Drum Test: Similar to Hexapod test.
    • ASTM D5252 or Hexapod Drum Test: Primarily used in Canada and based on a minimum of 12,000 cycles.
    • ASTM D5417 or Vettermann Drum Test: Primarily used in the US and based on a minimum of 22,000 cycles.
  
  
  • Soil Resistance: Soil resistance is the ability of a carpet to resist dry soil and maintain its original appearance after intermittent or restorative cleanings. This may be determined by testing based on an average of 3 fluorine analyses to CRI TM-102, of a single composite sample with a minimum of 500 ppm fluorine by weight and a minimum of 400 ppm fluorine by weight after 2 AATCC 171 (Hot Water Extraction) cleanings.
  
  
  • Stain Resistance: Stain resistance is the amount of stain absorbed into the fibre. A number of tests are used to determine resistance to stains with results based on International Gray Scale for Staining (a standard comparison to rate degrees of staining from 5 (no stain) to 1 (severe stain) and/or Red 40 Stain Scale (a standard comparison to rate degrees of Red Dye 40 staining from 10 (no staining) to 1 (severe staining). A minimum AATCC Red 40 Stain Scale rating of 6 should be specified if staining is a concern or a rating of 8 should be specified if staining is an important issue
    • AATTCC 138 Stain Test: a wet cleaning (shampoo) test based on 5 washings to simulate removal of topical treatments by hot water extraction. This test can be used for the evaluation of wet-fastness durability and permanency of antimicrobial properties, colourfastness behaviour, permanency of finishes, and other topical treatments before, during, or after manufacturing, and for cleanability and dimensional stability.
    • AATTCC 175 Stain Test: a stain test intended for use on pile carpet to determine the resistance to staining by acid food colours. A specimen of carpet is stained with a small volume of a diluted aqueous solution of Red 40 dye adjusted to an acid pH. After allowing the stained specimen to remain at controlled conditions for 24 ± 4 h, it is rinsed in water to remove all unused Red 40 dye. Any residual stain is assessed after drying.
  
  
  • Fade Resistance: Fading is usually caused either by ultraviolet light or by exposure to ozone or nitrogen oxide gas. Carpet is tested in the laboratory using a fadeometer, a standard laboratory testing machine that uses light, gas, or ozone to conduct fading tests for results against fading agents. Dye stuff, hue, or fibre can affect fading. A specific carpet being considered for a critical installation should be tested prior to final selection.
    
    
    • Lightfastness Fading Test: Fadeometer test (AATCC 16E) using an arc lamp that contains a special gas, xenon, which produces an intense light that accelerates the colour fading reaction. The test measures lightfastness in relative test hours. For conventionally dyed nylon, an International Gray Scale for Colour Change rating after 80 AFUs should be no less than 3. For solution dyed nylon, an International Gray Scale for Colour Change rating after 160 AFUs should be 3-4 or better. For direct sunlight exposure areas such as atriums, 4 or better may be required.
    
    
    • Atmospheric Fading Tests: Fadeometer tests (AATCC 129 - Ozone and AATCC 164 - Oxides of Nitrogen) that indicates a change of shade or hue of dyed fabric caused by a chemical reaction between certain dyes and acid gases. Recommended test methods for carpets would specify a minimum rating, after two cycles, of no less than International Gray Scale for Colour Change rating of 3.
  • Note that cleaning and bleaching chemicals such as sodium hypochlorite, and other household and industrial products can also fade a carpet.
    
    
    • Colourfast Rating: Colourfastness is a carpet yarn's ability to retain its original colour. Colour may be lost due to exposure to light or atmospheric contaminants or by rubbing off when wet or dry.
    
    
    • International Gray Scale for Colour Change: This is a standard comparison to rate degrees of colour change from 5 (no change) to 1 (severe change).

.03    Carpet Appearance Retention Ratings:

• Carpet performance ratings (PR) are an important and useful tool to assist an Owner or design professional in choosing an appropriate carpet for any given area.


• Appearance Retention Ratings (ARR) using the above noted accelerated wear testing methods have been established and are used by many carpet manufacturers to identify the level of appearance change of their carpets resulting from foot traffic. The appearance changes are graded using the Appearance Change Grading Scales supplied by the Carpet and Rug Institute after the test's specified number of traffic counts are completed. For example, ARR values for carpet manufactured in the United States are determined by testing a carpet sample using the ASTM D-5252 (Hexapod) test practice after 22,000 cycles. (Note carpets are tested without cushion).


• The ARR scale identifies change-in-appearance on a 1 to 5 numbered scale for commercial carpet where 5 represents no change in appearance, and 1 represents a very severe change. The ARR indicates the amount of surface appearance retention expected in a given traffic area during the first year of service. Carpet with a higher ARR, such as 4.5 or 4.0, will retain its original new appearance longer in various traffic conditions than a carpet with a lower ARR. A 2 to 3 rating is good for areas with less traffic. Other systems may use a 10 point scale with 8 to 10 being the highest.


• Although not all carpet manufacturers provide this numerical rating, those who do believe it to be useful to the consumer in making an appropriate selection for the particular area under consideration. For instance, heavy traffic through narrow traffic lanes, such as a hallway, would need a carpet with a high performance rating in that area. Alternately, low trafficked areas would require a lower rating. In regard to ARR ratings the following minimum ratings are recommended:
• ≥2.5 ARR for application in a moderate traffic end use.
  ≥3.0 ARR for application in a heavy traffic end use.
  ≥3.5 ARR for application in a severe traffic end use including stair applications.
  
  
  • Individuals should keep in mind that these ARR numbers represent the expected appearance change to the surface of a carpet, including such conditions as crushing, matting, fuzzing, and loss of definition of the tuft tips. Other characteristics, such as soiling potential, abrasive wear, and colour loss, are not assessed in establishing a carpet's performance rating. In addition the ARR testing does not reflect the potential influence of variable factors such as soiling, staining, maintenance, and installation.
  
  
  • Also of note is that these ARR guidelines are not applicable to rugs, needled textile floor coverings with pile, or electrostatically flocked textile floor coverings.
  
  
  • For the ARR rating to apply, carpets must be correctly installed following manufacturer's instructions and in accordance with CRI 104 requirements. In addition, continuing maintenance must be in accordance with the carpet manufacturer's recommendations.
  
  .04    Carpet Protection:
  
  
  • There are a number of important properties being incorporated by fibre material and carpet manufacturers to enhance a carpet's performance and appearance retention in regard to soil and stain resistance, anti-static control, and as a deterrent to microbial growth. There are two basic methods of providing such protection:
    
    
    • Topical treatments: this treatment method uses a topical liquid or foam spray applied after carpet production. This type of chemical treatment is not permanent as it can be worn off with foot traffic, removed by successive cleaning, and it can be masked by residues left by cleaning. In addition most topical treatments contribute toward carpet surface soiling in the long term.
    
    
    • Inherent Treatments: These treatments are added during the fabrication of the fibre so that they become an inherent and permanent part of the fibre.
  
  
  • Soil and Stain Protection: Various methods are used to provide soil and stain resistance. These can be an integral life-long stain proofing, i.e., inherent in or permanently bonded to the carpet fibre, or a topical treatment applied to the carpet (fibres) after production.
    
    
    • Topical Soil and Stain Treatments: These treatments add surface tension to the fibre that cause spills to bead up on the surface of the fibre. This property acts much in the same manner as the Teflon coating on a frying pan. Spills are repelled by this treatment and many spills can be removed, if removal is attempted immediately. Dry soil is repelled in much the same manner, allowing the soil to release more easily, thus improving cleaning results.
    • The technology of how these topical soil and stain treatments work is really quite simple. In the case of stain treatment, they work in a similar manner in which dyes attach to carpet fibres. Fibres have dye sites that allow dye to penetrate the fibre. In fibres, these dye sites have a positive electrical charge. Dyes, having a negative electrical charge, are applied to the fibres and these opposite charges neutralize one another. This allows the dye to bond to the fibre. Many food items like Kool-Aid®, and Gatorade® use the same negatively charged dyes to add colour to the drink. When spilled on untreated fibre, these dyes bond to the fibre in the same way as dyes used in colouring fibres. This bond results in a permanent stain.
      
      The principle of stain-resistant chemistry is such that in dyeing carpet fibres, not all dye sites are neutralized by the dyes. These positively-charged dye sites remain available to accepted unwanted dyes. In essence, a clear colourless dye is added to the carpet face fibre after dyeing which neutralizes all remaining dye sites and limits the acceptance of new dyes from common "household" type spills. While the technology is a bit different from this description, this is a simple explanation of the theory involved.
      
      
      • Inherent Soil and Stain Treatments:
      
      
      • Acid Dye Resistors: (applicable to nylon carpets only) Best described as large, colourless dye molecules that are applied during the dyeing process, filling dye sites and creating a negative charge on the fibre surface, that makes the fibre less susceptible to attachment of food dyes commonly found in artificially coloured foods and drinks.
      
      
      • Fluorocarbon Base Resistors: (applicable to all carpet fibre types) Fluorochemicals are most commonly added to carpet fibre after dyeing (except in some cases where the fluorochemical is integrated into the polymer prior to crimping and bulking the fibres). Fluorochemicals are used to reduce the surface energy of the fibres making it soil more slowly and making it less susceptible to possible staining materials.
      
      
      • Silicone Base Resistors: These are silicone compounds suspended in a solvent solution that have inherent capabilities to decrease the surface tension of a textile fibre, when topically applied. Because of lower costs, silicone based resistors are an alternate to fluorine based soiling retardants. Their big disadvantage is their lack of repellency against oil-based soiling. Some formulations have also been found to contribute to accelerated soiling in carpets and have therefore become in disrepute. As a result some carpet manufacturers have voided their warranty coverage if their carpets have been treated with silicone based formulations. Carpet end users (owners) should verify the use of silicone base resistors with the carpet manufacturer before having their carpet cleaned and topically treated with this product afterwards.
  • Static Control Protection: Static control is the ability of the carpet to dissipate shock. Static electricity is generated when two dissimilar surfaces such as shoe soles and carpet fibre rub together (foot traffic) to produce a static charge in low humidity conditions (less than 40%). The charge or build-up is dissipated when a grounding (e.g. hand to door knob contact) occurs. The control of static electricity build-up and discharge is critical where it may affect sensitive equipment such as computers, and hospital monitoring equipment, etc.
  
  
  • Note: In some environments where electronic components are being assembled or where sensitive mainframe computers are used, static control much lower than 3.5 kV may be required. Generally these areas will also necessitate the use of other static-control measures, such as humidity control, special shoes, wrist straps, and antistatic smocks. In such cases the carpet mill representative must be contacted for recommendations and details.
    
    There are a number of methods used to inhibit or minimize the build-up of static electricity in synthetic carpet before it reaches the threshold of human sensitivity (approximately 3.0 kilovolts (kv). The two most commonly used ones are:
    
    
    • Topical static control treatment: this process uses a topical spray applied after carpet production. This chemical treatment is not permanent as it can be worn off with foot traffic, removed by successive cleaning, and/or it can be masked by residues left by cleaning. In addition the topical treatment contributes to carpet surface soiling in the long term.
    
    
    • Inherent static control: this process adds a carbon composite nylon filament into the bundle of yarn (and backing material in the case of cut pile carpet) that conducts or dissipates static charges generated by foot traffic. This process is used by most if not all major brand nylon producers and lasts the life of the carpet. Olefin fibre is inherently static-resistant, as it is similar to the surface of most shoe soles (only dissimilar surfaces rub to create a static charge). Other inherent methods include the use of fibre blends and metallic fibres, the addition of a moisture absorbing (humectant) treatment to fibre mix, or the incorporation of conductive lattices and backings.
    
    Test Method: The propensity of a carpet to dissipate static build-up after hot water extraction cleaning can be measured by testing in accordance with AATCC 134 based on controlled conditions of 20% relative humidity and a set temperature of 21°C (70°F) with the results stated in kilovolts. A maximum static generation rating of less than 1.5 kv is recommended for sensitive areas (computer rooms, etc.).
    
    
    • Anti-Microbial Protection: Carpets may be exposed to food or other deposits on the surface, which in the presence of moisture provide a medium on which bacteria, fungi, yeast, mould, and mildew can grow. This is a concern when carpet is used in hospitals, nursing homes, restaurants, schools, and health clubs. In other applications, such as residential, and with normal cleaning procedures, this may not be a concern. Be that as it may, anti-microbial protection, which inhibits the growth of many of these organisms, is available for most commercial carpets. It must be remembered however, that although these treatments, which are microbe-specific, inhibit and minimize the growth of these organisms, they do not eliminate them. There are two methods used to inhibit or minimize the growth of these organisms:
    
    
    • Topical treatment: this process uses a topical spray applied after carpet production. This chemical treatment is not permanent as it wears off with foot traffic, is removed by successive cleaning, and it can be masked by residues left by cleaning. In addition the topical treatment contributes toward carpet surface soiling in the long term.
    • Note: If topical sprays are applied to carpets after installation the manufacturers' warranties may be voided since such treatment are outside of their control and can be improperly applied.
      
      
      • Inherent treatment: this process introduces chemical additives at the fibre production stage so that the treatment or resistance becomes an inherent or an integral part of the carpet construction.
    
    
    • Moth-Proofing (for wool carpets): Most wool and wool-blend carpets are permanently moth-proofed by the manufacturer. Carpets containing wool that are not permanently moth-proofed must be kept clean. Synthetic fibres are not subject to moth damage.
    
    
    • Indoor Air Quality Rating: to minimum Canadian Carpet Institute and Carpet and Rug Institute (USA) Indoor Air Quality standards, with maximum 0.5 mg/m².hr total VOC emission in accordance with ASTM D5116. Refer to Part A09 – Environmental Issues.
    
    
    • Fire and Flammability Rating: Refer to Part A08A - Flammability Issues.

5 • PREPARATION MATERIALS

.01    Patching, Filling, and Levelling Compounds:  Refer to Part A13 - Patching and Filling for information and requirements.

6 • UNDERLAYMENTS FOR CARPET

.01    Panel Type Underlayments:  Refer to Part A10 - Acceptable Conditions for information and requirements.

7 • CARPET CUSHION

.01    Refer to Part C03D - Material Guide - Cushion for carpet cushion.

8 • CARPET ADHESIVES

.01    General:

• The term adhesive (sometimes referred to as cement) applies to the total line of bonding materials, sealers, seam welding agents used in the installation of carpet (and cushion), seaming tapes, hardware and trim.


• The type and application of adhesives shall be as recommended by both the material and adhesive manufacturer to suit the substrate type, the type of carpet, cushion, base, and accessory and the type of application required.


• Caution Note: The design authority / specification writer is cautioned against specifying a particular manufacturer or type of adhesive as each carpet and cushion manufacturer may have specific recommendations in regard to the type and usage of adhesives for their particular products and installations. The National Floor Covering Association (NFCA) therefore recommends that the Design Authority specify adhesives "as recommended by the flooring material manufacturer to suit installation requirements". The grade (standard or premium) and the type (based on VOC content as well as use of water resistant or water proof types) should however be noted where applicable.


• LEED Requirements: Where the flooring installation must conform to LEED requirements, the type of adhesives used throughout (i.e. for installation of underlayment panels, flooring, bases, and accessories) shall be governed by those requirements.


• Refer to Part A14 - Adhesives and Fastenings for general adhesive information.

.02    Adhesive Types: The following general descriptions of adhesives and their general uses are a guide only. The selection and use of any adhesive shall be done with great care          and in consultation with both the adhesive and carpet and cushion manufacturer.

• Multi-Purpose Adhesive: Specially designed for a wide range of glue-down installations. The following are typical adhesive variations to suit material and substrate differences.
  
  
  • Adhesive suitable for installing all carpet backings except polypropylene, urethane, and vinyl. Not recommended for outdoor use or below grade sub-floor differences.
  
  
  • Adhesive suitable for installing all carpet backings except polypropylene, urethane and vinyl. Recommended over most types of substrates, indoors or outdoors, at all grade levels provided that hydrostatic pressure, excessive moisture or alkali conditions are not present.
  
  
  • Adhesive suitable for installing all carpet backing except urethane and vinyl. Recommended over moist substrate types, indoors or outdoors, at all grade levels, provided that hydrostatic pressure, excessive moisture or alkali conditions are not present.


• Carpet Cushion or Pad Adhesive: Refer to Part C03D.


• Vinyl Back Carpet Adhesive: Type designed for installing vinyl-backed carpets over most types of substrates at all grade levels, where hydrostatic pressure, excessive moisture or alkali conditions are not present.


• Urethane Backed Carpet Adhesive: Type designed for installing urethane-backed and a wide range of other carpets, over most types of sub-floors indoors or outdoors, at all grade levels, provided that hydrostatic pressure, excessive moisture or alkali conditions are not present.


• Releasable Carpet Adhesive: Type designed for the installation of both broadloom carpets and modular or tile carpet where a later removal is considered. May have to be used in conjunction with a sealer over porous floors. Not recommended for some foam-backed or urethane foam-backed carpets. Suitable over all types of substrates including well-bonded resilient floors at all grade levels. This type of adhesive should attach more securely to the carpet backing than to the substrate, so that if the application has been done correctly it will come up with the carpet.


• Tackifier Adhesive: A factory applied permanent or release type coating applied to the reverse side of modular carpet complete with a removal film or covering for peel and stick application.


• Outdoor Carpet Adhesive: Water resistant type designed for permanent outdoor installation of outdoor carpet and synthetic turf. Not recommended for vinyl or urethane-backed carpets. Suitable over asphalt paving and concrete. Because of flammability, use outdoors only.


• Tackless Strip Adhesive: Type designed for bonding tackless carpet strips to a substrate where anchoring nails cannot be used (such as over radiant heated floors, self levelling underlayments, etc.). It may also be used in conjunction with mechanical fasteners as extra insurance against them loosening. This adhesive is usually a flammable, solvent rubber based contact cement type.


• Contact Adhesive: Type designed for installation of carpet edge mouldings to a substrate and also to adhere carpet to difficult or irregular surfaces.


• Carpet Seam Adhesive: Type designed for edge sealing cut carpet edges to inhibit unravelling, reinforce sewn seams, and for binding and repair work. There are two types:
  
  
  • Non-flammable, neoprene, rubber based adhesive: for seaming rubber, urethane, jute, and other synthetic backed carpets, in direct glue-down situations. Not recommended for vinyl backed carpets. (Acrylonitrile rubber base types are recommended for seaming vinyl backed carpets).
  
  
  • Non-flammable, latex based adhesive: for seaming jute backed carpets.


• Seam Sealer: Topical type of adhesive for welding carpet backing together along seams and joints of rubber type foam and sponge back carpet.


• Adhesive Solvent: Used for clean-up of spilled carpet seaming adhesive and for removing adhesive from tools and trowels.

.03    Application of Adhesives and Trowel Notch Sizes:

• The appropriate adhesive, trowel notch size, spread rate, and application technique shall be as recommended by carpet, cushion, and adhesive manufacturers.


• The trowel notch must be large enough to apply a continuous uniform film of adhesive to the substrate or cushion to ensure full coverage and a minimum of 85% transfer of the adhesive to the cushion or carpet backing.


• The texture of the carpet backing is an important consideration in the selection of the correct trowel notch size required for the proper adhesion of a carpet to a substrate or to a cushion. Woven and unitary-backed carpets require full penetration of the adhesive into the valleys or depressions between tuft rows as well.


• The cushion or carpet is then installed over the adhesive and rolled with an appropriate roller to ensure full contact of the adhesive.

9 • CARPET ACCESSORIES

.01    Tackless Strips: This installation "device" developed in the 1930's revolutionized carpet installation by providing an easier and a more economical method of securing the                  carpet to the floor. Prior to this, carpet was either loose laid ("floated") on the floor or was turned and tucked under and then fastened to the floor using upholstery tacks. The              word "tackless strip" is the preferred term but it may also be referred to as carpet strip, tack strip, or tackless carpet gripper.

         Tackless strips are typically made using solid wood or minimum three-ply plywood (with stronger five-ply plywood also available). Aluminum tackless strips are also available              for use in areas where wood may not be suitable, in high traffic areas such as entryways where constant traffic may be detrimental to the pins, and for low pile carpets.

         There are a number of important factors to consider when selecting tackless strips for a particular installation. These include the type (including backing) and thickness of                  carpet to be secured, the width, height or thickness, as well as the length of the strip, the number of pin rows and height of the pins, the type of strip to be used (wood or                  aluminum), and the method of securing the strip to the substrate surface.

• Tackless Strips Types: Strips are manufactured to suit various requirements:
  • Pre-nailed (Wood): for wood and composition floors.
  • Pre-nailed (Concrete): for concrete floors.
  • Standard: for use with automatic nailers or where anchoring nails can not be used.
  • Special (Regular): 21 mm (7/8") wide wood strip with 2-rows of pins.
  • Special (Extra Wide): 25 mm (1") wide wood strip with 2-rows of pins that has more holding power than Regular tackless strips.
  • Special (Commercial Jr.): 30 mm (1 1/4") wide wood strip with 3-rows of pins. An economical alternative to double stripping and full width Commercial carpet strips. This type is good for Berber carpet.
  • Special (Commercial): 45 mm (1 3/4") wide wood strip with 3-rows pins used for long stretches where greater holding strength is required.
  • Special (Spacers): 1220 mm (48") lengths 3 mm (1/8") thick plywood, used to eliminate height differences between tackless strip and underlayments thicker than 10 mm (3/8") or height difference between carpet and adjacent flooring.


• Tackless Strip Pin Heights: These vary to suit the application requirements and are classified by the following Pin Types:
  • Type C: Pin protrusion 6 mm (1/4") used for carpet with rough or thick backings.
  • Type D: Pin protrusion 5 mm (3/16") used for carpets with short, dense pile to avoid pins showing through carpet face.
  • Type E: Pin protrusions 5.56 mm (7/32") used for the average carpet installation.
  • Type J: Pin protrusion 3.9 mm (5/32") used with very thin carpet, fine velours, and velvets with thin backings.
  • Aluminum: Pin protrusion 3 mm (1/8") 240 pins per 1220 mm (48") length, 25 mm (1") wide. Used for very thin carpet to avoid pins from showing through face yarn.
• Tackless strips may be adhered to substrate surfaces using adhesive when required or by mechanical fasteners such as staples or anchoring nails of types to suit the thickness of the strip as well as the type of substrate (wood or concrete) and the density or hardness of the substrate (where extra strength nails may be required).

.02    Gripper and Binder Bars: Other methods of attaching carpet may be required where tackless strips are not suitable or sufficient. The following fastening devices are                      available:

• Gripper Edge Binder Bars: An invisible clamp-down carpet bar used in combination with tackless strip at fireplace hearth, closet doorways and other low traffic areas.
• Door Metal: (Pin and Pin-less) used where carpet meets hard surface floor covering.
• Combination Bars: consisting of metal moulding with flange and tackless carpet strip.
• Binder Bars: Used for bridging between carpet and hard surface or carpets at different levels.
• Special Purpose Binder Bars: Multi-purpose, using regular or pin-less aluminum and vinyl edge or vinyl T-cap inserts.

.03    Reducer and Transition Strips: purpose made in a variety of sizes, colours and materials (e.g., vinyl, aluminum, etc.) to provide a finished termination trim or a sloping trim to          cover the difference in adjacent flooring materials thicknesses (one of which being the carpet). These strips may be mechanically attached to the substrate using nails or                  screws or be adhered to the substrate by using an appropriate adhesive and may be used with both stretch-in and glued down carpet installations. Local carpet and flooring              accessory suppliers should be consulted for types and details.

.04    Other Accessories:

• Stair nosings: vinyl, rubber, wood and metal.
• Thread: used for seaming and minor repairs.
• Pin tape: used for seaming, low traffic areas.
• Padding tape: used to join seams of pad to prevent movement of pad.
• Double face tape: used for area carpets on hard surfaces, to prevent shifting of carpet.
• Fasteners: Staples, nails and tacks
• Hot melt seaming tape: used in seaming of carpets, comes in two widths.
• Latex: used for reinforcing on repairs and as a seam sealer.

10 • CARPET BASES

.01    Refer to Part B03C - Material Guide for additional information on resilient rubber and vinyl bases for carpet.

.02    Types: A variety of bases may be used with carpet. These include the following:

• Cove or Toe Base: This is a base with a sloped extension or toe at the bottom of 16 mm (5/8") for standard cove base or 25 mm (1") for extended toe base offered by some manufacturers.


• Straight or Toe-Less Base: Identical in all aspects to cove base except that the coved-toe has been removed.
• Caution: Straight or toe-less base may be used in conjunction with carpet only if it is installed tight to wall faces. Because of the small area at the foot of the base, which provides only a minimum coverage of the carpet, this type of base should not be used where there is a gap between the flooring and wall face.
  
  
  • Tapered / Carpet Base: Wedge tapered base for carpet with 6 mm (1/4") notch with spacer used in lieu of toe-less or toe base. This type of base is installed before carpet installation and the carpe tucked into the notch. Heights offered are 84 mm (3 5/16") and 106 mm (4 3/16").
  • Caution: Consult base manufacturer and local distributor for product availability.
    
    
    • Profiled or Millwork Base: This is a specialty rubber base with a profile similar to moulded wood base board and available in various thicknesses and heights that is offered by a limited number of manufacturers. Bases are available in a variety of colours and the material may also be painted in accordance with manufacturers recommendations. Consult base manufacturer and local distributor for product availability.
    
    .03    Dimensions: Consult base manufacturer and local distributor for product gauges, widths, and availability for base material (rubber or vinyl) and types noted above. Common          sizes (unless otherwise noted) are as follows:
    
    
    • Heights: Typical heights are 63.5 mm (2 1/2"), 102 mm (4"), and 150 mm (6"). In addition, 75 mm (3"), 89 mm (3 1/2"), 114 mm (4 1/2"), and 125 mm (5") may also be available – verify with manufacturer.
    
    
    • Thicknesses: (uniform end to end) 3 mm (1/8") with 2 mm (0.080") available for vinyl base only.
    
    
    • Lengths: 915 mm (36"), 1220 mm (48"), or coils of 3660 mm (144") for all heights and 3050 mm (100") for 152 mm (6@) base. Most common use is coils / continuous lengths.
    
    .04    Caution: The type (toe-less, standard or extended toe, self-cove, vent cove, or profiled), height, and colour of base must be specified and clearly indicated on Finish                          Schedules because of the wide range of prices. If no material, type, or colour has been specified, it will be assumed to be either a black vinyl standard or toe-less base                      (depending on type of flooring, e.g. toe-less base for carpet).
    
    

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