F03A2 - MATERIAL GUIDES - HISTORY OF CORK
Preface:
This study guide provides a brief and simple overview of the history of "cork" as a floor covering material.
THE HISTORY (AND MANY USES OF) OF CORK
Cork is the outer bark of an evergreen oak of the genus and species Quercus Suber (oak cork). This tree is concentrated around the Mediterranean in southwest Europe (primarily on the Iberian Peninsula - Spain and Portugal) and in northwest Africa where soil, temperature, rainfall, and wind conditions are ideal for its growth. For millions of years, the cork oak has survived on its inherent strength and spontaneous natural regeneration. This tree forms a rugged bark that over time grows to a considerable thickness and acts as a protective shell against harsh climate changes and numerous fires that affect the region.
The bark from this tree has been used by mankind since ancient times in a variety of ways such as cork stoppers, buoys, and sandals and has been found in archaeological sites dating as far back as ancient Egypt. Ancient Greeks and Romans utilized cork in many new ways, including in construction, for insulation, and for nautical uses such as floats and even for personal flotation devices. As well, early Portuguese and Spanish explorers used cork as an integral material in the construction of their ships and other seagoing equipment because of its unique insulation and floatation properties.
In gathering cork bark it was the ancient Greeks who first discovered that stripping the bark from the tree produced a new, higher quality cork. Harvesting cork bark has not changed from these early times. The outer bark from the oak's trunk and major branches is still carefully stripped by hand by experienced cork strippers who use a specialized cork axe to slit the outer bark and peel it away from the tree. No mechanical stripping devices are allowed. The first stripping of bark (with the material known as virgin or male cork) occurs when the trees are a minimum of 15 to 20 years of age, with subsequent stripping done at 9 to 10 year intervals thereafter. Most countries can only (by law) strip bark when the tree is dormant in the winter months between December through March. The trees regenerate this outer layer 12 or 13 times during their 150 to 250 year lifetime. The harvested cork bark is then removed from the forests and left out in the open air for six months. This weathering process improves the cork's quality. The bark is then sorted by quality and size.
The primary or first use of the harvested cork bark is for the extraction of cork stoppers to meet the demands of the world's wine and champagne industries. This amounts to over 13 billion cork stoppers annually. The remaining cork (called "blocker waste) is then ground up and processed for use in the production of agglomerated cork and cork and rubber compounds (a process developed in the late 19th century). These materials are used in a variety of applications from floatation devices, gaskets, bulletin boards, and most importantly in the fabrication of flooring materials. This agglomeration process has greatly expanded the applications of cork, and as a result cork usage expanded even more.
With increasing demands for cork, its production became an industry, eventually resulting in vast forests of cork oak trees dedicated to providing cork bark. Such forests were and still are carefully cultivated today with European forests accounting for two-thirds of cork production with the remaining one-third from North Africa. The total land surface occupied by cork oak forests today is 2.2 million hectares (5.434 million acres) of which 56% is in Portugal and Spain. The cork industry now employs more than 15,000 workers in factories devoted to converting raw cork and cork by-products into commercial products. In addition, the industry employs thousands of seasonal workers during cork harvesting and for the maintenance of the oak forests.
Because of its value and usage oak cork tree forests are carefully monitored and cultivated and with careful management practices this renewable resource has resulted in a steady supply of cork, with future supplies well assured. In fact, in the prime cork-growing region of Portugal, cork oaks and harvesting their bark is protected by law in order to protect this valuable resource and ensure the quality of the harvest.
Today cork is still found in applications as diverse as building materials to toys, bulletin boards to wallpaper, gaskets to insulation, decorations to duck decoys, and most commonly as wine corks. Because of its resilience cork is also used in construction as a floor covering material in tile and plank form, as a flooring underlayment, and as a joint-filler. No other material recovers from compression or puncture as cork. In the United States the sale of cork and cork products exceeds $150 million annually of which cork stoppers (i.e. wine corks) amounts to $110 million, while the sale of agglomerated cork flooring, (also known as cork composition flooring, and other cork products amounts to approximately $40 million.
Cork flooring has been used around the world and in North America for over a century and has been used in commercial environments for many years. In Canada, for example, the old Toronto Stock Exchange building had cork floors that eased the joints of traders who were on their feet all day and providing a quieter indoor atmosphere than would traditional hard tile surfaces. In the 1950's, cork was frequently installed in restaurants, gymnasiums, and offices - anywhere where people spent a lot of time standing. Prestigious buildings in the United States where cork flooring has been used include:
Cork tiles installed at this time were considered "massive" tiles. These were solid cork with the same pattern all the way through that could be refinished just like hardwood floors (sanded down and then varnished). This type of tile was extremely durable and was usually 4 to 6 mm (3/16" to 1/4") thick. As time went by, cork tile manufacturers endeavored to reduce costs by replacing these thick "massive" tiles with a veneer pattern on the surface of a composition cork base and by decreasing the thickness of the tile to 2 mm (-1/8"). In addition, flooring adhesives used for cork tile changed from a toxic, but extremely strong mastic to a more modern flexible urethane. These changes sometimes produced undesirable effects such as tiles breaking apart during installation and/or lifting after installation. As a result the cork flooring industry's reputation suffered and sales of cork tiles declined.
Like most flooring types, cork flooring's popularity has had its ups and downs. Over the past decade floating floor technology has been successfully adapted to cork flooring to produce yet another variety of cork flooring available. This, along with environmental concerns and cork's eco-friendly nature, the need for better indoor air quality and overall comfort, and the demand for "natural" or "green" products has resulted in a resurgence of cork flooring with architects and designers enthusiastic once again about the distinctive look of cork flooring. Perhaps another reason for this renewed interest may be that cork flooring is quiet, warm, comfortable, and relatively easy to maintain, while still remaining reasonably priced.
This study guide provides a brief and simple overview of the history of "cork" as a floor covering material.
THE HISTORY (AND MANY USES OF) OF CORK
Cork is the outer bark of an evergreen oak of the genus and species Quercus Suber (oak cork). This tree is concentrated around the Mediterranean in southwest Europe (primarily on the Iberian Peninsula - Spain and Portugal) and in northwest Africa where soil, temperature, rainfall, and wind conditions are ideal for its growth. For millions of years, the cork oak has survived on its inherent strength and spontaneous natural regeneration. This tree forms a rugged bark that over time grows to a considerable thickness and acts as a protective shell against harsh climate changes and numerous fires that affect the region.
The bark from this tree has been used by mankind since ancient times in a variety of ways such as cork stoppers, buoys, and sandals and has been found in archaeological sites dating as far back as ancient Egypt. Ancient Greeks and Romans utilized cork in many new ways, including in construction, for insulation, and for nautical uses such as floats and even for personal flotation devices. As well, early Portuguese and Spanish explorers used cork as an integral material in the construction of their ships and other seagoing equipment because of its unique insulation and floatation properties.
In gathering cork bark it was the ancient Greeks who first discovered that stripping the bark from the tree produced a new, higher quality cork. Harvesting cork bark has not changed from these early times. The outer bark from the oak's trunk and major branches is still carefully stripped by hand by experienced cork strippers who use a specialized cork axe to slit the outer bark and peel it away from the tree. No mechanical stripping devices are allowed. The first stripping of bark (with the material known as virgin or male cork) occurs when the trees are a minimum of 15 to 20 years of age, with subsequent stripping done at 9 to 10 year intervals thereafter. Most countries can only (by law) strip bark when the tree is dormant in the winter months between December through March. The trees regenerate this outer layer 12 or 13 times during their 150 to 250 year lifetime. The harvested cork bark is then removed from the forests and left out in the open air for six months. This weathering process improves the cork's quality. The bark is then sorted by quality and size.
The primary or first use of the harvested cork bark is for the extraction of cork stoppers to meet the demands of the world's wine and champagne industries. This amounts to over 13 billion cork stoppers annually. The remaining cork (called "blocker waste) is then ground up and processed for use in the production of agglomerated cork and cork and rubber compounds (a process developed in the late 19th century). These materials are used in a variety of applications from floatation devices, gaskets, bulletin boards, and most importantly in the fabrication of flooring materials. This agglomeration process has greatly expanded the applications of cork, and as a result cork usage expanded even more.
With increasing demands for cork, its production became an industry, eventually resulting in vast forests of cork oak trees dedicated to providing cork bark. Such forests were and still are carefully cultivated today with European forests accounting for two-thirds of cork production with the remaining one-third from North Africa. The total land surface occupied by cork oak forests today is 2.2 million hectares (5.434 million acres) of which 56% is in Portugal and Spain. The cork industry now employs more than 15,000 workers in factories devoted to converting raw cork and cork by-products into commercial products. In addition, the industry employs thousands of seasonal workers during cork harvesting and for the maintenance of the oak forests.
Because of its value and usage oak cork tree forests are carefully monitored and cultivated and with careful management practices this renewable resource has resulted in a steady supply of cork, with future supplies well assured. In fact, in the prime cork-growing region of Portugal, cork oaks and harvesting their bark is protected by law in order to protect this valuable resource and ensure the quality of the harvest.
Today cork is still found in applications as diverse as building materials to toys, bulletin boards to wallpaper, gaskets to insulation, decorations to duck decoys, and most commonly as wine corks. Because of its resilience cork is also used in construction as a floor covering material in tile and plank form, as a flooring underlayment, and as a joint-filler. No other material recovers from compression or puncture as cork. In the United States the sale of cork and cork products exceeds $150 million annually of which cork stoppers (i.e. wine corks) amounts to $110 million, while the sale of agglomerated cork flooring, (also known as cork composition flooring, and other cork products amounts to approximately $40 million.
Cork flooring has been used around the world and in North America for over a century and has been used in commercial environments for many years. In Canada, for example, the old Toronto Stock Exchange building had cork floors that eased the joints of traders who were on their feet all day and providing a quieter indoor atmosphere than would traditional hard tile surfaces. In the 1950's, cork was frequently installed in restaurants, gymnasiums, and offices - anywhere where people spent a lot of time standing. Prestigious buildings in the United States where cork flooring has been used include:
- The First Congregational Church in Chicago, Illinois - Installed in 1890.
- The Mayo Clinic and Plummer Building in Rochester, Minnesota - Installed in original building in 1912 and then in 1940 added additional flooring for a total 300, 000 sq. ft. of flooring.
- Falling Water residence in Ohiopyle, Pennsylvania designed by architect Frank Lloyd Wright in 1937.
Cork tiles installed at this time were considered "massive" tiles. These were solid cork with the same pattern all the way through that could be refinished just like hardwood floors (sanded down and then varnished). This type of tile was extremely durable and was usually 4 to 6 mm (3/16" to 1/4") thick. As time went by, cork tile manufacturers endeavored to reduce costs by replacing these thick "massive" tiles with a veneer pattern on the surface of a composition cork base and by decreasing the thickness of the tile to 2 mm (-1/8"). In addition, flooring adhesives used for cork tile changed from a toxic, but extremely strong mastic to a more modern flexible urethane. These changes sometimes produced undesirable effects such as tiles breaking apart during installation and/or lifting after installation. As a result the cork flooring industry's reputation suffered and sales of cork tiles declined.
Like most flooring types, cork flooring's popularity has had its ups and downs. Over the past decade floating floor technology has been successfully adapted to cork flooring to produce yet another variety of cork flooring available. This, along with environmental concerns and cork's eco-friendly nature, the need for better indoor air quality and overall comfort, and the demand for "natural" or "green" products has resulted in a resurgence of cork flooring with architects and designers enthusiastic once again about the distinctive look of cork flooring. Perhaps another reason for this renewed interest may be that cork flooring is quiet, warm, comfortable, and relatively easy to maintain, while still remaining reasonably priced.