Natural Cork

Harvesting cork. (Image by marylandcork.com)

Harvesting cork from the tree. (Image by marylandcork.com)

Ah, the small squeak of the stopper against glass as you open a bottle of good wine, what could be more pleasing? Perhaps the subtle-spring in your heels as you walk across flooring from recycled wine stoppers? Or the dampened, acoustic softness that seems to seal out the noisy bustle of the world beyond? Yes, cork is a material that does it all, and does it well: it’s natural (derived from an evergreen oak, Quercus suber), beautiful, and regenerates quickly. Best of all, this wonder material is making a comeback.

The spectrum of such qualities in one material naturally led to its industrial utilization, which dates back to classical times. Romans used it to seal amphora, in shoes, fishing floats and even as insulation for their beehives. In the 1st century A.D. the Roman naturalist Pliny the Elder made extensive reference to cork oaks in his work on Natural History, explaining that in Greece the trees were adored as symbols of liberty and honor, for which reason only priests were allowed to cut them down. Cork oaks were consecrated to the god Jupiter, and their leaves and branches were used to crown victorious athletes. It wasn’t until the 15th and 16th centuries, however, with the widespread use of the glass bottle, that cork was used as a popular stopper, opening up immense prospects for the sale and shipping of beverages.

Cork book from 1909.

A guide to cork, published 1909.

In modern times, cork has been used in a variety of manufacturing processes. Highly flexible and having excellent “memory”, the automobile industry has employed it in transmission belts, tires, and gaskets. During the Second World War, it proved durable enough for use in military equipment and was used by the Navy for its incredible buoyancy and resistance to rot. It also worked well as an insulator of refrigerators.

Sorting cork at the Armstrong Factory, 1909.

Female workers sorting cork at the Armstrong Factory in Pittsburgh, Pennsylvania, 1909.

The design world was also a beneficiary of this incredible material. It was first used in the United States around 1890 and became popular when architect Frank Lloyd Wright chose cork flooring for many of his home designs. Cork flooring was used in the First Congressional Church in Chicago and the old Toronto Stock Exchange. In the 1950s, an American company produced the first agglomerated cork tiles.

Musicians and recording engineers applauded its superior ability to absorb ambient noise in recording studios and vibrations in musical instruments. More recently, cork has come into vogue yet again for its durability and good looks. (Need that subtle spring in your step? Cork flooring is recommended for those who stand for long hours, suffer from back pain, or just want something warmer to walk on than hard wood.) More recently, designers have been experimenting with cork as a material for furniture and even clothing. The list of uses of this amazing material goes on and on.

1950s Cork Floor in 'Better Homes & Gardens.' (Image found on American Vintage Home @ Flickr)

Cork floor as seen in ‘Better Homes & Gardens,’ circa 1950s. (Image found on American Vintage Home @ Flickr)

These days, Portugal accounts for 50% of the world’s cork harvest, followed by Spain, France, Morocco, Algeria, and Tunisia. Harvesters in Portugal and other countries have taken careful steps to insure the viability of their cash crop, making it illegal in many areas to cut down the majestic tree. (In fact, Portugal was the first to enact agrarian laws in 1209, protecting the tree.) So valuable are these trees to the economy of the Mediterranean countries that they are supervised carefully for the first three decades of their lives.

After 25 to 30 years, the mature cork tree reaches a size large enough for use. This initial growth period allows the cellular structure within the tree to mature so that there are textural consistencies. Harvesting is pleasantly archaic: it involves hand stripping the outer bark of mature oaks, leaving each tree to regenerate for the next nine to ten years. Trees have an average lifespan of 150 years, some even reaching well over 200, making them incredibly productive.

Cork stopper from a wine bottle.

Cork stopper for a wine bottle.

The tree has a thick, insulating bark that likely evolved as a protection against forest fires. As a raw material, cork consists mainly of tiny 14-sided honeycomb-shaped cells filled with air and encapsulated by a fiber called lignin. This cellular structure gives cork products tremendous thermal and acoustic properties, as the air pockets act to insulate heat and sound. As well, natural cork is hypoallergenic; the presence of suberin (a naturally occurring substance) resists the growth of mold, mildew, and bacteria, making it an excellent flooring choice for people with persistent allergies.

Natural stands of cork oak can support diverse ecosystems and aid in the survival of certain  endangered animals. For example, cork forests in the Atlas Mountains of Morocco and Algeria are home to the Barbary Macaque, (Macaca sylvanus) and Barbary Red Deer (Cervus elaphus), and cork-spotted scrubland in Southern Spain offers refuge for the Iberian Lynx (Lynx pardinus). Because cork trees are spared from logging, they may aid in the survival of these animals. The loyal service to both animal and humankind is what may ultimately guarantee the longevity of the great tree. All in all, cork is perhaps one of the most useful natural materials in the market today and will most undoubtedly see a rise in popularity as we find new applications for it.

Cork floating device from 1909.

Early cork lifesaver vest from 1909.

The images of the Armstrong Cork Co. and floating device are from the 1909 book “Cork – Its Origin & Uses” found at Google Books.

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