Have you ever wondered where corks come from? I got to wondering about it one day, and decided to look it up. It’s pretty fascinating. Here’s what I found out. Corks come from the bark of a particular type of Oak Tree, called Quercus Suber. They only grow in Southwest Europe and Northwest Africa. Cork is actually used in many more products than just wine bottle closures, such as flooring, musical (woodwind) instruments, thermal insulation, bulletin boards, shoes, baseball cores, spacecraft heat shields, and more. In 2007, Portugal issued the world’s first postage stamp made of cork!
Cork has many unique physical properties that make it such a good ingredient with which to build other products. Cork has a honeycomb structure, where each cell is separate and filled with air. This makes cork elastic, which makes it ideal for stoppering up glass bottles. Cork is naturally fire-resistant, waterproof, and light-weight. Cork is a poor conductor of heat and vibration, which makes it ideal for flooring and sound-proofing.
There are almost 8,500 square miles of cork forest worldwide. 34% of is in Portugal, and 27% in Spain. When it comes to annual production, Portugal supplies 49.6% of the cork used to create various products, 30.5% from Spain, and the rest divided up between Morocco, Algeria, Tunisia, Italy and France. The cork industry is regarded as environmentally friendly because cork trees are not cut down to harvest the cork, trees continue to live and grow. The sustainability of production, and easy recycling of cork by-products are two of its most distinctive aspects. Plus, the industry employs around 30,000 people worldwide. And interestingly enough, even though wine-bottle corks only account for 15% of cork production by weight, it accounts for 65% of the value!
Cork trees are harvested for the first time at about 25 years old; they live about 300 years. After the first time, they are harvested every 9 to 12 years (it depends on the country). Harvesting the cork, called extracting, is done from early May to late August. The extractors are highly skilled at removing the bark into ‘planks’, and are very careful not to damage the tree. See the picture slideshow below.
Then the cork planks are stacked and dried (usually on concrete, to lower the risk of contamination). After drying, the cork planks are boiled to soften, clean and flatten them. Next the planks are sorted and graded, and cut into workable pieces. The best, and thicker pieces will be used for punching wine-bottle corks from, either by hand (for high-end corks) or machine-punched. The rest are ground up to make technical cork (varied uses), also called agglomerate cork. No waste in this highly sustainable product!
Now back to corks for wine bottles. Glass bottles that we are so used to today have only been around for about 400 years, despite the fact that we’ve been drinking wine for 8,000 years. Originally, oil-soaked rags stuffed in the tops of whatever the wine was in, was the stopper. Once wine started to move from place to place however, something needed to be developed so wine couldn’t spill out, and oxygen and airborne bacteria couldn’t get in. Aha! Use of the cork stopper in glass bottles became routine.
Natural cork closures are used for about 80% of the 20 Billion bottles of wine produced each year. Alternative wine closures such as plastic or synthetic stoppers or aluminum screw caps have advantages and disadvantages. However, a study conducted by PricewaterhouseCoopers in 2005 concluded that cork is the most environmentally responsible stopper over the alternatives. Long Live the cork! Or should I say, Long Live the Quercus Suber!
photo credit of man extracting cork: By Cazalla Montijano, Juan Carlos – Instituto Andaluz del Patrimonio Histórico, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=26270324