Where does cork come from?
Cork is the bark of a Cork Oak. If you live in the States, you’re most likely familiar with a Beach or Chestnut tree which are both in the same family as a cork oak. The main difference between the cork oak and the chestnut and beach tree are three-fold. First, the bark of cork oak is significantly thicker and more resilient than those of other trees. Second, cork oak is native to the western Mediterranean basin, in countries such as: North Africa (Algeria, Tunisia and Morocco), southern France, Spain, Italy and Portugal. Third, a cork tree can grow in some of the most inhospitable and barren land you can possible imagine.
I am intimately familiar with the last point, because my legs are still recovering from our walk into the cork oak fields two weeks after our trip. Somehow missing out on the memo to wear pants, I dressed in shorts with open sandals to keep relatively cool fearing another 40 degree Celsius day. And although my plan worked in theory, continually able to feel the light cool breeze upon the back of my neck and legs, I deeply regretted my lack of girl-scout training which would have accounted for such needs. While Carlos de Jesus, Amorim’s Director of Marketing and Communications, and Ryan walked briskly to where we saw workers dotted across the orchard on ladders stripping and hauling cork, I meandered behind trying to strategically avoid the dry pointy scrub brush from scraping my bare legs.
Yet, it is trait, among many, that makes cork oak so incredible. Few trees have the capacity to adapt to soils virtually incapable of supporting any other economically viable crop. Moreover, cork oaks create an ecological balance by preventing further degradation to this barren microclimate. They are sturdy, stocky, resilient trees that make few demands on either humans or the environment.
Cork trees flourish in areas with little rain or nutrition. They grow in sandy chalk-free soils with low levels of nitrogen and high levels of potassium. The climate never falls below -5 degrees Celsius, nor may there be much rainfall (between 600-800 millimeters per year), leaving us with very few areas like Portugal where it has thrived for millions of years. There are more than 725,000 hectares of cork forest in Portugal alone, equivalent to 30% of the world cork oak population. And as a result of the way cork is harvested — shaved off the sides of trees in much the same way a sheep is shorn — means forests continue to thrive in areas where other economically viable crops cannot.
Yet, harvesting cork oak is not an easy task. This is not a vocation where you get merely take your inner aggression out on a poor tree. This is undeniably an art. It takes both intelligence and finesse to know both where you will cut and how deep to send the blade. If you cut too deep, you will damage the inner bark, causing irreparable damage or even death to the tree; but if done well, the bark will slough off easily with minimal trauma leaving only that beautiful burnt orange color of the inner bark. The color is not the result of someone painting the inner bark once the cork is harvested, but rather the tannins becoming oxidized once the inner bark is exposed. Therefore, it is of no surprise that cork harvesters need to be extremely skilled so as to both strip the cork in one solid piece, but also to to protect the life of the tree. Harvested in only the spring and summer these farming communities work quickly and efficiency to ensure both their livelihoods and that of the cork trees.
While we would all like to place full trust in an individual and a community to ensure the future of these trees, it is also helpful to have support of both the local and federal government as well. The Portuguese government has taken several precautions to protect the cork oaks by strictly enforcing a law that forbids any cork oak to be cut down or the bark stripped more than every 9 years. Therefore, in a tree’s lifespan of 150 to 200 years, bark can be stripped between 8 to 15 times! I’ll be the first to admit that I didn’t have a clue. I knew the bark can regenerate, but I had no idea the amount times it could potentially be harvested, nor did I know that it isn’t until the tree reaches approximately 27 years until the first harvest called, Virgin cork (or ‘male’ cork) can be taken. While industrial products can be made from the first three harvests, it isn’t until the tree is approximately 54 years of age until the first wine closures can be made from the bark.
Carlos actually showed us a cork oak he recently planted near the cork factory. A young, delicate tree with only a few shoots, it is so hard to imagine that it won’t be for another 5 decades before he will see a cork closure from his own little tree. It sort of makes Ryan and I a bit curious as to whether our rooftop terrace should have a little cork oak of its own.
What makes cork so fascinating to me is not just the way it is harvested, but the properties of cork itself. Unlike other bark, cork has a unique ability to withstand heat, vibration and sound. This why you will see cork used to soundproof music studios, as an insulator for rockets and as a way to lesson vibration in electrical appliances.
In 2003, when the forest fires raged through Portugal, the waxy interior of the cork bark called suberin, protected it from burning in the fire. And because cork is so light and buoyant, I can eventually make a little raft from my bazillion corks sitting idly in bags and float happily on the Mediterranean with a delicious glass of Portuguese wine! Plus, if I just can’t finish that bottle of wine, I can take a cork from my raft and as a result of its elasticity, I can close the bottle and save it for later! How’s that for versatile?!
Needless to say, we were very astounded and impressed by the process. The experience of watching each cut analyzed, realized, and finalized allowed us to be one step closer to understanding how the bottle of wine we’re drinking tonight contained a cork closure. In the next week, we’ll be bringing you the process from which these piles of bark are treated, cleaned, and finally, shaped into the stopper that we have all come to know.
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