“Portugal produces about half the world output of commercial cork, and its exports over recent years have accounted for around 70 percent of world trade.”
The precious and versatile vegetable tissue known as cork is the outer bark of the cork oak tree (Quercus suber or as the Portuguese call it sobreiro). Cork (cortiça) is most easily stripped off the tree in late spring and summer when the cells are turgid and fragile and tear without being damaged. The tree quickly forms new layers of cork and restores its protective barrier. No tree is cut down. This simple fact makes cork harvesting exceptionally sustainable, leading to a unique balance between people and nature.
Cork has a structure that you can compare with that from a honeycomb. Every cm2 consists of approximately 40 million cells. These cells, as well as the spaces in between, are filled with a kind of gas resembling air, without CO2. Thus the cork cells work as small sound and heat insulators and absorb pressure and shocks. This is what makes cork so remarkable. Up till today there has not been found any other material which combines the same characteristics as cork does.
Given the advent of synthetic cork, is there a future for cork wine stoppers?
… For long aging however, the only closure with an adequately long track record is natural cork. So to be safe, that is the closure to choose. Once we have solid long-term evaluations of synthetics and screw caps, it will be possible to judge their suitability for extended aging, such as more than ten years.
Over centuries, winemakers have consistently taken advantage of new technology to improve their product, from oak barrels to bottles to modern crushing and pressing equipment and micro-oxygenation. While manufactured closures have some key advantages, it is proving difficult to displace natural cork due to its centuries-old tradition, albeit with a few problems, and its connection to the natural environment.