Cork has for centuries been the spiritual partner to wine. Throughout the cork tree's long history of cultivation, the farmer's gentle prodding has enabled cork products to grow in quality and character. There are many facets of the cork industry, most people don't even realize that cork is the bark of trees that grow almost exclusively in one region of the world.

The supply of cork is limited but guaranteed. Cork trees occupy vast areas and are constantly reproducing. The areas occupied by cork trees are situated west of the Mediterranean basin and on the Atlantic coast many in Portugal, always close to vineyards. The cork tree needs a lot of light, relatively little rain, a degree of humidity, and thrives in altitudes up to 1,400 meters (above sea level).

The cork tree has a natural reproduction, by acorns or, more frequently, by producing shoots; however, these processes can be improved with extra care. Cork renews itself every 9 or 10 years over approximately 150 years. Like all trees, the cork oak bears sap wood formed from the bast (or inner bark) and the core. However, what sets it apart from other trees, particularly other oak trees, is its capacity to create a remarkable, complex fatty tissue (suberin) from its inner bark when it is separated from its protective covering.

The productive layers of the bast (inner bark), are called: cambium, the internal layer which grows towards the wood core of the tree; and phloem, the external layer which grows in the direction of the bark and produces cork.

In this way cork is formed at a rate of 1.5 mm per year, till a thickness of more than 60 mm is reached. This cork is called virgin cork and does not come away by itself; it is hard, and unsuitable for cork stoppers. On the other hand, it is used for the manufacture of bonding materials, because, after cork expansion by heat, the resin it contains becomes an excellent agglomerate.

When the trunk has reached a circumference of at least 0.80 meters, which corresponds to a virgin cork layer of 30 to 35 mm, the process of unmasking or peeling of the cork may take place. The expression "unmasking the virgin cork" is particularly appropriate since that part of the tree, which is revealed when the virgin cork is removed, is called the mother. The stripping, when well done, does not harm the trees, because the first layer of reproduction cork merges with the continuously developing virgin layer in the unpeeled part of the tree.

The area known as the ‘mother’ changes from a rose color to red ochre, then a reddish brown, and the following year to a grey, crust-like formation. From this the reproduction cork originates, at a rate of 1.5 mm to 4 mm per year. It is necessary to wait at least 9 years after stripping the virgin cork, before stripping again so as to get the first useful harvest, that is to say a thickness of around 2 to 5 cm.

The collection of the cork or the harvest, may be repeated every 9 years, and up to 12 or 15 harvests may be reaped. After this, the tree will no longer be acceptably productive.