Just posted an illustrated guide to how cork is made, on the main wineanorak site – here. It’s a very attractive substance. Such a shame about the existence of cork taint, and also the fact that cork isn’t totally consistent. But when it’s good, it can help wines age magnificently.
In neck closures – natural cork, technical cork, synthetic cork – share one property. They have a special dynamic of oxygen transmission. For the first few months after bottling, oxygen dissolved in the body of the closure is released. After this, oxygen transmission proceeds at a uniform rate. This could be important in the way that the wine develops, and is difficult to replicate with a crown cap or screw cap liner.