What is cork made of? Cork consists of suberin cells in the shape of tiny pentagonal or hexagonal honeycombs, a complex fatty acid and filled with an air-like gas, which makes up 90% of its volume. It possesses an average density of around 200 kg/m3 and low thermal conductivity.

Let's get the obvious out of the way first. Wine corks are an effective wine seal made from cork bark and have been pretty much the standard in stoppering wine bottles for over 300 years. They stop air getting into the wine and spoiling it (though tiny amounts of air may still sneak through).

The going rate is about 10 cents per cork. You can try to charge more if you have some type of rare cork you think is worth it, but if you just want to move your merchandise, price accordingly.

Screw caps do not pose the same risks of developing cork taint as natural cork, but they also don't let oxygen in, which is why they're typically found on wines intended to be drunk young, such as many whites and fruity reds.