Characters of the cork

The cork is like a second skin of empty dead cells, made from bubbles of air containing old membranes and cells. This special constitution is responsible for the characteristics of this material : spongy, light and buoyant (no more 0.24 density to 1 of water), waterproof and insulating (thermal and acoustic), long lasting and almost non-decaying, compressible and elastic, resistant to fire, and resistant to wearing away in fragments, inactive (without smell or flavour).

This unique material seems to be specially made for stoppers. However, its properties were known a long time ago, and was used for fishing tackle, beehives, soles of shoes and amphora stoppers.