Term for the loss of liquid in a wine container due to evaporation (evaporation), which occurs mainly in containers made of wood but also in bottles sealed with natural corks. Wooden barrels are not absolutely leak-proof compared to tanks made of stainless steel, glass or ceramics, but there is a certain exchange of substances (liquid and also oxygen) in both directions (to the outside as well as to the inside). In old wooden barrels, leaks, especially between the barrel staves, can result in relatively high shrinkage. Depending on the type of wine, the resulting empty space in a barrel must be filled regularly, especially in the case of young wine, in order to prevent oxidation. The tightness of the bung or the position of the bunghole on the barrel also has an influence. Water and alcohol escape through the wood pores to different degrees. In the case of water molecules, this happens more quickly, but this also depends on the humidity, air pressure and air temperature.