Designation for by evaporation (Evaporation) resulting fluid loss in a wine container, especially in containers made of wood but also closed with natural corks bottles occurs. In the case of wood barrels, there is no absolute tightness compared to steel, glass or ceramic tanks, but in both directions (both outward and inward) there is a certain exchange of substances (liquid and also water) oxygen ). In old wooden barrels can be leaking especially between the staves a relatively high shrinkage result. The resulting whitespace depending on the type of wine in a barrel, especially at Jungwein regularly filled be to one oxidation to prevent. An influence also has the tightness of the spigot or the position of the bunghole on the barrel (see also under bung ). water and alcohol escape to varying degrees through the wood pores. With water molecules this happens faster, which however also from the humidity and air temperature is dependent.
High moisture content slows down the release of water but not alcohol, resulting in increased alcohol in relation to water loss. That usually means that in one wine cellar with ideally high humidity of 70% and more of the alcohol content reduced in the wine. In dry storage, on the other hand, the alcohol content increases. Internationally, especially in the spirits industry, the English term "ullage" for the evaporation loss of distillate used by the breathing wooden barrel. This is also poetically called " angels share ", Or in France as" part of the announced ". The French term "ouillage" is used both for the fading itself and for the process of refilling. The loss in a bottle, however, is in any case on a leaky or defective cork or closure due. This results in a lower filling level, See also below aging. bottle aging and maturity,