Commonly used material for the manufacture of stainless steel tanks used for fermentation, storage and ageing of wines. Stainless steel has a high content of chromium (as well as nickel, molybdenum and titanium). On the surface, the chromium forms a closed layer with the atmospheric oxygen (so-called passive layer), which protects the iron in the alloy from rust. The advantages over tanks made of wood and concrete are easy cleaning, especially of tartar, optimal use of space, flexible volumes (from small tanks of 50 litres up to a million litres), complete sealing against oxygen, low shrinkage and better possibility of temperature control. Disadvantages are higher purchase costs and slower maturation of the wines. For wine ageing in wooden barrels, see barrique age ing and barrel age ing. For complete lists of containers, see barrel types and wine vessels.