Commonly used material for the production of stainless steel tanks used for the 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 oxygen in the air (so-called passive layer), which protects the iron in the alloy from rust. The advantages compared to tanks made of wood and concrete are easy cleaning especially of tartar, optimal use of space, flexible volumes (from small tanks with 50 litres up to one million litres), complete closure against oxygen, low shrinkage and better possibility of temperature control. Disadvantages are higher purchase costs and slower maturation of the wines. Concerning wine maturing in wooden barrels, see under barrique maturing and barrel maturing. For a complete list of containers see under Barrel types and wine containers.