A wine cask that holds approximately, two butts, or 252 U.S. gallons. Back Ullage - Also known as headspace, the unfilled space in a wine bottle, barrel, or tank. Unoaked - Also known as unwooded, refers to wines that have been matured without contact with wood/oak such as in aging barrels.
The tun is an old English unit of wine cask volume, holding about 954 litres, almost a cubic metre. Etymologically it is identical to the ton, a unit of mass or weight. Originally, it was a genuine unit of volume and measured 256 gallons (28), which is the base for the name of the quarter of 64 corn gallons.
A mash tun is a vessel in which malt and warm water are heated; a lauter tun is a vessel with a perforated bottom that allows the wort to drain. The spent grain left behind is sometimes used as animal feed.