production
Mash tun
No legal definition
The vessel in which grist is mixed with hot water so malt enzymes convert starch into fermentable sugars, and from which the sugary wort is drained off.
Not a legal term
No whisky regulation in Scotland, Ireland, the United States, the EU or Japan defines this. It is a trade or marketing term, so it is only actionable if its use is actively misleading.
Often confused with washback
Mashing — sugar extraction, hot, no yeast — happens in the mash tun. Fermentation, with yeast and cool, happens afterwards in the washback.
Worth knowing
Distilling mash tuns aim for clear wort and maximum extract, unlike brewing. A typical Scotch mash uses three or four waters, the last held back as the first water of the next mash.
Related terms
Last reviewed 2026-07-30 · All glossary terms