I’m curious about the cleaning process of casks before a distillery transfers its whisky to mature/age. To use one of the popular names, just as an example, before Macallan transfers its whisky into a sherry [or bourbon or port or ale] cask, is the cask cleaned? If yes, by what method? Does it vary by distillery or country (à la, whiskey vs. whisky)? Is it all arbitrary or are there laws dictating cleaning process?

I’ve researched (online only) but wasn’t able to find any (sourced) information. Hoping there are experts here who can enlighten us.

3 Answers 3


Liquor casks are not cleaned between transfers, just emptied and stored until they need them again. The liquor that soaked into the wood makes sure nothing will grow in them.

Wine barrels on the other hand, need to be cleaned between transfers. Typically they are rinsed with hot water and then maybe steam. Left to drip dry for a day or two. Then sulfur dioxide is put into the barrel either through a gas or burning sulfur in the barrel. This sterilizes the barrel.

Many wine/sherry casks are reused as Whisky barrels. Minimal amount of cleaning is need before the strong alcohol is put in them (which sterilizes them).

  • Thank you very much for this. It’s as I assumed (unlike this answer who claims that it’s barely -if at all- cleaned) but am unable to corroborate it. As I inquired of a second answer to this q, do you know this from personal experience in the field or documented sources?
    – Oliver
    Commented Apr 5, 2019 at 13:50
  • If barrels are used only for spirits, they might never been cleaned or just rinsed with water, but the alcohol in the cask is at a stronger level than the final product, around 120 proof. That makes it a sterile environment. Wine barrels after they have been used are coated inside with all types of crud. Dead yeast, tartrate crystals, little pieces of grape skins. Stuff you don't want in your spirits, so they need to be thoroughly cleaned. I severely doubt they ship them with liquid in them. Wine barrels take months to dry out so if they are shipped quickly, they would be fine. Commented Apr 5, 2019 at 14:18

Usually, a cask is not cleaned before the spirit enters it, it's just emptied. With Wine casks (Sherry, Port, etc...) it is desired to get this flavour into the whisky, so cleaning would lessen this effect. Those already used casks are normally transported with some litres of wine still inside, so the cask would not dry out and break. Some distilleries even decide to keep the liquid inside when they fill it up with spirit, so they would even have a higher flavouring effect.

A kind of cleaning, that I know of, is used for the Jim Beam Devils Cut. They say it contains the "cut of the devil", which basically is the whisky, that is soaked inside of the barrel, after it was emptied. Jim Beam then fills the empty barrel with some water, which then "pulls" the devils cut out of the wood. This water is then later used to reduce the cask strength devils cut Whiskey to the strength of 45% and thus adding the devils cut.


This will vary greatly by product- bourbon for example requires “New “barrels other spirits might re use a sherry or wine barrel- scotch for example uses American whisky barrels. And so on. Typically barrels need to be either totally dry or totally full so cleaning will depend on if they are new or not. You can use steam to clean or rinse with water and so on. Chemicals or soap kind of things are rarely used as they can permeate and damage the wood.

  • 1
    Thank you for joining SE to answer my question but I’m afraid I don’t see how this answers my question(s). Unless your point is the last two sentences which is only helpful if you can provide sources.
    – Oliver
    Commented Mar 27, 2019 at 1:04

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