I have an old 5L oak barrel that has been used in the past for aging rum. It hasn't been used in a long time so I am I the process of swelling the wood again by adding boiling water but when the barrel overflowed there was a wax like substance coming out.

Does anyone know what this is?

Second question, is boiling water enough to clean the barrel?

I am going to use I for flavoring cider.

2 Answers 2


Is it possible the barrel was previously lined with pitch? If so you might consider not using it. Pitch seals the wood and blocks the wood character from effectively aging the beer, as well as reducing porosity that contributes subtle oxidation and the development of microorganisms (all are primary reasons for barrel aging). Plus who want chunks of unknown sealant material in their beer?

If it's just residue from previous contents (such as beerstone/winestone) or organic buildup, a thorough scrubbing with hot water and food-safe cleaners should suffice.


I got 2 unused oak barrels from a South African. He had them for 25 years & never used them. He said before I use them, to clean them twice with boiling water to remove the wax sealant inside... Looks like parafin wax.

I filled them to the top, left them for 5 minutes and emptied them, twice each. A fair bit of wax floated on top of the water. One barrel was leaking so I put it in a sink overnight with water up to the top of the barrel inside and out. No leaks in the morning! Full of Muscat & Tokay now. With a decent glass of brandy in each to get the chemistry working...

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