How on earth do they manage to extract whiskey that is already absorbed in the barrel staves?
Do they pulverise the staves then press the powdered results to get the last drop of useful liquid out? Surely someone must know.
Now that I don't know for sure. Any answer that I give would just be a guess.
They could use a huge press and squeeze out the liquid. When enough pressure is applied, the liquid will definitely come out. But as I said, it's just a guess.