So is it only whisky that doesn't keep aging, or are all spirits the same?
All Spirits, once bottled, are as old as they will get. It is the time they spend maturing in the cask that the age refers to.
There are many different ways that the final taste can be affected during the maturing stage though, from type of cask used (new or old barrels, French or American oak).
If they are old barrels, the previous contents will affect taste (bourbon, sherry, port, red/white wine etc).
The size of the barrel plays a big part as well, as the great the contact with the wood (eg 1/2 cask or 1/4 cask).
Some fortified wines will get better with more time spent in a barrel (eg port) but make sure it is a wooden not metal one (these are just decorative). Some people will also put other spirits into them, but results are hard to be consistent with. (Personally, I am happy to play with 10 litres of port, but the cost of 10 litres of S.M. To try improve the taste is out of my budget).
There is so much to discuss in regards to this one aspect of liquor I could go on for hours.
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