Finishing is the procedure that some whiskies undergo where the spirit is matured in a cask of a particular origin and then spends time in a cask of different origin Typically, the first cask is an American oak cask formerly used to mature bourbon. The second cask may be one that has been used to mature some sort of fortified wine, often sherry, though sometimes casks for port, madeira, or even red burgundy or chardonnay are used.