Some bourbon enthusiasts may wonder: why do bourbon focused distillers only use a barrel once? After all, other distilleries and brewers use second and sometimes third-fill casks, sometimes even those same ex-bourbon casks. So why not bourbon?

Over the years, a number of factors have led to this practice, from tradition and early shipping practices, to chemistry and law.

Buffalo Trace barrels with whiskey awaiting their day. (image via Buffalo Trace)

In the early days of bourbon making, Kentucky distillers would package their whiskey in large oak casks to be shipped down the Mississippi River or to the East Coast.…