When it became more difficult to source sherry casks during the Spanish civil war in the late 1930s, use of bourbon casks became much more common. Nowadays, somewhere between 300 and 400 thousand bourbon barrels are shipped to Scotland for second use, compared to somewhere around 18,000 sherry casks.
A little over 90% of the 8.5 million casks in Diageo’s inventory in Scotland are ex-bourbon or rye American Oak. At Bruichladdich, their figure is closer to 97%.
The stability of bourbon production in the U.S. means that second-use American oak is sure to remain a prime choice for Scotch distillers, regardless of whether they keep the barrel or turn it into a “hoggie.”