Understanding Whisky Casks and Maturation

What the cask does

“its common for whisky to be finished in Ex-Bourbon or Sherry Casks, giving it a nice sweetness or caramel vanilla flavors.” — Beginners Guide to Whisk(e)y (story, 2017)

“Our wood program runs a wide spectrum from the new American oak casks (of which we have two types of char/toast levels), to ex-Bourbon casks, ex-Westland casks that we’re re-using, Quercus garryana casks” — Westland Distillery sets high standards for American Whiskey – Interview with Master Distiller Matt Hofmann (interview, 2017)

“And ultimately it’s the quality of the wood that determines the quality of the whisky, so we are hugely picky about our casks.” — Wolfburn Distillery – Shane Fraser – the brains behind the Scotch (interview, 2017)

“First, the Scots are aging exclusively in used barrels.” — Stephen Paul of Hamilton Distillers tells us about Mesquite Smoked Whiskey from Tucson, AZ (interview, 2017)

“We use a variety of ex-bourbon barrels, as well as virgin oak and some ex-sherry barrels” — Two Brewers Yukon Single Malt Whisky Interview (interview, 2017)

“Remember that anywhere from 60 to 80% of the flavor in a whiskey comes from the maturation process.” — Tom Lix changing the way Whiskey is Made, Cleveland Whiskey (interview, 2017)

Sherry, port and other casks

“Sherry cask maturation has a long history in single malt whiskey production, so it was important for us to continue this element of tradition in our whiskey.” — Westland Distillery sets high standards for American Whiskey – Interview with Master Distiller Matt Hofmann (interview, 2017)

“The Laphroaig PX Cask is made with whisky matured in three types of cask – American oak casks, Quarter casks and the titular Pedro Ximénez casks.” — Laphroaig PX Cask – Review (review, 2017)

“We have Fino, Manzanilla, Oloroso, and Pedro Himennes Sherry casks, Congnac casks, and a variety of other unusual casks being used for primary aging.” — Copperworks Distilling Interview – The American Single Malt (interview, 2017)

“Our flag ship product is our Teeling Small Batch which we would mature malt & grain whiskey in ex-bourbon barrels prior to blending them together and then allowing them to marry in rum barrels.” — Teeling Whiskey – the Pride of the Irish (interview, 2017)

Finishing and full maturation

“Finishing (also known as double matured or wood- finished ) is the procedure that some whiskeys undergo whereby the spirit is matured in a cask of a particular origin and then spends time in a cask of different origin” — Springbank 17 Sherry Wood Tasting Notes (story, 2017)

“This 17 year old single malt Scotch whisky has been 100% matured in Sherry oak casks and bottled at cask strength.” — Springbank 17 Sherry Wood Tasting Notes (story, 2017)

“So rather than just relying on finishing, we’re able to produce whisky that’s fully matured in special casks.” — Wolfburn Distillery – Shane Fraser – the brains behind the Scotch (interview, 2017)

Char

“The lower level of char allows more flavor from our distillate to push though over the years in the barrel.” — Deerhammer Distilling – Making Whiskey, Drinking Whiskey (interview, 2017)

“A good bit less caramel, vanilla, flavor than you get in a #3 or #4 char, and a bit more coffee, raisin, dark chocolate flavor that comes though from our grain bill.” — Deerhammer Distilling – Making Whiskey, Drinking Whiskey (interview, 2017)

“An alligator char is an industry term relating to charring the inside of a barrel long enough so that it cracks and burns into what appears like rough alligator skin.” — Is whisky better when its made in Japan? (interview, 2018)

“This deep char will give the whisky a subtle smoky flavor and a darker richer color.” — Is whisky better when its made in Japan? (interview, 2018)

Size, climate and the warehouse

“All of our maturation and warehousing happens in a rackhouse located in the temperate and humid climate on the coast of the state.” — Westland Distillery sets high standards for American Whiskey – Interview with Master Distiller Matt Hofmann (interview, 2017)

“As you probably know, whiskey matures more quickly in smaller barrels because of the higher ratio of wood surface to contents.” — Stephen Paul of Hamilton Distillers tells us about Mesquite Smoked Whiskey from Tucson, AZ (interview, 2017)

“Heat is another factor that accelerates maturation, and here in Baja Arizona we are hot and dry.” — Stephen Paul of Hamilton Distillers tells us about Mesquite Smoked Whiskey from Tucson, AZ (interview, 2017)

“…it’s maturing at three or four times at the speed at which it matures in Scotland.” — Paul John Single Malts – India’s world-class whisky (interview, 2017)

“Definitely, that’s the plus side of it, but on the negative side, we have a huge evaporation loss.” — Paul John Single Malts – India’s world-class whisky (interview, 2017)

“Here in Iowa, we lose about 18% to the angel’s share in the first two years, versus more like 12-14% with the big producers.” — Cedar Ridge Winery & Distillery – From farm to Shelf Whiskey (interview, 2017)

“Our rick houses are free of temperature and humidity controls, causing us to lose more to evaporation than most whiskey producers.” — Cedar Ridge Winery & Distillery – From farm to Shelf Whiskey (interview, 2017)

“BB: I believe that our maturation is hugely affected by humidity.” — Two Brewers Yukon Single Malt Whisky Interview (interview, 2017)

“Several barrels from both lots basked in the sun, highlighting the effects of maturation along an external wall.” — Bourbon Review – Old Forester Birthday Bourbon 2017 (review, 2019)

“93 barrels matured together on the 4th floor of G warehouse, yielding an extremely spice forward expression.” — Bourbon Review – Old Forester Birthday Bourbon 2017 (review, 2019)

Cask strength

“Cask Strength means that the alcohol has not been watered down to the standard abv between 40-45%.” — Beginners Guide to Whisk(e)y (story, 2017)

Oak species and cask sizes