Glaser’s enquiring mind has led him to question accepted wisdom on wood choices and maturation practices, and he incurred the disapproval of the Scotch Whisky Association (SWA) back in 2005 when he launched a ‘vatted malt’ by the name of The Spice Tree.
For The Spice Tree Glaser took a number of malt whiskies that had been conventionally matured for around 10 years in a mix of first-fill and refill American oak casks and subjected them to a unique secondary maturation process in casks fitted with flat staves of heavily-toasted new French oak.
However, the SWA deemed this practice, routinely used by winemakers, not to be ‘traditional’ in terms of Scotch whisky, leading Glaser to withdraw his product in 2006, while remaining convinced of its quality and integrity.
John Glaser is not a man to give up easily on an idea he believes in, and in 2009 a second generation of The Spice Tree appeared, using the same component malts and cask mix, but this time transferred for secondary maturation into ‘custom’ casks, described by Glaser as “American oak barrels with French oak heads.”
This practice did not contravene the SWA’s interpretation of ‘traditional,’ to the relief of the many fans of the original The Spice Tree, and Compass Box also now utilises French oak cask heads in the maturation of some component spirit for its Great King Street blended Scotch whiskies and for The Spice Tree’s companion blended malt Oak Cross.
So just what is it about French oak that finds such favour with John Glaser? “For us it’s not French oak per se, it’s about using a higher quality of oak in the making of Scotch whisky,” he insists.
“When we started up a dozen years or so ago, the idea of sourcing better quality wood, with more inherent complexity, was far less common than it is now.
“In general, the Scotch whisky industry uses lower quality and less active oak than winemakers. They have really been into oak flavours for far longer. The vast majority of casks used for Scotch whisky maturation are ex-Bourbon casks, and the quality of oak used for Bourbon is far inferior to that for wine. You can visit a cooperage producing Bourbon casks and wine casks, and the area where they are making barrels for wine is far more craftsmen-like.
“We like to use French oak because we can extract flavours and complexity of flavour from it that we don’t get from American oak. American oak is higher in vanillins than European oak, and once charred you get more lactins, which give Bourbon its coconut character. Instead of that, from our French oak we get complex spices, cloves, cinnamon and dried fruits. French oak is not superior to American oak, it’s just different. I like the profile our supplier can produce and I like the fact that it’s quite close by, just in mainland Europe.”
The supplier in question is a saw mill in the Vosges Forest of eastern France, which provides Compass Box with sessile oak. “We buy their finest grain, highest-quality 24-month air-seasoned oak,” says Glaser, “We purchase cask heads with several different toast levels, and heat treatments are where you can really create the flavour profile. There are two variables: temperature and duration. This is really wine barrel technology rather than whisky barrel technology – that’s what we are buying into.
“The guy doing the toasting monitors the process by computer. He knows the toast level profile the customer wants and there’s a temperature and time chart on his monitor; an ideal curve for each level, and sensors on the barrel. He adjusts heat levels and times to achieve the desired effect.
“It’s like roasting a coffee bean or a piece of meat, creating different sets of flavours. There are lots of variables such as a long toast on high heat or a short toast on low heat. One will give a profile of heavy vanilla when used for Scotch whisky maturation; another will offer heavy toasting flavours, while a third will give cloves and baking spices.”
Noting that he now just purchases cask heads from the saw mill, Glaser points out: “We have experimented with using whole barrels, but the effect is to totally dominate distillery character.”
Explaining the precise process that is used to create The Spice Tree, Glaser says: “We take the vatted malt which is around 10 years old; Clynelish, plus Teaninich and Dailuaine. Some we fill back into the original casks after vatting the malts and some we fill into our ‘custom’ casks – American oak barrel with French oak heads, and we will use three or four different toasting level permutations. After six months, or 36 months, we have variations on a theme. We blend it back with the spirit not filled into the custom casks to give us the end product.
“You could use toasted American oak heads on the casks, of course, but you wouldn’t get these complex spices.”
And what of the future?
“Spice Tree is a statement whisky for us. It shows what you can get from heavily-toasted French oak,” states Glaser. “We certainly intend to do more with French oak in future, and there will definitely be new projects in collaboration with the same Vosges Forest mill.”