On a learning curve

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08 January 2010
On a learning curve
By Mike Wilkinson

“A short dumpy still, even on the spirit side, will have a maximum alcohol concentration that you can deliver. A tall one will have a slightly higher in-safe strength and will also allow you, on the spirit side, to distill on quite a bit further without bringing in the ‘feinty’ aromas. A tall spirit still would let you run on spirit for considerably longer than a short one would.”

The variations within the industry are huge. Glenmorangie’s stills, for example, are the tallest in Scotland, at almost 17ft. They date back to William Matheson’s decision to buy second-hand gin stills instead of the traditional onion-shaped whisky pots. The company says the height of the stills helps to banish harsh flavours before maturation. The Macallan’s spirit stills, on the other hand, have short necks, which lead to a heavier final product.

“The Glenmorangie stills are an extreme version of what you can do to deliver very high quality on the spirit side,” says Harry.

“But basically, the bigger the still, the less relative copper area is available to the spirit vapour. That means if you go for huge stills – an example would be Jura distillery – then you have to be very careful in distillation because you probably have to operate at a slower rate of distillation or you don’t get enough copper contact in the wash distillation in particular.

“The smaller the still, the more copper surface area you have available to the vapour, and to a certain extent smaller stills can be run a bit harder to deliver top quality spirit than you can run a big still.”

Although they can come in any variety of shapes and sizes, the one element common to every still is its material – copper.

“It’s a major part of the process,” says Harry. “The copper has a very important role to play in removing undesirable organosulphur compounds during the wash distillation.”

Richard Forsyth recalls one distillery’s chief engineer who thought he could dispense with copper, in favour of stainless steel – with disastrous consequences.

“He put stainless steel bottoms onto the stills, and stainless steel condensers in,” he says. “But when it came to produce the whisky, it wouldn’t clear because the unwanted sulphates weren’t coming out. The following year we had to change all the stainless steel back into copper.”

Richard says there’s even an element of superstition among distillers about not tampering with such an integral part of their whisky-making process.

The fastest-wearing parts are the wash necks and spirit pots, which last between 10 and 12 years, while wash pots and spirit necks can be used for between 25 and 30 years. When it’s time to replace them, as well as making precise measurements for its blueprints, Forsyths will take a set-wire mould to make sure the replacement is as similar as possible.

“The distillers are extremely sensitive to any change,” he says.

Harry agrees that tampering with the shape of the still could change the character of the finished product.

“Every distillery has its own distinctive fingerprint. It’s in the interest of distillers to have continuity for their brand, so if they need to replace a part of the distillation system, they’ll try to replace it with the same part as they had before.”

By the same token, Richard makes no guarantee that a certain size or shape of still will produce a certain style of whisky.

“We make a point, especially to new markets in Asia for example, that we can’t guarantee a certain type of spirit out of a certain type of pot – that’s part of the whisky industry’s mystique.”