It's a real irony. Copper receives a lot of attention, and credit for influencing the character of the new make spirit during distillation. But what about the coppersmiths, who are rarely mentioned, though without them nothing would happen.
Coppersmiths have a broad role which includes creating, installing, maintaining and replacing pot stills, condensers and spirit safes.
One distillery which has a coppersmith within the distillery team is The Balvenie, where Dennis McBain attained 50 years service as resident coppersmith in 2008, and he continues to provide support on a consultancy basis. Meanwhile, Diageo owns Abercrombie Coppersmiths, which has a history dating back to 1790 and employs 43 coppersmiths (who are responsible for Diageo's 28 malt whisky distilleries). Additionally, a specialist company such as Forsyths, which offers distilleries a full design, installation and maintenance service, has its own team of 15 coppersmiths.
"It's a specialised craft - you can't go into the local labour market and look for a coppersmith - you've got to train them from scratch. We take on three trainees a year, for a five year apprenticeship.
First and foremost candidates must show a willingness to learn, and be reasonably fit, as it's very physical work," says Richard Forsyth, chairman of Forsyths.
Charles King, Abercrombie's operations manager, adds, "We're looking for people who take great pride in what they do, and who like working with their hands. We've taken on two apprentice coppersmiths and engineers every year for at least 8 - 10 years."
The first year of an apprenticeship includes an engineering course at a Further Education College, acquiring the fundamentals of areas such as engineering, metallurgy and welding, as well as health and safety.
"The following few years are spent in the workshop, working alongside a trained coppersmith. Apprentices learn how to hammer and shape copper, and how to weld. They also learn how to make pot stills and condensers, working from technical drawings, and this includes cutting the required sections of copper on a water jet cutting machine," says Richard Forsyth.
Completing the apprenticeship is hardly the end of the process.
"It takes at least a further five years to properly learn the craft, working alongside an experienced coppersmith, with the vast majority of tasks being team based, for example replacing a complete pot still or sometimes just sections of the still in a distillery," says Charles King.
A coppersmith's year revolves around the annual 'silent season,' when distilleries cease production to carry out maintenance. As the silent season may only last several weeks, distilleries are continually monitored so that anything which needs replacing can be prepared in the workshop beforehand.
Monitoring the thickness of the copper in the pot stills is vital, as this decreases over the years, a consequence of the distillation process gradually 'eroding' the copper. Once the copper is below a certain thickness it needs to be replaced. Measurements are taken using an ultrasonic probe, which has been around for about 20 years. This replaced the traditional method of using a hammer and listening to the resulting sound. If it rang like a bell, everything was fine. If it produced a dull thud, it certainly wasn't.
"There's a lot of forward planning, at least a year ahead, and we usually start making all the different sections and stills in December ready to go into a distillery the following summer. We work closely with distilleries to plan the timing of the silent season," says Charles King.
Once the silent season begins it's a case of moving out of the workshop and into the distilleries.
"A pot still usually takes four men about six weeks to manufacture and replace, which includes two weeks work on site. We can send a smaller pot still already complete to the distillery, but if it's a larger pot still then, for ease of transportation, we send the pot (ie.base) separately, then weld on the head and the neck on-site," says Richard Forsyth.
Being a coppersmith requires enormous skill together with physical strength, but that doesn't necessarily limit the length of a career. It is now possible to extend the length of service.
"Health and safety regulations have extended the working life of a coppersmith, and the more experienced you are the more time you spend passing on this knowledge. One of our coppersmiths recently retired after 43 years service, at the age of 60," says Charles King.
The Merits of Copper
Copper is highly malleable and so complies readily with the shapes of pot stills (however idiosyncratic) stipulated by distilleries. Moreover, exemplary thermal conduction properties enable the stills to be heated quickly, saving energy.
Copper's influence on the character of the new make spirit includes a key factor, the ability to lower the level of sulphur compounds.
During distillation the charge (ie.alcoholic liquid) is heated and begins to vapourise. These vapours ascend the neck of the still on the way to the condenser, where they condense back into liquid alcohol. During this journey copper absorbs sulphur compounds from the vapours. Sulphur compounds include rubbery, meaty and vegetal notes, which are only present in tiny quantities, measured in parts per billion, but they are also very assertive and effectively 'mask' other characteristics. Consequently, lowering the level of sulphur compounds 'reveals' lighter notes.