The flavour imparted by a wooden cask is just as integral to a whisky’s profile as the barley and water. Patrick Tillard visits Speyside Cooperage to learn more.
Photographer / ALEX MITCHELL
In the verdant forests of Missouri, straight towering oaks stretch to the skies. On the floor, speckled sunlight breaks through the canopy, highlighting an abundance of new arboreal activity – a reminder that these trees started life as an acorn some 100 years earlier. Willie Taylor, the director of Speyside Cooperage, where over 100,000 whisky casks are made and repaired every year, inspects a number of trunks, selecting only the finest to be felled and extracted. Just as it was in 1947, when his family started the business, these visits are of major importance – this wood, once cut, quartered, aired and dried over the course of 18 months, is shipped to Scotland and will go on to influence and flavour a large measure of the country’s revered nectar.
Back on home soil, on the edge of Craigellachie in the heart of Speyside’s rolling hills, the Missourian white oak goes under the hands of a skilled team preserving the ancient art of coopering. This is the largest working cooperage in the UK, combining the same methods and hand tools used by distant ancestors with modern machinery to speed up and perfect the process.
The use of wooden casks dates back to the earliest civilisations, when they were used to store and transport community commodities. And while metals and plastics have long superseded most wooden containers, when it comes to the maturing of wines and spirits there is nothing to surpass these primitive vessels.
Distilleries form their unique tastes and notes through the distilling process of barley, yeast and water, however, the flavour imparted by the wooden cask is just as integral to the end result. Once filled, the spirit draws out the natural oils of wood (vanillins) over the period of maturation, adding character to the whisky’s profile.
The coopering process itself is as intriguing to watch as the casks are central to the whisky industry. From the moment the cask takes its shape with the aligning of staves to the moment the final metal hoops are hammered into place, every step is meticulous and well practiced, the team exhibiting a similar finesse to that of a gun engraver, shoemaker or tailor – each an art of craftsmanship in its own right. It is an art that requires years of experience and ability.
The assembly of the concave staves is a tricky job, yet made to look as easy as falling off a log by the coopers on the workshop floor. As if completing a puzzle aimed at those between the ages of three and six, the cooper slots each stave into place, creating a seamless watertight fit.
Metal hoops are then tightened around the cylinder, before it is steamed for an hour, softening the wood sufficiently to enable it to bend. This allows for the open end to be drawn in and secured, forming the barrel-shape.
From here on, the process enters the phases that will see it influence the whisky it will later hold. The cask is toasted around an open fire for 40 minutes, firstly to set the wood, and secondly to open up the grain pores on the inside. This caramelises the wood and releases wonderful spicy, vanilla flavours that will be evident in the end product – be it a 10- or 21-year-old bottle.
The casks destined for whisky rather than wine then go through an additional charring process, in which the inside is allowed to burn for up to 30 seconds depending on whether the distillers have specified medium or heavy charring.
Lids are then shaped, fitted and sealed; the bung hole is cut; and a hydraulic press tightens the metal hoops one last time – it all flows incredibly smoothly and efficiently. Air and water are injected to ensure that each cask is as watertight as a ship’s hull, and then the process is complete.
The only remaining step is to dispatch the casks to various distilleries across the country, where they will be filled with distinctive blends and malts and left to mature.
In addition to making casks from scratch, Speyside Cooperage undertakes a huge amount of repair and restoration work. By law, American casks used for bourbon can only be used once, so are shipped over to Scotland and re-used for Scotch whisky.
Structurally, a cask may have a lifespan of 50–60 years, but after it has been used for four or five maturing cycles it loses its flavour-enhancing properties. These casks are then de-charred, stripped and re-charred, giving them a new lease of life. Or, if past the point of no return, they are turned
See for yourself
Discover the ancient art of coopering yourself by visiting Speyside Cooperage – open all year, Monday to Friday.