Copper and Whisky, an Inseparable Partnership

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If you have never wondered how that beautiful amber nectar in the bottom of your whisky glass came to be then this probably isn’t the article for you. But if you are still reading then I take it you are a truly cultivated individual for whom the wonders of life still hold some fascination. You may logically ask why would you be reading about the creation of whisky on a metals blog? Well the answer is because without certain metals, whisky as we know it would not exist and wouldn’t that be a sad state of affairs?

The road to a sample of “the water of life is a long one and who better to tell it than one of Scotland’s oldest, The Macallan. The journey starts in the barley fields of Scotland. In other parts of the world, spirits are distilled from all kinds of crops but barley is uniquely qualified to the climate of Scotland because the tough outer husk protects the barley grain inside from the cool wet weather. During the first stage of whisky making the barley is encouraged to start the process of germination by immersion in warm water. This initial Malting stage involves breakdown of the cell walls to release the carbohydrates for subsequent conversion into sugars and hence alcohol. Taking up to a week, the germination is finally halted by drying in kilns and then the malted barley is crushed to form “grist comprising 20% husks, 70% soluble “grits that contain the carbohydrate and 10% “flour. The barley grist is then transferred into a Mash Tun with hot water to extract the carbohydrate in the form of starch along with other soluble materials that add to the unique flavor. This mashing eventually provides a sugar solution called Ëœwort’ which goes forward to fermentation.

Wort is converted with the help of yeast into a low alcohol wash as the yeast attacks the sugars and converts them to alcohol. The pace of this process is dependent on the temperature and time the components are allowed to be together and the quality of the yeast used. Imagine the time and experimentation required back in the 1500 and 1600’s to get this process right. Today this stage of the process is carried out in stainless steel vats the first of our metal references in case you were wondering.

This wash fermentation stage can take up to a couple of days and when complete the low alcohol typically about 8% – wort is sent for distillation in copper stills. Why copper? Only Copper Stills are ever used in making Premium Scotch and Bourbon Whiskies. Copper plays an essential role in Scotch Whisky making, it adds character and sweetens the distillate whereas stainless steel distillates are often flat and insipid.

Image courtesy of the Whisky Ambassador.

Furthermore, copper also removes sulfur compounds present in the wash from the grains that would otherwise pass over to the distillate. It may be for making lesser spirits other metals will do but for Whisky only the king of metals will suffice. These wash stills are directly heated and the alcohol vaporizes and is then condensed to a strength of about 21-23% alcohol by volume. The condensate is then heated again in spirit stills and the spirit condensed out is at some 71% but only a small portion is selected for long term storage. This “cream of the distillation process is colorless and constitutes typically less than 20% of the spirit distilled off. The rest is added to fresh wash and recycled again.

This small quantity of pure spirit is then transferred to oak casts. The wood is either American or Spanish Oak and is only used twice first timers or refills. The oak is seasoned, Spanish oak with Sherry and American with, you guessed it, Bourbon well you knew Bourbon was good for something right? This 71% spirit is then blended with spring water to 69.8% alcohol by volume and then stored for up to 50 years. In the famous Macallan distillery samples from up to 200 casks are assessed and blended by the Whisky Maker to produce a single malt of the most consistent quality. The final mix is then blended with more spring water to drop the alcohol content to 46% in a vat and then returned to casks to marry with the spring water for three months before finally being diluted with de-mineralized water to bottling strength before being bottled.

After so much work and so much loss of product along the way it is hardly surprising a good single malt whisky costs what it does. Next time you sample a drop of the amber liquid spare a thought for the long journey from barley grist to glass, and how the product would not be as special if it were not for those copper stills.

–Stuart Burns

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