For many people, the shiny metallic copper stills are one of the soul elements of whiskey. This is undoubtedly related to aesthetics, but why have whiskey distilleries insisted on using copper stills since ancient times? Why not keep up with the times and use more durable stainless steel or aluminum stills?
We must first ask if and why in a scientific and objective attitude. So are all stills made of copper?
The answer is no.
In the early days of whiskey making, various durable and malleable materials were used, such as ceramics and glass, due to material constraints.
But copper soon replaced them and became the ideal material. The reasons are simple: copper’s high malleability allows it to be easily shaped and molded into designed shapes; copper is quite efficient at transferring heat and is corrosion-resistant.
Nevertheless, the use of copper is indeed “old-fashioned” enough, and the cost of copper is not low either.
This has often reminded distillers to keep trying newer, cheaper, and more durable materials, such as stainless steel, which have been tested among American distillers.
However, early distillers who used stainless steel as a distiller discovered the ludicrous fact that stainless steel gave the original whiskey a sulfurous taste that was unpopular with consumers.
In contrast, the “safety” of copper in the taste of whiskey has been historically proven, and the distillers have demonstrated its previously unknown benefits through experiments.
Copper’s properties allow it to undergo chemical reactions in the walls of the stills to remove highly volatile sulfur compounds (mainly dimethyl disulfide, an odor-causing substance that makes whiskey smell bad), and it also aids in the formation of esters, which are an essential source of fruitiness in whiskey.
In continuous distillation, the copper material also helps concentrate unwanted compounds, improving the efficiency of distillation and making the whiskey taste smoother.
But do not think that the scope of copper is only distillers; condensers are also inseparable from copper—the mainstream worm tube condensers and shell and tube condensers have copper as a raw material.
So what’s the difference between insect tube condensers and shell and tube condensers?
Although they are both made of copper metal, due to the internal structure difference, the shell and tube condenser ultimately contact and react with the original whiskey more than the insect tube condenser, so the shell and tube condenser treated liquor has a light body and smooth and mature taste characteristics.
And accordingly, the insect tube condenser on the liquid has less “intervention”; the spirit has more sulfur smell, “meat” and fruit aroma, etc. And some manufacturers now try to use stainless steel condensers in pursuit of a more unique and bold whiskey taste.
Of course, it is not difficult to imagine that the loss is inevitable when the copper is in the condenser and many whiskey reactions.
Simply put, the copper becomes “thin.” At this point, one can only replace the corresponding parts, and this is also called by the distillers “copper sacrifice,” as the Scots call the evaporated wine in oak barrels “angel’s share.”
To sum up, although copper material is expensive, its excellent flexibility, thermal conductivity, and stability, recognized by history all make copper material become an integral part of the traditional whiskey-making process.
The golden whiskey is coming out of the golden glowing stills, and the amber color given by the oak barrels; the process is like a trinity, unimpressed by the outside world.