Technically, stills can be made of many materials including aluminum, iron, brass, stainless steel or copper. Most are copper or stainless steel. Depending on who you ask, the short answer to the question, “Why are stills made of copper?” is taste.
Copper is the preferred material in the construction of a still to impart flavor into the distilled spirits. According to Broadslab Distillery, both stainless steel and copper are excellent conductors of heat: dispersing the heat evenly across the entire surface of the metal and creating a more even distillation. But where both stainless steel and copper will not put harmful chemicals into your final product, copper has the advantage over stainless in that whisky out of a copper still simply tastes better. When distilling in copper, the copper reacts on a molecular level with the sulfurs put out by the fermenting yeast. It “cancels-out” the sulfur taste which would otherwise be bitter and not as smooth.
In the process of distilling, the sulfur coming from the yeast binds itself to the copper, making hydrogen-sulfide which in turn, forms copper sulfate. The copper sulfate sticks to the inside of the still after distillation is completed. After a thorough cleaning of the copper still, the copper sulfate is washed down the drain, and not into your whisky… unlike other stills made from different metals.
The World’s Largest Copper Pot Still
The largest pot still in the world is the “Jameson Still Cork” in the Midleton Distillery constructed in 1825 located in County Cork, Ireland. It had a capacity of 37,971.65 U.S. gallons and is no longer in use. Photo courtesy of Stephan Schulz.