Copper is so important to spirits production that it almost qualifies as an ingredient. However, a copper still doesn't automatically make a spirit good. It's how copper is used in the process that makes the difference.
Copper is an essential ingredient in every spirit
On every distillery tour, the gleaming copper still is the headline feature, but stills aren’t made of copper because it looks so good. Copper interacts chemically with the spirit as it’s being distilled, scrubbing sulphurs out of the fermented liquid and vapour. You can’t make good spirits without copper, it’s essential.
The most energy inefficient device in the world
Copper is also popular because it transfers heat well in the boiler, but that same characteristic means a copper still is haemorrhaging heat into the surrounding air, requiring huge amounts of energy to keep the still contents boiling. A typical still room is downright tropical in temperature. That’s energy, which didn’t need to be used, leaking out of that gorgeous copper still in every direction.
The best way to remove bad flavours is not to make any
Sulphur smells and tastes bad, even a tiny bit will ruin a spirit. During fermentation, yeasts produce loads of different compounds alongside the alcohol, some of these being sulphurs. Yeast produce more sulphur when stressed, either by fermenting too quickly or at too high a temperature. Many distilleries ferment quickly, (sometimes in as little as three days) to increase overall production throughput, knowing their giant copper still will scrub away most of the errant flavours.
I start by working with Hobsons Brewery to keep the yeast very happy and comfortable during fermentation. They ferment my spirit wash for a full seven days, carefully controlling the temperature to never exceed 21 degrees, thus eliminating most sulphur simply by never creating it in the first place. This allows me to use heavily insulated stainless steel for my still rather than traditional copper energy monsters. One of my mottos is: Happy yeast loves stainless, unhappy yeast begs for copper.
I do use a bit of copper, but in a special reaction chamber in my still column to eliminate any tiny remnants of sulphurous compounds from the spirit, and I carefully clean the copper between each batch. The result is strikingly clean spirit produced with much less energy. I use traditional methods but will never shy away from thoughtful innovations like these.