Why do all distilleries have copper stills?
Star of the show and pride of place, the rich gleam of copper is ubiquitous in distilleries. But why are stills made of copper?
Whenever we visit a distillery, the one place we stop at the longest (apart from perhaps the tasting bar) is in front of the beautiful copper still.
Fermentation tanks, bottling lines, intricate science labs, they’re fine. But it’s the striking colour and fascinating shape of the still that draws us in.
We know instinctively that this is where the magic happens, the business end of the distillery.
But why do distillers prefer copper for their still?
There are a number of reasons that copper is considered the best option for distilling, and not just because it looks pretty.
Copper is a unique metal whose properties do remarkable things in the distilling process.
For a start, copper distributes heat incredibly evenly. Fewer hot spots mean a more uniform boil of the base spirit, so the evaporation process is easier to control and the outcome is consistent.
Surprisingly, copper also has antibacterial properties and can eradicate certain fungi and bacteria. It’s why water pipes are usually made of copper.
But the most important element (pun intended) of copper is how it interacts with the compounds in the alcohol itself.
As the alcohol heats up, unwanted impurities—in particular sulphites—combine with hydrogen ions to create hydrogen sulphide, which smells like rotten eggs. It’s also quite a dangerous product, being highly flammable and toxic.
Obviously, we don’t want that in our gins, rums and whiskies.
But as this compound comes into contact with the surface of the still, it reacts with the copper, becoming copper sulphate, which drops out of the vapour and stays inside the still.
The downside to this process is that small amounts of copper in the still are sacrificed in each distillation and over time, distilleries will have to replace their stills, but that sacrifice is worth it.
Aside from the magic of chemical reactions like these that ‘clean up’ the spirit, many believe spirit made in copper stills has a superior flavour and texture, and the majority of distilleries you visit, you’ll find a beautiful copper still at their heart.
So next time you visit a distillery and you find yourself admiring the big belly of a pot still, the long snaking swan neck of an alembic still or the tall portholed towers of a column still, remember it’s not just good to look at from the outside.
It’s beautiful on the inside too!