The distillation still

Before there is a still, there is fermentation. Yeast eats sugar from grain, agave, grapes or molasses and leaves behind a low-alcohol liquid. Whiskey makers call it a wash or a beer.

Alcohol boils at a lower temperature than water, around 173°F against water's 212°F. Heat the wash, and the alcohol and aroma rise first as vapor. Cool that vapor and it turns back into liquid, now much stronger.

That is all distillation is. The craft is in how you do it and which part you keep.

A pot still is the old way: a big kettle, usually copper, with a neck that carries vapor over to a condenser. It runs in batches. Fill it, heat it, collect the spirit, empty it, start again.

Pot stills leave more of the heavy, oily flavor in the spirit. Single malt Scotch has to be made in pot stills, usually distilled twice. Cognac is double-distilled in pot stills too. A lot of Irish whiskey goes three times. Tequila has to be distilled at least twice, and many mezcals are still made in small copper or even clay pots.

A column still runs continuously. Wash goes in near the top, steam comes up from the bottom, and plates inside the column strip and separate the alcohol again and again on the way. The design most people know was patented by Aeneas Coffey in 1830, which is why you still hear it called a Coffey still.

Columns can reach very high proof and make a cleaner, lighter spirit. Vodka depends on that. Most bourbon runs through a column first, then through a doubler or thumper, a second pot-style step that rounds it out.

Copper is not just tradition. It reacts with sulfur compounds in the vapor and pulls them out, so the spirit comes off cleaner. Stills made mostly of steel often have copper somewhere in them for exactly that reason.

Shape matters too. A tall neck sends more heavy vapor back down to redistill, giving a lighter spirit. A short, squat still lets more of it through, giving a heavier one.

Most labels do not tell you what kind of still made the spirit. A few do. Irish single pot still whiskey is its own category, made from malted and unmalted barley in pot stills. Some bourbons, rums and brandies call out pot still on the label as well.

The clearest way to taste the still is with an unaged spirit, where there is no barrel to hide behind. Blanco tequila, gin, white rum. Try a pot-still spirit next to a column-still one of the same kind at home, and notice the weight and texture as much as the flavor.