Pot Still Vs Column Still
Spirits have to be distilled (separation of alcohol from water in the fermented liquid) to get alcohol with the desired flavours and aromas. This is done through an apparatus called the still. The still can be of two types:
A pot still is also called alembic still. It is typically made from copper. Copper was used traditionally because it is a good conductor of heat and it extracts sulphur from the distillate. The classic pot still has different components; the bottom part is called kettle where the ferment is heated. The ferment is evaporated and the vapours travel through the swan-shaped neck and it reaches the worm, a spiral-shaped copper tube attached to the condenser where the vapour is condensed to a liquid.
Generally, aged spirits (like whisky, tequila and rum) and crafted spirits are made in pot stills. Pot stills also help add desired congeners to the spirit responsible for aromas and flavours in the spirit
A column still is called coffey still, or continuous still. It is relatively contemporary and designed in such a way that pure alcohol is derived directly from the ferment. It is used for industrial and mass commercial alcohol production.
Column stills are made from stainless steel and comprises a tall column structure attached above the top of the boiling kettle designed to attain purer vapours. It is divided into chambers using perforated plates. The still is constantly heated at the bottom, so when the ferment is poured from the cooler top part and when it hits the steam, it vapourises and sends the alcohol back to the top. When the alcohol carrying vapour passes through the perforated plates, it condenses the heavier particles and only alcohol carrying vapours continues to the top, travels through the pipes attached to the condensers where the vapours are condensed to the desired liquid.
Column stills are used to derive white or neutral spirits like vodka, gin and white rum.
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