What is Pot Still distillation?

You can imagine it as a super large, somewhat oddly shaped copper kettle.

Distillers pour the fermented, beer-like liquid (which we call 'wash') into this large pot, and then begin to heat it from below.

As we all know, alcohol has a lower boiling point than water (alcohol boils at around 78 degrees Celsius, while water boils at 100 degrees Celsius). So, when heated, alcohol turns into vapor first, rising up along with some water vapor and flavor compounds.

This large copper pot usually has a long, curved neck, known as a 'swan neck'. As the vapor travels up this neck, the process acts like a filter: heavier, less pure components might cool down and fall back into the pot midway. Only the lighter, purer alcohol vapor successfully 'climbs over the mountains' and enters a cooling device (condenser).

Once the vapor encounters cold, it turns back into liquid. The liquid collected at this point has a much higher alcohol concentration than before.

This completes one full pot still distillation. Typically, spirits like whisky require distillation twice (some Irish whiskies even three times). The second distillation involves taking the high-proof spirit from the first distillation and repeating the process described above in the pot, resulting in an even higher alcohol content and a purer spirit.

Key points:

1. Batch by Batch: Pot still distillation is done in batches (one pot at a time). After one batch is distilled, the spent material in the pot must be cleared before a new wash can be loaded for the next batch. This makes it less efficient and more costly.

2. Flavor is the Soul: So why use this seemingly 'clumsy' method? The key lies in – flavor! Precisely because of this 'imperfect' distillation method, it retains many complex flavor compounds (esters, phenols, etc.) from the raw materials (like malt) and the fermentation process. These ultimately become the captivating floral, fruity, smoky notes found in whisky. The shape, size, and angle of the swan neck of the still all influence the final flavor, making each distillery's pot still a unique and cherished asset.

Therefore, most single malt whiskies we drink, whether Scottish or Japanese (like Yamazaki, Yoichi, etc.), are produced using this type of pot still. Although it's slow, it's precisely this meticulous, slow-crafting method that creates spirits with complex flavors and distinct personalities. Besides whisky, many high-quality brandies (like Cognac) and rums also use it.

In summary: Pot still distillation is like using a large stew pot to slowly distill spirits batch by batch. While slow, it maximizes the preservation of the spirit's flavor and character, making it the 'soul' behind producing high-quality, complex-flavored spirits.