Page 64 - Craft of Whiskey Distilling

AmErICAn DIstIllInG InstItutE | 53
If the distiller is going to vat his/her whiskey, the proportions from each barrel in the mix need to be worked out in small quantities by a panel of tasters. Once the proportions of each barrel of whiskey have been decided, the large quantities must be poured into a vat and mixed thoroughly. If the whiskey is not going to be vatted, then it can just be placed in the vat, ready for diluting.
Diluting: The whiskey straight out of the barrel will be between 55 and 65% abv, and it will require diluting to bottling strength. Whiskey is diluted to somewhere between 40 and 50% abv for bottling.
Before the distiller dilutes the whiskey right down to bottling strength, it must be de- cided whether the whiskey is going to be treated with activated carbon or not. Most whis- kies are not treated with carbon, but if one is, it must only be diluted to 4% above the final bottling strength. It is further diluted after the treatment to the exact final percent alcohol. This is because the carbon treatment lowers the percent alcohol slightly, so there needs to be some leeway to take this into account.
If the whiskey is not going to be treated with activated carbon, but is going to be fil- tered, it should only be diluted to 2% above the final bottling strength. This is because the whiskey could pick up a small amount of water in the filtering process. Again, the final dilution to the exact bottling strength is done after. Diluting should be done with distilled or Reverse Osmosis (RO) water to avoid the water imparting any taste, and to prevent any mineral precipitation in the bottles.
Activated-Carbon Treatment: Most whiskies are not treated with activated carbon, but some are characterized as very mild, and a certain amount of this mildness is achieved by exposing the whiskey to activated wood charcoal. Incidentally, other types of activated carbon would strip too much flavor and aroma out. That’s why wood charcoal is the type of carbon used. In some cases, the whiskey is poured through a deep bed of carbon, and in others the carbon is added to the vat, and it’s gently agitated every few hours.
The optimum percent alcohol for carbon to work most efficiently is 38% abv. However, that’s too low for any whiskey so the whiskey is diluted from its barrel strength to bring it closer to optimum, without going too low, before any activated-carbon treatment is done.
As mentioned above, the action of the carbon on the whiskey lowers the percent alco- hol slightly so it’s important that the whiskey not be diluted to its exact bottling strength before carbon treatment. Keeping it at 4% above the final bottling strength ensures it doesn’t drop too low as a result of the carbon. After the carbon treatment and the filtering, the percent alcohol can then be adjusted to the exact final value
Filtering: Whiskey doesn’t need much in the way of filtering. It’s simply a matter of removing the wood and char particles picked up from the barrel during the years of aging. It’s purely for aesthetic reasons, as having a bottle of whiskey that was slightly cloudy from suspended burnt oak particles would not be very appealing.