Most major distilleries use chill filtration on their flagship whiskeys. Even their “non-chill filtered” whiskeys usually have been filtered with a carbon filtration system. The most economical way of doing this is to decide what works best for your end product, purchase that system or systems, and set it up for all of your filtration needs. Changing the way that filtration is done is very time consuming and adds expense to the final product. This is a shame because filtration can be a very beneficial process to the final whiskey. In this blog, I am going to look closer at filtration and its benefits. To prepare for this blog, I spoke to Andrea Wilson, Vice President of Maturation at Michter’s Distillery. Her background includes a Masters Degree in Chemical Engineering and many years of experience in the industry. 

I will start by saying more about carbon filtration. This process has been around for many decades and was the most common system used in the 1940s, 50s, and 60s. It is a process where you add activated charcoal to your dump tank full of whiskey and agitate it. The charcoal will attract oils and other compounds which attach themselves to the charcoal. The whiskey is then filtered through a paper filter and the whiskey looks bright and clear when bottled. The paper filters remove the charcoal from the barrels as well as the activated charcoal used in the filtration process.

Chill filtering is a more common practice in the whiskey industry today. It became the most common practice during the 1980s when Japan was the major market for Bourbon and the industry was getting complaints about cloudy whiskey. When whiskey gets cold, the natural oils left in the whiskey from the distilling process begin to coagulate making the whiskey look cloudy. To clean up the Bourbon, the distilleries started to chill filter the whiskey. 

Andrea Wilson has told me that the first thing to remember, is that filtration starts with an up-front investment. The distiller does a lot of different things to create the flavors they want in their whiskey. 

There are six sources of flavor – 1) grain, 2) water, 3) fermentation, 4) distillation, 5) maturation, and 6) bottling. Filtration falls into the sixth source of flavor. Since the distiller has spent so much time and money creating the flavors in the other five sources of flavor, they don’t want to filter out the flavors they want in the bottling process. 

However, there are ways to adjust the filtration system to remove flavors you don’t want and let the flavors you do want remain in the whiskey. Filtration can also be adjusted to highlight certain flavors as well. This is done by changing the variables such as temperature, the surface area of the filters, the micron size in the filter, the pressure used in the filtration system and the type of material the filter is made from. 

The general rule is that whiskey over 46% ABV (92 proof) does not need chill filtering to prevent floccing – the cloudy look in cold whiskey. That does not mean that high proof whiskey should not be chill filtered. Filtration can make overly tannic whiskey more palatable by removing some of the tannins. Filtration can highlight flavors such as fruitiness or spiciness. Filtration does remove some of the color, but it can be done to minimize that loss. 

The equipment works about the same way as it did in the 1980s. The big changes have come from improved filter medium and improved electronics allowing smaller size and more control of the process. Not all distilleries make the investment in chill filtration systems as they are not cheap, but all of the major distilleries do have at least one system in place. 

As I said, the most economical way to do filtration is for a company to choose a system that meets their needs and use it in a single setting for all of their whiskey. However, by doing so they are missing out on a way to make individual whiskeys unique in flavor profile even though they may come from the same mash bill. 

Michter’s has shown that this is possible when you consider that the barrel proof rye or Bourbon does have uniquely different flavor profiles from the standard rye or Bourbon even though they are coming from the same mash bills. This difference is more than just the proof differences. They do filter the whiskeys differently. They have taken the time to look at each whiskey in question and decide what they want removed from the flavor profile and what to highlight in the profile. This takes time to do and adds expense, but they feel it is worth it in the end.

Filtration is an important part of producing a brand. It can take an overly bitter and tannic whiskey and turn it into a sweet caramel and fruit elixir. Smaller distilleries may want to explore the filtration process more in order to help distinguish their whiskeys from that of their competitors.