Carbon that is produced by heating wood or other organic substances in the absence of oxygen. When the oxidation of carbon is carried out by high temperature steam, millions of pores between the carbon atoms are created and the charcoal is classified as “activated”. For context, around one gram of activated carbon has a surface area of just under 3000 square meters.
From a distiller’s perspective, the “activation” process creates a porous, sponge-like structure with a large surface area where many types of contaminants can bind to, removing them from the liquid (in essence a molecular filter and not dissimilar to a Brita filter for domestic use).
The density, size and distribution of the pores determines what compounds will be absorbed and which ones will pass through. Other than using it to clarify a spirit (for example to create a Cristalino Tequila or a White Rum), by using different types of activated charcoal, distillers also shape the final aroma and taste profile of a spirit.
Tennessee Whiskey makers were said to be the first to use charcoal to filter spirits and famously, the Lincoln Country process is where famous names like Jack Daniels and others are filtered through a column of maple wood charcoal. Today, activated charcoal is widely used in the production of Vodka and Rum, while many Tequila producers are now using commercial grades of activated charcoal as well.