Filtering Your Spirit With Carbon

Which ever way you make spirit, it is absolutely essential to filter it before mixing it with any flavours. This is referred to as polishing your spirit. Brewers Choice currently stock the EZ Filter system and Column Filters to do this job, but any filtering system is better than none.

The best ingredient to filter your spirit is activated carbon. Activated carbon is used in many areas for filtration because of its effectiveness, from processing waste water to gold refining to making bourbon. Activating carbon produces carbon that resembles a sponge, with millions of tiny passages and holes in it, and presents a huge surface area for molecules to stick to.

The activated carbon can then work as a type of "molecular sieve", trapping the molecules which are larger than ethanol. They become trapped in the pores inside the carbon, and also by surface energies on the carbon. So it won't remove methanol, but will remove larger molecules such as aldehydes, aminos and fusil oils (not good for your health and the taste of your spirit).

Diluting Your spirit First

Make sure that the alcohol strength is less than 50% before polishing it - the carbons will work more effectively. There are several reasons for this.

• The fusels do not dissolve as well in lower-percentage alcohol. If your spirit is diluted, and the fusels are therefore less dissolved, they are then more easily captured by the carbon.
• At the diluted ratio, the "nasties" are also diluted and become easier to collect.
• If the Alcohol is too strong, the alcohol can attack the carbon and cause impurities to be leached out the wrong way, i.e. from the carbon to your spirit.

Always use clean water to dilute as this reduces the amount of impurities the carbon has to remove. Distilled water is best, but clean tap water is satisfactory (and more economical).

Which Carbon to use?

Activated carbon is available at Brewers Choice stores in two forms Granular and Pellets.

Pellets

When using a filter to polish your spirit, the best carbon to use is activated carbon pellets. Pellets have much better filtering properties than the granular carbon. Pellets look like small pencil leads. The pellet-isation of the carbon results in a carbon far more effective inside a filter.

Granular

Generally, granular carbon is placed in the spirit for a length of time to soak (eg. add to 10 litres of spirit and leave to soak anywhere from 2 days to 2 months) before filtering the spirit. Agitation of the spirit will assist the carbon granules to collect much of the impurities. Granular carbon can be used in a filter but it will not be as effective as filtering through pellet carbon.

Which ever carbon you are using, make sure you wash your carbon before using it, to remove the carbon dust.

When filtering, the molecules trapped by the carbon are sometimes held fairly loosely, so do not try to filter too fast. The molecules can be washed off the carbon and back into your spirits.

Final Filtering

Make sure you always pass your polished spirit through a paper filter, as a last step. Many of the impurities are held by very fine carbon dust - and will still affect the flavour. Even spirit that appears crystal clear will leave a grey mark if run through a filter paper. Just use a filter paper or some tissue paper or cotton wool in the bottom of the filter to trap the loaded dust. Brewers Choice Z-filters have a filter paper at the bottom of the filter for this reason.

Adding Carbon to the Wash

Some brewers add activated carbon  or Turbo carbon to the wash (eg with the sugar) during fermentation. This helps to take out some of the unwanted impurities as they form. Make sure that you filter/decant off this carbon with the yeast, when you remove the wash. The best way to ensure the carbon is removed with the yeast at the completion of fermentation is to use Turbo Clear.