It is essential that there are no visible particulates once the whisky has aged, so coarse filtration is necessary after the vatting stage. When the whisky has reached its desired maturity, it is disgorged from the cask and goes through a process of particle filtration. This removes any residual particles, typically the char from the burned inside of the cask. Due to the volume of whisky that will need to be filtered, a coarse particle removal stage is required first, then advancing to a smaller micron particle filter. This will allow the large volumes to be filtered quickly before a finer stage of filtration to ensure a char free whisky.
Coarse Particle Removal
When source water is particularly dense with large solids, it calls for a solution of filtration to withstand higher flow rates and utilise higher surface areas to rid water of heavily populated particles.