Physical hazes and their associated precipitation problems are much more difficult to deal with. These physical hazes require liquid/liquid separation as opposed to the elimination of solid particulate matter which is usually associated with filtration. The liquid phase requiring removal from whisky comprises ethereal oils. Their removal is made more complex because they may show up as a haze in bottled product, despite the fact that the product may have been perfectly bright at the time of bottling.
Whisky shipped to countries with low ambient temperatures may throw a haze due to the temperature reduction. To avoid this problem, whisky can be chill filtered; typical temperatures used vary between zero to plus 4 degrees C.
The sheet filtration process used in the whisky industry may be in lenticular or sheet filter format and either single or two stage:
Single stage filtration takes place at 0 - 4 degrees C when bottling at 20 degrees C.
Two stage filtration is described on separate tab.Download PDF