All young wines are hazy after fermentation due to tiny molecules such as proteins, tartrates, tannins and phenolics. Whilst natural and harmless, many people have come to expect and like their wine to be clear. To help the accelerate the clarification process, which if given time can settle naturally, winemakers use fining agents.
Some common fining agents include casein (a milk protein), albumin (egg whites), gelatin (animal protein) and isinglass (fish bladder protein).
Whilst fining with casein and albumin is usually acceptable by most vegetarians, all four cannot be considered vegans friendly as tiny traces of the fining agent may be absorbed into the wine during the fining process. Carbon, bentonite clay, limestone, kaolin clay, plant casein, silica gel, and vegetable plaques are all suitable alternatives.