The wine coming out of the fermentation, but especially the must coming from the pressing, are never a particulary attractive liquid. Because of the suspended substances they contain, they are turbid and easily unstable; this means that, under certain conditions, they are exposed to alteration or degradation processes.
Clarification, despite the name suggests a modern process, is a very old practice, known since ancient Roman times and applies to all types of must and wine. It involves the smallest residues that remain in suspension and which make the liquid turbid, un stable and exposed to organoleptic mutations. The introduction of particular substances, called clarifying agents, allows these ones to aggregate with the particles in suspension and cause them the precipitation by gravity on the bottom of the container, thus making the liquid transparent.
The main clarifying products can be either of organic origin such as albumin (i.e. the the egg white), vegetable gelatin, animal gelatin and casein (a derivative of milk) and of mineral origin such as bentonite and colloidal silica. Each of them has particular characteristics therefore their use will vary depending on the type of winemaking and the final product.