Why are Clearing Agents used in Wines?
Good quality wine should be clear. If you are new at fermenting wine, then you must have experienced times when your wine came out cloudy. A cloudy wine means that there are small particles that have suspended within the liquid that formed during the fermentation process. This is normal and wines eventually clear up through racking, but if it doesn't, then you can use fining agents for your wine to aid in clarification.
To get all the suspended particles out, fining agents are used to bond with the charged solids thus forcing them to settle in the bottom. In the past, fining agents would include fish bladders, clay and bull's blood. It does sound nasty, but you don't really have to use them today as there are chemicals available to help clear your wine. There are several types of fining agents that winemakers use when making wine today. (more info below)