This article is from the WineMaking FAQ, by malak@CAM.ORG (Don Buchan) with numerous contributions by others.
{As I understand it, bentonite is a clearing agent. However, in the
instructions for my kit it says to add the bentonite at the same time
as the yeast. Why?}
It helps clear off millions of dead yeast cells during the primary
fermentation; doing so optimizes the actual clearing process by taking
care of a lot of it before you even try. It also helps avoid foul
smells from decomposing yeast -- a potential problem when your wine is
in the carboy for several weeks or even months -- when you transfer the
wine into the secondary.
In about 5 gallons, about 25 to 50 grams of bentonite is used.
Bentonite should be easily available from your brewing supply shop.
 
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