Bentonite is a type of clay, known as aluminosilicate. Its technical name is Montmorillonite. It's found with various minerals attached to it, such as sodium, calcium and magnesium. It was originally found in Fort Benton, Wyoming. When used in wine making, it is stirred into the wine to remove proteins and other haze causing particles. It works through adsorption. This means that it attaches itself to a particle, and together they are too heavy to stay in suspension, falling to the bottom of the carboy, leaving the wine clear and stable. Bentonite settles out so completely that it does not leave any residue of taste or colour behind. It is best to add bentonite on the first day, prior to pitching the yeast. When bentonite is added on the first day, it disperses through the wine and most of it settles to the bottom within 24 hours. At the end of 48 hours, however, the bentonite is back in circulation. This is because as the yeast ferments the sugar, CO2 is being processed in the wine. The bentonite is surrounded by a bubble of gas and floats up to the surface of the wine. When the bubble bursts, the particle of bentonite drops back down to the bottom of the carboy, all the time working to absorb the other particles clouding the wine, a process known as gas nucleation. In this way, the bentonite is circulated around the wine continuously for days, doing its job. Bentonite can also help make sure that the wine is stable. Stable means that it won’t change in appearance, taste, aroma, or chemical composition while in storage.