Bentonite, or bentonite clay as it is sometimes referred, is a fining agent that has long been used in the winemaking process. It is a grey powder that is mixed with hot water and added to the must prior to fermentation. It is recommended to use 2 tsp. in 1/2 cup warm water, and the resulting slurry to be mixed thoroughly into 5 to 6 gallons of wine must. The bentonite will bind with large molecules in the must and settle out, leaving clear and clean wine that is more stable than untreated wine. This wine can then be easily racked off of the sediment for further aging and clarification.