Argols refers to crude tartar, a substance that is a byproduct of winemaking. When grape juice ferments in barrels, a sediment forms at the bottom of the barrels. This sediment, which is primarily potassium bitartrate, is collected and purified to produce cream of tartar, a common ingredient used in cooking and baking. Argols can also refer more generally to any sediment or lees that accumulate during the fermentation of wine.