Traditional breadmaking can last many hours, and bakers would often have to work through the night in order to sell fresh bread in the morning. In the 1920s, bakers in Vienna began to experiment with breaking the work into two periods, a daytime stint for mixing, fermentation, and molding into loaves, and then an early-morning baking. During the night, the formed loaves were kept in a refrigerated chamber. Cool temperatures slow the activity of microbes substantially; yeasts take 10 times longer to raise bread in the refrigerator than at warm room temperature. Refrigeration of dough is therefore called retarding, and the cold chamber a retarder. Retarding is now a common practice.