Powdered Sugar

Powdered sugar, also called confectioners' sugar or icing sugar, is made by milling granulated sugar into a fine powder and typically contains 2 to 5 percent of an anti-caking agent such as corn starch, potato starch or tricalcium phosphate to keep it from clumping; Canadian regulation caps starch or anti-caking agents at 5 percent. It is sold in grades of fineness, most commonly labeled 6X and 10X, with a higher number indicating a finer powder, and home cooks can approximate it by grinding granulated sugar in a coffee grinder or with a mortar and pestle. It is used mainly for icings, frostings and cake decoration in home baking and for fast-dissolving applications in industrial food production, and its anti-caking additives mean it cannot always substitute directly for granulated sugar.