Baking Powder is baking soda to which an acid and filler have been added. Once added to moist baked goods, a chemical leavening response occurs. We offer two types of baking powder, single acting and double acting. The primary difference between the two has to do with when bubbles are produced in the batter. In double acting, the dough bubbles twice – once in the raw batter and again during backing. The same amount of baking powder is used whether single or double and you can use either in a recipe as an equal substitute. Try double-acting powder in your recipes that need to rest before baking such cookies or breads, where the loss of leavening ability is required.