Commonly used as leavening in baking, and to help in beating egg whites. To substitute for one tsp of double acting baking powder, use 1/2 tsp baking soda and 1/2 tsp Cream of Tartar.
For craft dough, mix together 2 cups flour, 1 cup salt, and 2 tablespoons Cream of Tartar in a pan. Stir in 2 cups water, 1 tablespoon oil, and a few drops of food coloring. Cook and stir over medium heat until it forms a ball. Cool and store in a plastic bag until ready to use. Use 1/8 teaspoon per egg white to make souffles, meringues, angel food, chiffon cakes, and candy.