Combine egg whites (at room temperature) and cream of tartar in a mixing bowl. Beat at medium speed of an electric mixer until foamy. Add half of sugar, mixing well. Add remaining sugar; beat at high speed of electric mixer 5 to 7 minutes or until stiff peaks form.
Divide frosting according to the number of different tints desired; add paste food coloring. Frosting dries quickly; keep containers covered with damp towels until ready to use.