1. Place the dry ingredients in a large mixing bowl. Add the cool water, and stir slowly to allow the sugar to dissolve.
2. Mix on low speed at first, increasing to high speed over several minutes. Beat until the icing is fluffy.
3. Keep the frosting covered with a damp towel and some plastic wrap until you have time to use it.
4. Divide the frosting into smaller containers and mix with food coloring for several colors.
5. To use for piping, put a tip in the bottom of a disposable pastry bag. Using a coupler will allow you to change tips with ease.
6. Use a tall, heavy-bottomed glass to hold the pastry bag while you add the frosting. Take care not to fill the bag more than half full.
7. Close the back of the pastry bag with a twist tie or spring clip, to keep the icing from backing up over your hand when you squeeze it.