Wilton's recipe for royal icing includes meringue powder, powdered sugar and water. Royal icing is safe to eat and is used to make hard decorations, such as flowers, and to cement decorations to an iced cake. This type of icing is not used to ice cakes.
In a large bowl or in a heavy duty stand mixer, combine 3 tablespoons of Wilton's meringue powder, 4 cups of powdered or confectioner's sugar, and 5 tablespoons of warm water. Mix until the icing forms stiff peaks. If using a stand mixer, the mixing time is about 7 to 10 minutes on low. For a hand mixer, beat on high for about 10 to 12 minutes. To make the icing stiffer, or when using a large stand mixer, omit 1 tablespoon of water. For pourable royal icing, add 1 teaspoon of water per cup of icing,
When making Wilton's royal icing, it is crucial to ensure all bowls and utensils are grease-free. Any shortening, grease or fat on the spoons, mixers or bowls causes the royal icing to lose its stiff consistency. While working with royal icing, keep the bowl of icing covered with a damp towel to prevent it from stiffening prematurely. When piping flowers or attaching decorations, wrap the icing bag and decorating tip in a small, damp cloth in between uses.