Run sugar icing is the classic cookie icing. It is a smooth textured icing that forms a very hard crust. It is made by taking royal icing at it's fluffiest form and adding water to make it flow. When it dries, you can stack the cookies. This type of icing takes several hours to dry. The icing has a simple, flavor with some crunch. First, mix-up royal icing using a recipe or a mix. After the royal icing has been mixed, Divide the mixture into several small containers and cover with wet towel. Add a small amount of water to each batch until it us just barely fluid, NOT watery. Test consistency by dropping a small amount from spoon onto waxed paper. It should smooth itself in about 10 seconds. If it runs too much, add more powdered sugar. If it is too thick, add a bit more water. Remember: keep this icing covered when you are not using it. It dries out quickly. Place the icing in a bag with a tip #3 or #4. Outline the area to be covered. Quickly fill in the outline. If the icing is running off the cookie, too much water was added to the royal icing. If the icing is not smooth, add a bit more water to the royal icing. When icing crusts, pipe adjoining color. For added dimension or outlining, allow icing to harden (several minutes) and pipe on the top.