The smooth, uniform shape of fondant is unmistakable. Fondant is a popular cake icing, often found on wedding cakes. You can place fondant over regular buttercream or other frosting. Shapes, such as flowers, can be cut out of fondant to make cake decorations. You need a hardened fondant for this, or your decorative shapes may move, shift or wilt. You can harden fondant naturally with air or you can use other methods to decrease the drying time.
Roll your fondant out to your desired thickness. Usually this will be around 1/4 inch thick. Use a rolling pin for this. If it is too hard to roll out, place the fondant in a microwave-safe dish and heat in the microwave for 10 seconds. This will make it easier to work with.
Leave the fondant out, unsealed, on a drying rack. The air should be able to circulate on all sides and will naturally harden this way. It can take up to three or four weeks for the fondant to completely harden, especially if you are in humid climates where it takes things longer to dry out because of the moisture in the air. Placing a fan next to the fondant may help decrease drying time.
Preheat your oven to the lowest heat setting, if you don't have time to air dry the fondant. Place the rolled fondant on a baking tray and put it in the oven. Heat for a half hour and then flip the fondant. Adjust the heat if you have thicker or thinner pieces, or if you notice the fondant is hardening faster than expected.
Mix a hardening agent into the fondant to dry it within 24 hours. Kneed the fondant and the agent together and roll it out to dry. The most popular agents are Gum paste, Gum-tex and Tylose. The mixture should be 50 per cent fondant and 50 per cent hardening agent unless the product instructions indicate a different ratio. These hardening agents should decrease the hardening time of your fondant dramatically. You should have a stiff fondant within 24 hours. The downside to a hardening agent is that it may make the fondant have an unpleasant taste.