In a perfect world, when you cover a cake with fondant it hardens to perfection and becomes a work of art. Time, temperature and humidity can work against you, however, and cause your fondant to become sticky and start to sweat. Preventing this from happening without creating the equally frustrating problem of fondant that is too dry requires the right ingredients, process and a few fondant tricks.
Control air temperature and humidity levels before and after covering a cake with fondant. A warm, humid room will draw moisture from the fondant and cause sweating. Turn on your air conditioner, or use a room dehumidifier and a fan to maintain cool, dry air temperatures.
Remove stickiness that can lead to sweating by sprinkling 1 to 2 teaspons of powdered sugar or a combination of half powdered sugar and half cornstarch on your work surface and rolling pin before rolling fondant.
Store a fondant-covered cake in a pastry box at room temperature. Fondant seals moisture in your cake so you can store it at room temperature without worrying about your cake becoming dry.
Wrap a fondant-covered cake in plastic wrap before refrigerating, if it has a fruit filling that requires refrigeration to prevent spoilage. Bring a refrigerated cake back to room temperature in a cool room before removing the plastic wrap. This will slow warming and prevent moisture in the cake from seeping through the fondant.
Freeze a fondant-covered cake by allowing the fondant to harden just slightly before wrapping it in plastic wrap. Set the cake in your freezer for 20 minutes, then remove, wrap and return the cake to your freezer. Thaw a frozen cake in your refrigerator and then bring it to room temperature before removing the plastic wrap.