A sweating cake can ruin your icing application and turn a tasty treat into an unsightly mess. To pull off a flawless presentation, use proper cooling and storage techniques to prevent the sweats from even starting.
Place your cake in a cool room for at least an hour right after bringing it out of the oven. Most kitchens tend to get humid after baking, which can contribute to cake sweating. If you must cover or wrap your cake, use a large, airtight plastic bag.
Apply the icing to the cake only when it is cool. Applying the icing when the cake is above room temperature will generally result in a soggy cake with melted icing.
Keep your iced cake on the counter at room temperature. Cakes tend to become too cold in the refrigerator, which means they can start to sweat when you bring them out again and they hit the room-temperature air.
Tips
Store your cake in a cardboard box when traveling with it.
Spray a few spritzes of alcohol, such as vodka, on your cake in order to prevent condensation and further bind your icing. Avoid using flavored alcohol since this may affect the flavor of your cake.