Fondant is a pliable dough made from sugar. It can be rolled out and used to cover a cake, cut into shapes or used to decorate cupcakes. Fondant is very sticky when rolled, so a coating of powdered sugar is often used on the rolling surface to keep the dough from sticking. Powdered sugar tends to get all over the fondant and does not brush off, especially on darker colors.
Place your fondant-covered cake on a clean work surface. Ensure that there is no powdered sugar present that can stick back onto the cake after it has been cleaned off.
Take a small ball of leftover fondant. Ensure you use the same color fondant as the cake so that color does not transfer. Rub the fondant on the cake with the ball of fondant in your hand. Smooth it over the cake and concentrate on the areas where there is powdered sugar. Buff out any powdered sugar spots that can be seen on the fondant surface. Do not reuse the ball of fondant for decorations.
Pour a small amount of vodka into a bowl. Dip a cake decorating brush lightly in the vodka. Paint a thin coat of vodka over the surface of the fondant. Ensure you cover the entire cake, since vodka will leave a sheen on the surface. The powdered sugar should lift away from the cake. If you have a cake decorating airbrush, you can fill it with vodka and spray the cake.