When turning a cake out onto a rack to cool, lay a smooth kitchen towel on the rack, then dust the top of the cake with powdered sugar, invert it onto the cloth, and remove the pan. Air can circulate freely under the cake, allowing steam from the warm cake to dissipate as the cake cools. The powdered sugar will keep the surface of the cake from sticking when it is lifted from the cloth, and the cloth will keep the rack from making deep lines on the surface of the warm cake.