Kim - from Mayport, PA
Crumb coating is a thin layer of thinned icing placed on the cake first and allowed to harden ("crust"). The crumb coating is used to keep cake crumbs away from your final icing, as well as to mask chocolate and other colored cakes underneath rolled and other icings. Start by removing a small amount of frosting in a small bowl to use as the crumb layer. The larger amount will be used for the final coat. Add additional liquid from the recipe or corn syrup to thin the icing. Brush off any loose crumbs with a pastry brush before starting to crumb coat the cake. With an angled spatula, spread a thin, even layer of the icing on the cake. Start with the top and then move to the sides; this will force loose crumbs to the base of the cake. Be sure to press firmly to remove air bubbles which could pop out of the top icing. Allow the cake to stand until the icing hardens, about 40 minutes at room temperature, or about 15 minutes in the refrigerator. Then you're ready to ice with a final layer of icing.