This doppled color effect can be done with thinned royal or buttercream icing or diluted icing color. Use a crumpled paper towel, waxed paper or plastic wrap – each will provide a different look!
Dip crumpled paper towel, waxed paper or plastic wrap into diluted icing color or thinned icing. Test on parchment or paper towel; lightly press against cake surface.
Continue sponging color until surface is covered. If some areas look too light, repeat sponging technique in that area.