What causes clay to stick to the molds? There are several factors that can cause your clay to stick, including clay residue, too little mold release, too soft clay and warm temperatures, all of which are discussed below. Clay Residue - Molds can be cleaned with waterless hand cleaner or rubbing alcohol and a soft brush. Make sure the mold is thoroughly dry before using it again. Not enough mold release - It is easy to use too much cornstarch. Use a clean, soft brush to remove any excess powder from molds, or rinse them under running water and allow to air dry. The water will dissolve the cornstarch. Soft Clay - Mushy or sticky clay can be leached to remove excess plasticizer before molding. Warm days - More problems with sticking occur on hot, humid days during the summer months. The simplest solution is to pop the filled mold into the freezer for a few minutes to make the clay firmer and more easily removed. Warm hands will also contribute to sticky clay.