Want to create a tray (12x12x2) silicone mold for cold process soap. Which type of silicone should I buy? Secondly, my mother-form is a top-decorated hollow box that I will tip over and pour the silicone over. I've made the frame, but I think I need to fill the box with SOMETHING like urethane or polyester so that it makes firm, all-over contact with the underlying piece of glass (bottom of mold frame). Some type of filler...but what exactly? Any help is appreciated.
....If the box is made of wood use a wood sealer...same as you would use on a patio deck or when water could enter into the wood and cause rot...i.e shower area of a bathroom. Another possibility would be floor wax...I have found Future is the easiest to use. Both of these need to be thoroughly dry before pouring the mold. HS-2 & HS-3 is some awesome stuff! I have yet to find anything that caused a bad reaction when used in molds or mold boxes.