Can you use GlassCast thickened with Fumed Silica Powder to separate from un-thickened GlassCast. EG. Imagine a river coat rack hanging on a wall, with three layers top to bottom. When casting, and I try to separate the top and bottom layers with a third middle layer, the middle layer just bleeds into the top and bottom layer. I wondered if a thickened layer would prevent this.