Experienced Mould Maker Is Already Using Special Fibers
Some experienced Mould Maker have solved this problem by using an embedding process that uses a special soft cotton fiber sandwiched between an alginate mold and its gypsum shell. Because alginate does not stick to anything, embedding the fiber in the alginate surface prior to coagulation of the fiber crystallizes the hull of the damp gypsum, which binds as the gypsum solidifies.
The process starts with alginate retarder spraying the surface of the alginate to keep the alginate solidified and keeping it sticky long enough to bind the cotton when it comes into contact with its surface. Therefore, when the alginate has cured, the cotton fibers actually remain fast from the alginate itself. Then, with a plaster bandage set, these two materials will trap the cotton fiber between and lock the mold together, so the alginate and gypsum shells can be erased at once.
But no cotton fiber will do it. Most cotton is too tight to be fluffy, and cotton fibers can not be placed on alginate surfaces. We found that veterinary cotton is by far the best material for this process and we specialize in its excellent properties. Its fibers are very soft and easily embed in the surface of uncured alginate.
When making large molds with alginate (dental impression material) - for example, face casting or trunk casting, once removed from the mold, a master or shell mold is required to hold the alginate mold. This is because alginate is rubbery rather than rigid and will collapse itself. The alginate molds were used to make the master, either using overlapping gypsum bandages or, in the second technique, cheese cloth impregnated with rapid setting gypsum. Both methods are satisfactory.