Pyros Mold Materials Comparison ChartWe offer a selection of mold-making materials. Our emphasis is on speed, cost, safety and ease of use. See our tips for choosing a mold material:About Mold Materials What are you Molding? How Big is Your Project? |
1. About mold materialsMolds for Freeze 'N' Fuse projects must remain flexible at cold temperatures. This limits our materials to rubbers and certain plastics.Rubbers Rubbers are materials characterized by long-chain molecules that are linked together in an elastic mass. Several different families of rubber are used in commercial molds: Latex - The
earliest rubber
known, this is a natural resin from tropical trees. It is a
one-part material that is simple to apply, but it takes many coats to
make a mold. If you have more time than money, this makes an
excellent mold.
Silicone - A huge family of rubbers with many tailorable properties. Makes flexible molds with very good lifetimes. The most durable silicones are cured with Platinum, which makes them expensive. Less-expensive silicones use Tin or Peroxide cures. We feature brush-on, pour-on, and putty type silicones with easy measuring and mixing. Polysulphide - The first rubber to be synthesized by people, this is still an excellent material that is used to cast wax models in metal foundries. It is smelly, sticky and difficult to use. Urethane - A very useful family of rubbers which can be made in a wide range of hardnesses. Must be mixed precisely and used promptly. It makes very durable molds but requires a mold release and is extremely sensitive to moisture. Plastics Plastics do not exhibit the soft elastic properties of rubbers, but may still be flexible enough for molding. Back to top 2. What are you molding?This will affect several things: the type of material you can use and the type of mold that you make. Brush-on molds require more labor but are better for models with large undercuts that can benefit from a "glove-type" mold. Simple flat models are easiest to cast with a pourable silicone, using a 1-part or 2-part block mold. Putties or caulk are best for casting natural objects with large porous surfaces, like bark or pinecones, because they don't sink into every crevice.Back to top 3. How big is your project?As projects size increases, the cost of molding materials becomes very important. You could cast a big block mold of a tree trunk, but it would cost you hundreds of dollars in pourable silicone. An equally effective mold could be made with about 100 dollars worth of Pyros Purple Putty, or less than 25 dollars of Silicone 1 Caulk. For large production runs, the cost of the mold is negligible compared to the time spent filling it and producing finished work. For one-of-a-kind and prototype work, making the mold is a major part of the expense.Back to top |