Different between Tin cure and Platinum cure liquid silicone
The chemical difference between tin-cure (condensation cure) and platinum-cure (addition cure) silicone mold making rubbers lies mainly in the metal used to catalyze or cure the base rubber. The metal tin is used to catalyze or cure tin silicone, and platinum is used to cure platinum silicone rubber. Accordingly, tin-cure silicone rubbers are usually significantly less expensive than platinum-cure ones.
All mold making rubbers may be subject to cure inhibition by contaminants on the surface of a model being used for mold making. Silicone rubber is sensitive to sulfur that can be found on different surfaces and are present in some types of modeling clay. Platinum-cure silicone rubbers are critically sensitive to sulfur and will not cure under any circumstances when exposed. Tin-cure silicone can cure over models containing sulfur if the model surface is first thoroughly sealed with an acrylic spray.
A major difference between these two systems is shrinkage of the cured rubber over the short and long term. Tin-cure silicone rubber molds generally exhibit higher shrinkage over time depending on the type of mold rubber being used, material being cast into the rubber mold, mold configuration, and other variables.
Tin-cure silicone rubber molds have a limited library life. Depending on the specific tin-cure silicone, the library life of a rubber mold can be as little as 6-8 months, which may be acceptable if your project is short term.
Platinum-cure silicone has a relatively long library life that is measured in decades. Museums choose platinum-cure silicone rubbers to make molds of valuable artifacts and works of art.
Which silicone rubber chemistry (tin vs. platinum) will give you the longest life for production casting of wax, gypsum, concrete, resin, etc.? It depends on different variables and is usually application specific to determine which rubber mold material is right for your project, contact us easily to find out which kind of silicone is suitable for your project.