Difference Between Tin-Cure and Platinum-Cure Silicone Rubber Mold Making

Difference Between Tin-Cure and Platinum-Cure Silicone Rubber Mold Making

Two-component room temperature vulcanization mold making silicone rubber is divided into two categories of tin-cure (condensation cure) and platinum-cure (addition cure), many silicone users do not know which to choose, then what is the difference between these two silicone? The following will give you a comprehensive analysis of the difference between condensation and addition cure mold making silicone rubber.


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.


Performance Differences
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.

Library Life
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 12 months, which may be acceptable if your project is short term.  At the end of a rubber mold's library life, the mold will tear easily and become unusable. 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.

Production Life
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, PLEASE CONTACT US.



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