TinSil® rubbers are tin catalyzed (or condensation cured) silicone rubbers. Tin silicones shrink slightly upon cure, and finished molds do not have a great library life compared to some other chemistries. PlatSil® rubbers are platinum cured (or addition cured) silicone rubbers. Platinum molds do not shrink upon cure, and finished molds have a better shelf life than tin-cured silicones. Tin silicones are less expensive. Platinum silicones are more susceptible to chemical inhibition, so they often require a test cure before use. (Note: If you use a Tin silicone on a surface, you can no longer pour a platinum silicone against the same master due to inhibition issues. You can, however, pour a tin silicone after using a platinum silicone.)
FACTORS TO CONSIDER WHEN SELECTING A SILICONE
| Tin-Cured TinSil® Silicones | Platinum-Cured PlatSil® Silicones | |
| Excellent Release Properties | x | x |
| Less Sensitive to Cure Inhibition* | x | |
| Longer Storage Life of Finished Mold/Part | x | |
| No Shrink Upon Cure | ~1% | x |
| Lower Cost | x |
*Cure inhibition is the failure of a compound to cure against a surface within the recommended cure time. The surface in contact with the pattern remains gummy or uncured. Inhibition is most likely to occur platinum-cured (addition-cured) silicone systems.