Key takeaways
- Platinum cure is an addition reaction with no by-products, low shrinkage and food/medical safety.
- Tin cure is a condensation reaction — lower cost and forgiving, but higher shrinkage and shorter life.
- Platinum resins are cure-inhibited by sulfur, tin, amines and some plastics; tin is more tolerant.
- Pick platinum for precision, safety and reusable molds; tin for budget one-off or large casts.
Two curing chemistries dominate room- and heat-cure silicone: platinum (addition) cure and tin (condensation) cure. They look similar in the bucket but diverge sharply in accuracy, safety, durability and cost — so the right choice depends entirely on your application.
How each system cures
Platinum silicone cures by an addition reaction catalyzed by platinum: vinyl and hydride groups cross-link with no by-product, giving very low shrinkage (typically ≤0.1%). Tin silicone cures by a condensation reaction that releases a small alcohol by-product, causing more shrinkage (often 0.3–1%) and gradual property drift as the by-product leaves.
Head-to-head comparison
- Accuracy: platinum holds dimensions and fine detail; tin shrinks more and softens over time.
- Safety: platinum grades reach FDA / food / skin-contact compliance; tin is generally not for body contact.
- Durability / library life: platinum molds last for years; tin molds degrade and become brittle sooner.
- Cost: tin is cheaper and more forgiving to mix; platinum costs more but performs longer.
- Cure inhibition: platinum is sensitive to sulfur, tin, amines, latex and some plastics/clays; tin is far more tolerant of contamination.
Send us your part, tolerance and contact requirements — our engineers will recommend the right system.
When to choose platinum cure
Choose platinum for precision parts, medical and food-contact products, optically clear items, and reusable production molds where dimensional stability and long life justify the cost.
When to choose tin cure
Choose tin for budget-sensitive work, large one-off casts, or when the working surface may contain contaminants that would poison a platinum cure. It's forgiving and economical for non-contact, shorter-life applications.
Conclusion
Platinum and tin cures are complementary tools. If you need accuracy, safety and longevity, platinum LSR/HCR is the answer; if you need low cost and contamination tolerance for shorter-life parts, tin condensation silicone fits. Ruihe supplies both, with platinum grades certified for the most demanding markets.
