Learn All About Silicone Rubber
A complete guide to understanding silicone rubber, its chemistry, properties, applications, and how to choose the right type for your project. This page covers both Tin-Cure and Platinum-Cure silicones in detail, with side-by-side comparisons and real-world use cases.
1. Introduction to Silicone Rubber
Silicone rubber is one of the most adaptable and high-performance materials available today. From industrial gaskets to custom chocolate molds, its ability to retain flexibility, resist extreme temperatures, and deliver fine detail makes it an essential material across multiple industries. It is synthetic, derived from silica (sand), and can be formulated to meet the exact demands of the application.
Unlike natural rubber, silicone is not affected by ozone, UV radiation, or weathering — making it ideal for both indoor and outdoor use. It can also be made food-safe (especially Platinum-Cure) and skin-safe, enabling its use in medical and culinary applications.
2. The Chemistry of Silicone Rubber
The base polymer in silicone rubber is made up of repeating siloxane bonds (Si–O–Si), giving it outstanding thermal stability and flexibility. The curing method determines its category:
- Tin-Cure (Condensation Cure): Uses organotin salts as catalysts. Releases byproducts (usually alcohol) during curing, leading to minimal shrinkage.
- Platinum-Cure (Addition Cure): Uses platinum-based catalysts. No byproducts are released, resulting in virtually zero shrinkage and high dimensional accuracy.
Note: The choice between Tin-Cure and Platinum-Cure depends on cost, project lifespan, food safety requirements, and the type of casting material.
3. Tin-Cure vs Platinum-Cure Silicone — Detailed Side-by-Side Comparison
| Feature | Tin-Cure Silicone | Platinum-Cure Silicone |
|---|---|---|
| Curing Type | Condensation cure — releases alcohol | Addition cure — no byproducts |
| Mix Ratio | 100:2 (Base to Catalyst) | Typically 1:1 by weight or volume |
| Shrinkage | Up to 0.6% | Virtually 0% |
| Food Safety | Not food-safe | Food-safe if certified |
| Tear Strength | Good | Excellent |
| Shelf Life | 6–12 months | 12–18 months |
| Cost | Lower | Higher |
4. 30 Common Uses — Side-by-Side
| Tin-Cure Silicone — Common Uses | Platinum-Cure Silicone — Common Uses |
|---|---|
| Concrete casting molds | Food molds (chocolates, fondant, gummies) |
| Plaster/Gypsum molds | Medical prosthetics |
| Wax candle molds | Special effects makeup appliances |
| Decorative stone molds | Dental impressions |
| Low-volume resin casting | Long-life resin molds |
| Costume props | Skin-safe wearable props |
| Polyurethane foam molds | Jewelry casting molds |
| Architectural restoration | Museum artifact replication |
| Rapid prototyping molds | Cleanroom sealing parts |
| Temporary outdoor moldings | Aquarium-safe seals |
| Crafts and hobby molds | Baby-safe toys (with certification) |
| Film & theater set details | Microfluidic device prototyping |
| Temporary tool grips | Underwater sealing gaskets |
| Prototype art sculptures | Permanent architectural moldings |
| Simple keychains and souvenirs | High-precision industrial molds |
5. Key Properties of Silicone Rubber
Silicone rubber’s properties make it irreplaceable in many settings. These include:
- Wide temperature tolerance (-50°C to +200°C)
- Elasticity retained over time
- UV and ozone resistance
- Chemical inertness
- Water resistance
- Electrical insulation
- Ease of coloring and pigmentation
6. Real-World Applications by Industry
Construction
- Sealants and gaskets
- Concrete form liners
- Roofing accessories
Arts & Crafts
- Decorative mold-making
- Soap and candle molds
- Custom figurines
Medical
- Prosthetic components
- Medical tubing
- Orthopedic supports
7. Frequently Asked Questions
How long do silicone molds last?
Platinum-cure molds can last for hundreds of casts if maintained properly, while tin-cure molds may degrade faster. Can I color silicone?
Yes, with silicone-compatible pigments. Which is better for chocolate molds?
Platinum-cure silicone, as it can be food-safe.
Need help choosing? Contact Rubber Inc to get expert guidance on the best silicone rubber for your project.