Premium Pourable Addition Curing Silicone for Professional Mold Making and Encapsulation Applications

Wacker ELASTOSIL® RT 625 A/B is a pourable, addition-curing 2-component silicone rubber that cures at room temperature with a Shore A hardness of 25, fully translucent end product, and excellent mechanical properties. With a pot life of 60 minutes and a curing time of 12 hours at 20°C, this product offers ample processing time for complex molds without time pressure. The mixing ratio is 9:1 (A:B) by weight, with the platinum catalyst in component B. ELASTOSIL RT 625 is ideally suited for applications where low viscosity, high tear strength, and shrink-free curing are essential.

Key Benefits

• Low viscosity (12,000 mPa·s): Flows effortlessly into complex shapes and narrow cavities without air bubbles – ideal for detailed molds
• Shrink-free curing: Linear shrinkage < 0.1% for dimensionally accurate reproductions and repeated casting
• Excellent tear strength (30 N/mm): Molds release easily without tearing, even with complex undercuts
• High elongation (600%): Particularly flexible and robust when demolding molds with fine details
• Curing in closed systems: Addition curing does not require atmospheric moisture – suitable for encapsulation
• Food-safe application: Complies with EC 1935/2004 for food contact materials provided the final product meets the specified migration limits

Typical Applications

• Mold making for casting polyurethane, epoxy, plaster, and acrylic resin in art, design, and prototyping
• Encapsulation of electrical and electronic components for protection and electrical insulation
• Coatings and protective layers for technical parts and delicate objects
• Reproduction of molds for vacuum bags in composite processing
• Production of technical cast parts in small and medium series
• Culinary applications such as silicone bakeware and food contact items

Processing Instructions:

1. Stir components A and B thoroughly and separately before use
2. Mix A and B in a 9:1 weight ratio — use only components with the same batch number
3. Mix slowly and carefully to minimize air entrapment
4. Optional: vacuum immediately after mixing to remove residual air bubbles
5. Pour within the 60-minute pot life
6. Allow to cure for 12 hours at 20°C — accelerated curing is possible by increasing the temperature

Wacker Chemie AG is a global market leader in the development and production of silicones for industrial and technical applications. The ELASTOSIL series is known for consistent quality and reliable technical specifications.

Important Warning: Inhibition in Addition-Curing Silicones

Please note: This is an addition-curing silicone (platinum-cure). These silicones can be inhibited by sulfur, nitrogen, amino compounds, and metal salts. If you are unsure whether the materials you are using (gloves, spatulas, molds) contain these substances, first do a small test. Inhibiting substances can be found in latex gloves, some plasticines, condensation-ccuring silicones, 1-component silicone sealant, and certain 3D printing materials. If in doubt, apply a layer of polyvinyl alcohol (PVA) as a release agent.

Professional Support

Our technical specialists advise on processing techniques, vacuum degassing, curing acceleration, and the right choice for your specific mold-making, encapsulation, or coating application. Contact us for technical datasheets, processing manuals, or product advice.