Premium Transparent Addition Silicone for Professional Prototyping and Mold Making Applications

Elastosil® M 4644 A/B is a pourable, addition-curing (platinum-cure) two-component silicone rubber that vulcanizes at room temperature and can be significantly accelerated with heat. The silicone has a medium hardness of Shore A 40, good transparency of the cured rubber, and cures without shrinkage (linear shrinkage ≤ 0.1%). With a mixing ratio of 10:1 by weight, a mixing viscosity of approximately 50,000 mPa·s, and a pot life of about 80 minutes, this material offers ample processing time, with tack-free curing after approximately 12 hours at 23 °C. The silicone lightly exudes oil, which promotes demolding, and is excellently resistant to casting resins such as polyurethane and epoxy, ensuring a very long mold life. Its core application is vacuum casting for rapid prototyping.

Key Benefits

• Shore A hardness 40 – medium hardness that combines dimensional stability with sufficient flexibility to demold models with undercuts.
• Tear strength > 25 N/mm – high tear resistance for molds that need to withstand many demolding cycles.
• Tensile strength 5.5 N/mm² – robust mechanical properties for a long mold service life.
• Elongation at break 400% – ample elongation for demolding complex geometries without tearing.
• Linear shrinkage ≤ 0.1% – shrinkage-free curing for dimensionally stable castings and accurate reproduction.
• Mixing viscosity 50,000 mPa·s – good flowing mixture that accurately reproduces details and undercuts.

Typical Applications

• Vacuum casting for rapid prototyping of polyurethane and epoxy parts.
• Production molds for casting resins with a long service life.
• Reproduction of models with fine details and undercuts.
• Prototype construction in industrial design and product development.
• Molds for small series in polyurethane and epoxy systems.

Processing Instructions

1. Stir component A and component B thoroughly separately first.
2. Mix component A and B in a weight ratio of 10:1. Use A and B only together if they have the same batch number.
3. Mix slowly and thoroughly (figure-8 motion or mechanically at low speed) until a homogeneous, streak-free mixture is achieved.
4. Preferably degas the mixture under vacuum to remove air inclusions.
5. Pour the mixture within the pot life of approximately 80 minutes.
6. Allow to cure for approximately 12 hours at 23 °C. Curing can be significantly accelerated with heat.

Note for Addition Silicones

Addition-curing (platinum-cure) silicones are sensitive to inhibition. Substances such as condensation silicones, sulfur-containing clays, latex, tin, and amine-containing compounds can slow down or prevent curing. If in doubt, always test on a small area first before pouring the entire model.

About the Manufacturer

Wacker Chemie AG is a global market leader in the development and production of silicones for industrial and technical applications.

Professional Support

For advice on vacuum casting and mold making with Elastosil® M 4644 A/B, our specialists are happy to assist you. This product is intended for the business market. For larger quantities or custom products, please contact us via info@nedform.com or +31 (0)46-3030989.