Premium Heat-Resistant Addition Silicone for Professional Reproduction and Metal Casting Applications

Elastosil® M 4370 A/B is a pourable, addition-curing two-component silicone rubber (RTV-2) that cures shrink-free at room temperature and can be significantly accelerated by heat. With a Shore A hardness of 55, a red-brown final color, and excellent thermal conductivity of 0.55 W/mK, this is a dimensionally stable, heat-resistant silicone. The pot life is approximately 80 minutes, and it cures tack-free in about 6 hours, with a mixing ratio of 9:1 (A:B) by weight. This silicone is ideally suited for reproduction molds where dimensional stability and heat dissipation are more important than high elongation and tear strength.

Key Benefits

• Hardness Shore A 55 – high dimensional stability for pressure-stable molds.
• Linear shrinkage < 0.1% – dimensionally accurate reproduction without post-processing.
• Thermal conductivity 0.55 W/mK – rapid heat dissipation when casting low-melting metal alloys up to 300 °C.
• Mixing viscosity 8000 mPa·s – good flowability and self-deaeration for detailed castings.
• Pot life approximately 80 minutes – ample processing time, can be accelerated by heat.
• Resistance to casting resins – excellent resistance to polyester, polyurethane, and epoxy.

Typical Applications

• Molds for casting low-melting metal alloys (melting point maximum 300 °C).
• Pressure-stable molds for foaming resins.
• Reproduction molds for polyester resin with high styrene resistance.
• Coating of printing rollers.
• Forming of models with few to no undercuts where dimensional stability is paramount.
• Food contact applications in accordance with FDA and BfR.

Processing

1. Stir components A and B separately thoroughly in their packaging; for component A, this evenly distributes the pigments.
2. Mix A and B in a 9:1 weight ratio. Note: use only A and B components with the same lot number (batch number).
3. Mix slowly and thoroughly, scraping the bottom and sides of the mixing container to achieve a completely homogeneous mixture.
4. If desired, deaerate the mixture under vacuum (10–20 mbar) to prevent air inclusions.
5. Pour within the pot life of approximately 80 minutes in a thin stream from a low height.
6. Allow to cure for approximately 6 hours at room temperature; heat significantly accelerates this. For metal casting, the mold can be tempered for several hours at approximately 150 °C.

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

Note on Addition Silicones (Inhibition)

Addition-curing silicones can be inhibited by certain substances. Avoid contact with sulfur and sulfur-containing materials (such as certain rubbers and EPDM), amines and amine-cured epoxy resins, tin and other organometallic compounds, and condensation silicones. If you are unsure about a substrate, perform a small test casting beforehand to check for complete curing.

Professional Support

Do you need advice on the right silicone for metal casting, printing rollers, or heat-resistant reproduction molds? This product is intended for the business market. For larger quantities or custom solutions, please contact us at info@nedform.com or +31 (0)46-3030989.