Wacker Elastosil® M 4370 A/B – Red-Brown Addition-Cure Silicone for Reproduction Moulds & Metal Casting
Wacker Elastosil® M 4370 A/B – Red-Brown Addition-Cure Silicone for Reproduction Moulds & Metal Casting
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Variant: 1 kg. Set (0.9 A + 0.1 B) B2B
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Premium Heat-Resistant Addition-Cure Silicone for Professional Reproduction and Metal Casting Applications
Elastosil® M 4370 A/B is a pourable, addition-cure two-component silicone rubber (RTV-2) that vulcanises shrink-free at room temperature; cure can be greatly accelerated by heat. With a hardness of Shore A 55, a red-brown final colour and excellent thermal conductivity of 0.55 W/mK, it is a dimensionally stable, heat-resistant silicone. The pot life is approx. 80 minutes and the rubber is tack-free after about 6 hours, at a mix ratio of 9:1 (A:B) by weight. The silicone is ideally suited to reproduction moulds in which dimensional stability and heat dissipation matter more than high elongation and tear strength.
Key Benefits
- Hardness Shore A 55 – high dimensional stability for pressure-resistant moulds.
- Linear shrinkage < 0.1% – dimensionally accurate reproduction without finishing.
- Thermal conductivity 0.55 W/mK – rapid heat dissipation when casting low-melting metal alloys up to 300 °C.
- Mixed viscosity 8000 mPa·s – good flow and self-degassing for highly detailed casts.
- Pot life approx. 80 minutes – ample working time; cure can be accelerated with heat.
- Resistance to casting resins – excellent resistance to polyester, polyurethane and epoxy.
Typical Applications
- Moulds for casting low-melting metal alloys (melting point up to 300 °C).
- Pressure-resistant moulds for foaming resins.
- Reproduction moulds for polyester resin with high styrene resistance.
- Coating of printing rollers.
- Moulding models with few or no undercuts where dimensional stability comes first.
- Food-contact applications: the Wacker TDS states BfR compliance. Please request the current Wacker declaration from us in advance.
Processing
- Stir Part A and Part B thoroughly, each in its own container; for Part A this distributes the pigments evenly.
- Mix A and B in a 9:1 ratio by weight. Note: only use A and B components with the same lot number (batch number).
- Mix slowly and thoroughly, scraping the bottom and sides of the mixing container to achieve a completely homogeneous mix.
- If required, degas the mixture under vacuum (10–20 mbar) to prevent air entrapment.
- Within the pot life of approx. 80 minutes, pour in a thin stream from a low height.
- Allow to cure for approx. 6 hours at room temperature; heat speeds this up considerably. For metal casting, the mould can be post-cured for a few hours at approx. 150 °C.
Wacker Chemie AG is a world market leader in the development and production of silicones for industrial and technical applications.
Please Note with Addition-Cure Silicones (Inhibition)
Addition-cure silicones can be inhibited by certain substances. Avoid contact with sulphur and sulphur-containing materials (such as certain rubbers and EPDM), amines and amine-cured epoxy resins, tin and other organometallic compounds, and condensation-cure silicones. If you are unsure about a substrate, carry out a small test cast beforehand to check that it cures fully.
Professional Support
Do you need advice on the right silicone for metal casting, printing rollers or heat-resistant reproduction moulds? This product is intended for the business market. For larger quantities or custom requirements, please contact us at info@siliconesandmore.com.
Product Properties
- Hardness55Shore AHardness of the silicone material
- Shrinkage0.1%Linear shrinkage after curing
- ColorReddish brownColor of the finished product
- TransparencyOpaqueDegree of transparency
- Viscosity8000mPa·sViscosity of the uncured silicone
- Density1.43g/cm³Density of the cured material
- Mix ratio9:1Mixing ratio A : B
- Tensile strength3.0MPaMaximum tensile force before breaking
- Tear strength4.0kN/mResistance against tearing
- Elongation at break130%Maximum stretch before breaking
- Pot life80minutesWorking time after mixing
- Cure time360minutesTime until full cure
Component Properties
- Color AReddish-brownColor of component A
- Color BColorlessColor of component B
- Viscosity A10000mPa·sViscosity of component A
- Viscosity B350mPa·sViscosity of component B
- Density A1.5g/cm³Density of component A
- Density B1.05g/cm³Density of component B
Thermal Properties
- Thermal conductivity0.55W/m·KHow well heat is transferred
Certification & Safety
- Food-gradeYesSuitable for food contact
- Chemical resistanceExcellent resistance to common casting resins (polyester, polyurethane, epoxy) and to low-melting metal alloys with a melting point up to 300 °C on short contactResistance to chemicals
Application
- Use caseReproduction moulds for metal casting and casting resinsIntended use
- Silicone type["Addition cure","RTV-2"]Type of silicone or polymer
- Cure speedNormalHow quickly the material can be demoulded
- Cure conditionRoom temperature or heatCondition under which the material cures
Safety Information
According to Regulation (EC) 1272/2008, ELASTOSIL M 4370 A and B are not classified as hazardous substances or mixtures and do not carry a hazard pictogram. Component A contains bound quartz in the liquid matrix; the dust inhalation hazard is not applicable under normal use as the filler is not released in respirable form. In contact with water, alcohols, acids, or bases, component B can form hydrogen gas; therefore, keep the product away from these substances and ensure good ventilation. When processing, wear protective gloves made of nitrile rubber or butyl rubber and safety glasses according to EN 166. In case of mist or spray formation, respiratory protection with an FFP1 filter is recommended. Observe general hygiene measures, do not eat, drink, or smoke during work, and wash hands after use. For complete information, always consult the safety data sheet of the respective component.| Safety Pictograms | Safety Data Sheets (SDS) |
|---|---|
Required protection (ISO 7010)
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Frequently asked questions
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Indicative delivery times: Netherlands usually within 1 working day, Belgium and Germany typically 1–2 working days, other countries depending on destination and carrier. These are guidelines, not guarantees: peak periods, public holidays or carrier delays can have an effect.
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