$ELASTOSIL<sup>®</sup> M 4370 A/B

Pourable, addition-curing, two-component silicone rubber that vulcanizes at room temperature.


Main application: Silicone surface for printing rollers, making molds for casting low-melting metal alloys.


Food contact (FDA/ BfR compliant).


  • Very good flowability and self-deaeration
  • Fast and non-shrink cure at room temperature which can be accelerated considerably by the application of heat
  • High hardness (Shore A approx. 55)
  • Very good heat resistance
  • Outstanding resistance to common casting resins

Specific features of ELASTOSIL® M 4370 A/B

  • Addition Curing
  • BfR compliant
  • FDA compliant
  • Flowable
  • Heat resistant
  • Low viscosity
  • Resistance against casting resins
  • Resistance against low melting metals and metal alloys
  • Two-component

Being an addition-curing and thus a non-shrink vulcanizing rubber with high hardness, ELASTOSIL® M 4370 A/B is particularly suitable for molding applications in which high elongation and tear resistance can be sacrificed in favor of excellent deformation resistance and thermal stability, e. g., for making molds of models with nor or only minor undercuts if, in addition to absolute accuracy of reproduction, good heat dissipation and high rigidity are required.

Typical applications are molds with

  • high rigidity for foaming resins
  • high swelling resistance to components of casting resins, such as styrene in the case of polyesters
  • high thermal stability and heat dissipation for casting low-melting metal alloys

Important note: The platinum catalyst is in component A.

Important: A and B components may only be used together if they have the same batch number.

Thin-walled molds are best suited for casting low-melting metal alloys (melting point: 300 °C max.) and should be placed on a sheet of aluminum or other material with high thermal conductivity. Before the casting process, the old should be post-cured for a few hours at about 150 °C. In order to improve wetting by the molten metal, a thin layer of extremely fine silicon carbide, graphite powder or acetylene black should be applied to the mold surface. The first castings have normally to be discarded since the rubber still emits gases, giving the surface of the casting a pockmarked appearance.

Comprehensive instructions are given in our leaflet "ROOM TEMPERATURE VULCANIZING (RTV) SILICONES".

Detailed information on other mold-making compounds in the ELASTOSIL ® M range is contained in our brochure "MOLDMAKING: FORM HAS NO LIMITS".


The 'Best use before end' date of each batch is shown on the product label. Storage beyond the date specified on the label does not necessarily mean that the product is no longer usable. In this case however, the properties required for the intended use must be checked for quality assurance reasons.

Sales and support

Wacker Chemical Corporation
3301 Sutton Road
Adrian, MI 49221-9397
United States
+1  888  922-5374 (Phone)

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