Premium Shrink-Free Addition-Cure Silicone for Professional Reproduction and Prototyping Applications
Elastosil M 4670 A/B is a pourable, addition-curing (platinum-cure) two-component RTV-2 silicone that cures shrink-free at room temperature and can be accelerated by heat. The cured rubber has a high hardness of Shore A 55 and a beige final color. The major strength of this silicone is its excellent resistance to casting resins combined with a high tear strength, which ensures molds with a long service life and dimensionally stable self-stability. With a pot life of 90 minutes, a curing time of 12 hours at 23°C, and a mixing ratio of 10 to 1 by weight, the material is suitable for the shrink-free and dimensionally stable molding of models with undercuts. When processed appropriately, the raw material is suitable for the manufacture of food contact materials under Regulation (EC) 1935/2004, subject to the conditions set out in the Food Contact and Regulations section.
This product is intended for the business market. For larger quantities or custom products, you can contact us at info@siliconesandmore.com.
Key Benefits
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Hardness Shore A 55, relatively hard, dimensionally stable mold with good self-stability for models with undercuts
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Tear strength 15 N/mm, high resistance to tearing ensures a long service life of the mold
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Linear shrinkage < 0.1%, dimensionally stable, shrink-free molding with excellent reproduction accuracy
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Tensile strength 5.5 N/mm², strong vulcanizate with stable long-term mechanical properties
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Pot life 90 minutes, ample processing time at 23°C for larger or complex moldings
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Raw material compliant with Regulation (EC) 1935/2004, suitable when processed appropriately for the manufacture of food contact materials, with conformity of the finished article resting with its manufacturer
Typical Applications
- Reproduction molds for casting resins such as polyurethane, epoxy, and polyester
- Composite molding in the automotive, marine construction, and wind turbine industries
- Prototyping of models with undercuts
- Precast concrete and wet cast in the construction industry
- Culinary molds and molds for food contact, provided the finished article is demonstrably made compliant
- Props, set building, and design
Processing
- First stir the A-component and B-component thoroughly and separately.
- Mix the components in the weight ratio of 10 parts A to 1 part B. Note: use only A- and B-components with the same lot number.
- Mix slowly in a figure-8 motion without beating in air until a homogeneous mixture is obtained.
- Preferably degas the mixture under vacuum to remove air bubbles.
- Pour the mixture within the pot life of 90 minutes.
- Allow to cure for 12 hours at 23°C. The curing process can be accelerated in an oven; bear in mind that air bubbles then have less time to escape. We recommend post-baking the mold for 2 to 3 hours at 100°C after demolding for complete degassing.
Note: pot life and demold time are strongly dependent on the temperature. At a higher temperature, the processing time and demold time become shorter.
Wacker Chemie AG is the world market leader in the development and production of silicones for industrial and technical applications.
⚠️ Note: this is an addition-cure silicone (platinum-cure). These silicones can be poisoned (inhibited) by sulfur, nitrogen, amino compounds, and metal salts. If you are not sure whether the products you use (including gloves, spatulas, and cups) contain these ingredients, do a small test first. These substances occur, among others, in many latex gloves, some plasticines, varnishes and adhesives, condensation silicones, 1-component silicone sealant, natural rubbers, and 3D printing material (especially stereolithography). If you still want to use these, apply a protective layer of polyvinyl alcohol.
Food Contact and Regulations
⚠️ Most critical condition of use: residual toluene. The product contains small amounts of residual toluene. These must be completely removed from the finished food contact article, for example by full post-curing and degassing, before the mold may come into contact with food. Without this step, the finished mold is not suitable for food contact.
The data below is taken from the Wacker Regulatory Product Information for Elastosil M 4670 A/B, version 1.13, last modified 05-05-2026. It relates to the raw material, not to your finished mold.
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Regulation (EC) 1935/2004, suitable when processed appropriately for the manufacture of food contact materials and articles. Conformity of the finished article, including its suitability for the intended use, compliance with the stated restrictions, and the effect on taste and odor, must be ensured by the producer of that finished article.
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Regulation (EU) 10/2011, not applicable, silicones are excluded.
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Regulation (EC) 2023/2006, not applicable, this is a starting material.
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Germany, BfR Recommendation XV Silicones, ingredients compliant, with a restriction for the cured elastomer of max. 0.5 % volatiles.
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France, Arrêté of 25 November 1992, compliant, overall migration from the finished article max. 10 mg/dm² or 60 mg/kg, volatiles max. 0.5 %.
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Spain, Real Decreto 847 of July 2011, compliant, overall migration max. 10 mg/dm² or 60 mg/kg.
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Switzerland, Ordinance SR 817.023.21, ingredients listed in Annex 9.
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United States, a food contact statement can be provided separately upon request.
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China, GB 9685-2016, additives listed in table A.3 or A.7, with the platinum catalyst regarded as NIAS with a migration limit of 0.01 mg/kg food or simulant. GB 4806.16-2025, siloxane starting substances listed in table A.1. GB 4806.1-2016, complies.
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Brazil and Mercosur, base polymers compliant with the positive list under RDC 123 of 19 June 2001, base polymers and fillers listed in RDC 56 of 2012 and amendments, GMC RES 02/2012 and/or GMC RES 34/25. Overall migration from the finished article max. 8 mg/dm² or 50 mg/kg food.
The admissibility of the ingredients does not mean that the end product is considered safe for food contact by regulatory authorities. Responsibility for the finished article and for migration, extraction, and volatiles testing lies with the manufacturer of that end product. Consult the safety data sheet and the Regulatory Product Information for the full conditions.
Professional Support
Do you need advice on the right silicone for your reproduction or molds for casting resins? Silicones and More is happy to help. Contact us for personal advice, technical support, or a custom quote.
