Wacker ELASTOSIL® M 4503 – Pourable Condensation Silicone for Polyester Molds & Reproduction

Pourable Condensation Silicone for Cost-Effective Molds, Especially for Polyester Resin

Wacker ELASTOSIL® M 4503 is a pourable, condensation-curing two-component silicone rubber (RTV-2) that cures at room temperature. With a Shore A hardness of 25, a tear strength of more than 20 N/mm and an elongation at break of 350%, this material is particularly suitable for molds of models with pronounced undercuts. Its high resistance to casting resins, especially polyester, ensures a long mold life. ELASTOSIL® M 4503 is processed with 2 wt% WACKER® Catalyst T 40; the catalyst is supplied separately.

Key Benefits

• High resistance to polyester resin: suitable for repeated casting of polyester resin, as well as plaster and wax.
• Tear strength >20 N/mm: molds of heavily undercut models can be demolded without tearing.
• Elongation at break 350%: high extensibility and elasticity for demolding complex geometries.
• Shore A 25: soft and flexible, with long-term stable mechanical properties.
• Good flow: pourable with a viscosity of approx. 40,000 mPa·s, good detail reproduction.
• Adjustable working time: with 2–4% Catalyst T 40 you can adapt pot life and cure time to your application.
• No inhibition issues: as a condensation silicone it is insensitive to the substances that can inhibit addition silicones.

Typical Applications

• Cost-effective molds for casting polyester resin
• Reproduction of models with very pronounced undercuts
• Molds for plaster and wax casting
• Reproduction of sculptures, reliefs and decorative objects
• Model making and prototyping

Processing instructions:

1. Stir the base (white) thoroughly in its container before use, so that any settled fillers are evenly redistributed.
2. Weigh out the required amount and add 2 wt% WACKER® Catalyst T 40 (20 g per kg). For faster processing and curing, up to 4% can be added.
3. Mix slowly and carefully until the mixture is homogeneous and streak-free, scraping the sides and bottom of the mixing cup.
4. Optionally degas the mixture in a vacuum chamber to remove air bubbles; recommended for fine details.
5. Pour the mixture slowly from a single point into the mold within the pot life (approx. 75 minutes at 23 °C with 2% T 40).
6. The mold can be demolded after approx. 20 hours at 23 °C. Final properties are reached after approx. 7 days at 23 °C / 50% relative humidity.

Manufactured by Wacker Chemie AG in Munich, Germany.

Note: Condensation Silicone

ELASTOSIL® M 4503 is a condensation-curing silicone. Allow for a linear shrinkage of approx. 0.5%; for dimension-critical applications an addition silicone such as ELASTOSIL® M 4601 A/B is more suitable. This product is not suitable for food contact. Curing takes place with the help of air humidity: in very dry conditions or thick layers, curing may take longer.

Professional Support

Not sure which silicone best suits your casting resin or application? Contact us for technical data sheets, processing advice or a quotation for larger quantities.