Wacker Elastosil M 4514® Part A – Condensation Silicone Base for Moulds & Reproduction Casting

Premium pourable condensation-cure silicone base for professional mould-making and reproduction applications

Elastosil M 4514 (Part A) is the base component of a pourable, condensation-cure (tin-cure) RTV-2 silicone rubber that vulcanises at room temperature. This white, paste-like base has a dynamic viscosity of approximately 35,000 mPa·s and a density of 1.26 g/cm³ (uncured). Once cured, it forms a white, flexible mould with a Shore A hardness of approximately 25, a tensile strength of 4.5 N/mm², an elongation at break of 450%, a tear strength of 18 to 25 N/mm and a linear shrinkage of less than 0.4%. The material is known for its very good flow and self-degassing properties and for its excellent chemical resistance to polyester and polyurethane resins, which considerably extends the service life of the mould.

Please note: this is Part A only. To process it, you need a curing agent (Part B). For polyester resins, plaster, concrete, cast stone and wax, choose Catalyst T 51 (5%); for epoxy and polyurethane resins, choose Catalyst T 21 (5%). Pot life and demoulding time depend on the curing agent chosen; with 5% T 51 they are typically 60 to 90 minutes (pot life) and 8 to 12 hours (demoulding time).

Key Benefits

• Shore A hardness 25 (cured) – a flexible mould that demoulds easily and without damage, even with deep undercuts.
• Tear strength 18 to 25 N/mm – very high resistance to tear initiation and tear propagation for a long mould life.
• Tensile strength 4.5 N/mm² and elongation at break 450% – high elasticity, so the mould can be stretched considerably without damage.
• Base viscosity 35,000 mPa·s – very good flow and self-degassing for a bubble-free cast.
• Linear shrinkage < 0.4% (cured) – accurate dimensional stability for reproductions true to every detail.
• Excellent resin resistance (polyester and polyurethane) – a high number of casts per mould, even with aggressive casting resins.

Typical Applications

• Base for moulds for casting polyester and polyurethane resins.
• Reproduction of sculptures, ornaments and restoration objects with pronounced undercuts.
• Moulds for plaster, concrete and cast stone, such as facade elements and tiles.
• Moulds for wax, candles and the lost-wax casting process.
• Moulds for low-melting metal alloys.
• Block and skin moulds, one-piece or multi-part, using pouring, impression or brush-on techniques.

Processing Instructions

1. Choose the right curing agent: Catalyst T 51 for polyester, plaster, concrete, cast stone and wax; Catalyst T 21 for epoxy and polyurethane resins.
2. Stir Part A thoroughly before use to redistribute any settled material.
3. Weigh out in a weight ratio of 100:5 (5 grams of curing agent per 100 grams of Part A). Less curing agent extends pot life and demoulding time; more curing agent speeds up curing but increases shrinkage. Never use too little curing agent, or the silicone will not cure (properly).
4. Mix A and B carefully and evenly, scraping the sides and bottom of the mixing container thoroughly.
5. Preferably degas the mixture under vacuum (10–20 mbar) and pour it within the pot life in a thin stream from a low height.
6. Allow to cure at room temperature (> 40% relative humidity) before demoulding; the exact time depends on the curing agent chosen.

Faster curing: the curing agent T 51 or T 21 can be blended with Catalyst T 47. At 95:5 (T 51 : T 47), the pot life drops to approximately 30 minutes and the mould can be demoulded after approximately 4 hours.

Please note: pot life and demoulding time depend strongly on the mix ratio and the humidity. With more curing agent or higher humidity, both become shorter. Below 40% relative humidity, the surface may remain tacky; in that case, increase the humidity in the room.

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

We also offer the standard combination of Elastosil M 4514 with Catalyst T 51 as a ready-to-use set.

This product is intended for the business market. For larger quantities or custom products, please contact us at info@siliconesandmore.com.

Professional Support

Not sure which curing agent suits your application? Our specialists will be happy to advise you on the right choice of curing agent and mix ratio. Please do not hesitate to contact us.