Wacker Cenusil® M 825 A/B – Pourable Addition-Cure Silicone for Concrete Moulds & Reproduction Moulds

Premium Pourable Addition-Cure Silicone for Professional Concrete Moulds and Reproduction Moulds

Wacker CENUSIL® M 825 A/B is a pourable, addition-cure two-component silicone rubber that cures at room temperature to a white rubber with a Shore A hardness of 25 and excellent self-degassing properties. With a pot life of 60 minutes and a demoulding time of 6 hours at 23 °C, it gives you ample working time for complex moulds. The mix ratio is 1:1 (A:B) by weight — the simplest mixing in its class. CENUSIL M 825 is ideally suited to applications in which shrink-free curing, deep undercuts and excellent resistance to common reproduction materials are essential.

Key Benefits

• 1:1 mix ratio by weight: The simplest processing in its class — no weighing errors, ready to use without a calculator
• Excellent self-degassing: A low viscosity of 8,000 mPa·s and active self-degassing eliminate air bubbles without a vacuum pump
• Shrink-free curing: No chemical shrinkage — dimensionally accurate reproductions of complex models with deep undercuts
• High tear strength (20 N/mm): Moulds release easily without tearing, even around narrow cavities, holes and gaps
• Excellent long-term stability: Mechanical properties remain stable over many casting cycles — ideal for series production
• Resistant to common reproduction materials: Good resistance to casting resins, concrete, plaster and wax

Typical Applications

• Concrete moulds for architectural elements, facade panels and decorative concrete
• Reproduction moulds of models with deep undercuts and complex geometries
• Moulds for plaster casting, synthetic resin and restoration work in museums and heritage conservation
• Prototyping and series production in industrial design and engineering
• Moulds for decorative objects, relief panels and architectural ornaments
• Reproductions for the art sector and for scenic design in film and theatre

Processing instructions:

1. Stir Part A and Part B thoroughly, each separately, before use
2. Mix A and B in a 1:1 ratio by weight — only use components with the same lot number
3. Mix slowly and carefully in a figure-of-eight motion to minimise air entrapment
4. Optional: vacuum degas immediately after mixing (the material can still be processed up to 60,000 mPa·s)
5. Pour within the 60-minute pot life
6. Allow to cure for at least 6 hours at 23 °C — curing can be accelerated by raising the temperature

Wacker Chemie AG is a world market leader in the development and production of silicones for industrial and technical applications. The CENUSIL series has been developed specifically for reproduction and concrete mould applications in which dimensional accuracy and durability are paramount.

Important Warning: Inhibition of Addition-Cure Silicones

Please note: This is an addition-cure (platinum-cure) silicone. These silicones can be inhibited by sulphur, nitrogen, amino compounds and metal salts. If you are not sure whether the materials you use (gloves, spatulas, moulds) contain these substances, carry out a small test first. Inhibiting substances are found in latex gloves, some plasticines, condensation-cure silicones, one-component silicone sealants and certain 3D printing materials, among others. If in doubt, apply a coat of polyvinyl alcohol (PVA) as a barrier layer.

Professional Support

Our technical specialists can advise you on processing techniques, optimising your mould design, accelerating cure and the right choice for your specific concrete mould or reproduction mould application. Contact us for technical data sheets, processing guides or product advice.