Premium Two-Component Primer for Professional Adhesion on Metal and Wood Applications

Wacker Primer AV is a two-component primer (mixing ratio 2:1 by weight) that promotes adhesion between silicone rubber and metal, aluminium or wood. The primer is colourless to light yellow, has a low solvent content and is specifically formulated for addition-cure (platinum-cure) RTV-2 silicones from, among others, the ELASTOSIL M and RT ranges. After mixing, the primer forms a rigid silicone resin film with which the catalysed silicone rubber forms a strong chemical bond during curing. Even silicone formulations with a high silicone fluid content, such as those used for printing pads, achieve excellent adhesion to aluminium or plywood carrier plates.

Key Benefits

• Mixing ratio 2:1 – components A and B are easily mixed by weight by shaking the closed mixing vessel.
• Pot life approximately 8 hours – ample working time; only mix the amount that can be processed within this period.
• Low solvent content – limited emission of volatile substances during processing.
• Reaction time from 15 minutes – the primer film reacts at a minimum of 40% relative humidity at ambient temperature.
• Excellent adhesion – also on silicone-fluid-modified rubbers and on smooth or porous substrates.
• Versatile – suitable for metal, aluminium, steel, lead, iron and wood.

Typical Applications

• Adhesion of addition-cure silicone rubber on aluminium carrier plates.
• Production of printing pads with silicone rubber on plywood or aluminium.
• Pre-treatment of metal parts embedded in silicone.
• Adhesion on wooden moulds and carrier structures.
• Industrial and technical applications requiring durable adhesion under stress.

Processing Instructions

1. Clean the substrate so that it is dry and free from grease, oil and contaminants. First clean with a non-polar solvent such as mineral spirits (boiling range 80 to 140 degrees Celsius), then with a polar solvent, preferably acetone.
2. Remove loose particles and roughen very smooth surfaces by grinding.
3. Mix components A and B in a 2:1 ratio by weight by shaking the closed mixing vessel. Never seal the mixing vessel gas-tight, as hydrogen gas may be released.
4. Only mix the amount that can be processed within the pot life of approximately 8 hours.
5. Apply the primer thinly and bubble-free with a brush, by dipping or spraying. On smooth, non-absorbent surfaces as thinly as possible; on rough or porous surfaces apply generously.
6. Allow the primer film to react for at least 15 minutes at a relative humidity of at least 40% (check with a hygrometer).
7. Apply the catalysed silicone rubber preferably directly after drying, but at the latest within 24 hours, as otherwise the adhesive strength may decrease.

Safety Information

Wacker Primer AV (component A) is highly flammable with a flash point of 2 degrees Celsius. Keep the product away from heat, sparks and open flame and work only in a well-ventilated area. Hydrogen gas may be released when mixing A and B; therefore never seal the mixing vessel gas-tight. Wear protective gloves, tight-fitting safety goggles and suitable protective clothing. Consult the full safety data sheet before use.

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

Professional Support

Not sure which primer and adhesion method suit your substrate and silicone type? The choice depends on the chemistry and surface properties of the substrate and sometimes requires a preliminary test. Contact us for tailored advice.