Wacker ELASTOSIL® AUX G 3243 – Primer for Silicone Rubber & Substrate Adhesion
Wacker ELASTOSIL® AUX G 3243 – Primer for Silicone Rubber & Substrate Adhesion
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Premium Adhesion-Promoting Primer for Professional Moulding and Encapsulation Applications
ELASTOSIL® AUX G 3243 is a solvent-based primer made from siloxanes and reactive silanes that serves as an adhesion promoter between substrate and vulcanised silicone rubber. The yellow, liquid primer has a density of 0.85 g/cm³ (23°C), a solids content of around 23% and a viscosity of 550 mm²/s. It pre-treats metal, ceramic, glass and various polymer surfaces so that solid ELASTOSIL® R silicone rubber (HCR/HTV, peroxide-curing) adheres durably to them. After the solvents evaporate, a rigid silicone resin film forms on exposure to atmospheric humidity, bonding firmly to a wide range of substrates. The primer can be applied undiluted or diluted up to 1:10 by coating, dipping, brushing or spraying, making it broadly suitable for moulding and encapsulation applications.
Key Benefits
- Broad substrate adhesion – bonds to metal, ceramic, glass and various polymers, enabling the bonding and encapsulation of diverse components.
- Thin working layer of 1–10 µm (5–50 g/m²) – a minimal layer thickness is enough for a reliable adhesion bridge, keeping consumption low.
- Dilutable up to 1:10 – with white spirit or ISOPAR® E, adjustable to the desired application method and layer thickness.
- Solids content around 23% – after the solvents evaporate, a thin, rigid silicone resin film remains as the adhesion layer.
- Multiple application methods – suitable for coating, dipping, brushing and spraying, so processing fits the production line.
- Optional heat post-treatment 100–150°C – increases adhesion on difficult substrates such as smooth metals.
Typical Applications
- Pre-treatment of metal parts before applying ELASTOSIL® R silicone rubber.
- Adhesion bridge on ceramic and glass in technical silicone applications.
- Encapsulating and bonding polymer substrates with solid silicone rubber.
- Preparation of smooth or hard-to-bond surfaces via a thin primer layer.
- Production of technical rubber components requiring durable substrate-to-rubber adhesion.
⚠️ Caution: highly flammable. ELASTOSIL® AUX G 3243 has a flash point of 7°C. From this temperature, flammable vapours may form. Keep away from heat, sparks and open flames, do not smoke and take measures against static electricity.
Processing Instructions
- Thoroughly clean all substrates with solvents (e.g. white spirit followed by ethanol or acetone); make sure the surface is dry, clean and grease-free.
- Roughen very smooth surfaces by grinding or blasting; allow metals several hours after cleaning to regenerate their oxide layer.
- Stir the primer thoroughly before use; dilute if necessary up to a maximum of 1:10 with white spirit or ISOPAR® E.
- Apply as thin a layer as possible (1–10 µm, i.e. 5–50 g/m²) by coating, dipping, brushing or spraying.
- Allow the solvent to evaporate for at least 2 hours at room temperature and moderate humidity until a consistent primer film has formed.
- Apply the silicone rubber preferably soon afterwards, but no later than 2 days. Optionally, heat the primed substrate after solvent evaporation to 100–150°C for up to 1 hour for stronger adhesion.
- Always carry out preliminary trials; the final adhesion is determined by substrate, silicone type and processing parameters and reaches its maximum only after a few days.
Storage and Shelf Life
ELASTOSIL® AUX G 3243 is moisture-sensitive. On contact with moisture the primer becomes turbid and its adhesive strength decreases. After use, store the primer in a tightly sealed container, cool (10–25°C) and out of direct sunlight. Stir or shake thoroughly before each use. Shelf life is at least 1 year in the unopened original packaging.
About the Manufacturer
Wacker Chemie AG is a world market leader in the development and production of silicones for industrial and technical applications.
Professional Support
Unsure about the right primer or processing method for your substrate and silicone type? Our team is happy to advise on adhesion, pre-treatment and trial setup. Feel free to contact us for personal advice.
Product Properties
- ColorYellowColor of the finished product
- Viscosity550mPa·sViscosity of the uncured silicone
- Density0.85g/cm³Density of the cured material
Physical Properties
- Flash point7°CMin. temperature at which the product ignites
- Boiling point116°CBoiling point at atmospheric pressure
- Vapour pressure<5.0hPaVapour pressure at 20°C
Application
- Use caseAdhesion-promoting primer for solid silicone rubber on metal, ceramics, glass and polymersIntended use
- Cure conditionRoom temperature or heatCondition under which the material cures
- Active substance23.0%Proportion of active substance
- SolventISOPAR E / xyleen, verdunbaar tot 1:10 met white spirit of ISOPAR ESolvent used
- Application method["Coaten","Dompelen","Borstelen","Spuiten"]How the product is applied
- Reaction timeMinimaal 2 uur afluchten bij kamertemperatuur en matige luchtvochtigheidRequired reaction/flash-off time
Safety Information
GHS classification (danger): this product is highly flammable (liquid and vapour, flash point 7 degrees Celsius), causes skin and serious eye irritation, may irritate the respiratory tract and cause drowsiness or dizziness, may cause damage to organs (hearing organs) through prolonged or repeated exposure and is toxic to aquatic life with long-lasting effects. Keep away from heat, sparks and open flames and do not smoke. Recommended personal protective equipment: wear chemical-resistant safety gloves, close-fitting safety goggles, protective clothing and, where ventilation is insufficient, a respirator with an ABEK filter. Ensure good room and workplace ventilation with extraction at the source, avoid inhaling vapours and mists and wash your hands after use. Always consult the full safety data sheet (SDS) for complete hazard, handling and first-aid information before using this product.| Safety Pictograms | Safety Data Sheets (SDS) |
|---|---|
GHS hazard pictograms
   
Required protection (ISO 7010)
      |
| Signal Word | H‑code | Hazard Statement | P‑codes | P‑statements |
|---|---|---|---|---|
| Danger | H225 | Highly flammable liquid and vapour | P210 P233 P240 P241 P280 P303+P361+P353 P370+P378 |
|
| Warning | H315 | Causes skin irritation | P264 P280 P302+P352 P333+P313 |
|
| Warning | H319 | Causes serious eye irritation | P264 P280 P305+P351+P338 P337+P313 |
|
| Warning | H335 | May cause respiratory irritation | P261 P271 |
|
| Warning | H336 | May cause drowsiness or dizziness | P261 P271 P312 |
|
| Warning | H373 | May cause damage to organs through prolonged or repeated exposure | P260 P501 |
|
| Warning | H411 | Toxic to aquatic life with long lasting effects | P273 P391 P501 |
|
Frequently asked questions
What is the delivery time for my order?
Orders placed and paid on working days are in most cases shipped the same day. Weekend orders are processed on the next working day.
Indicative delivery times: Netherlands usually within 1 working day, Belgium and Germany typically 1–2 working days, other countries depending on destination and carrier. These are guidelines, not guarantees: peak periods, public holidays or carrier delays can have an effect.
What is the return policy?
You have 30 days to return after receipt. Email info@siliconesandmore.com within 30 days of delivery with your name and order number. The full conditions are in our return policy.
How can I track my order?
As soon as your order has shipped, you'll receive a track & trace code by email. It can take up to 24 hours before the code is active.
I have a problem with my order – how do I reach you?
Contact us via our contact page or email info@siliconesandmore.com. We're happy to help you quickly.
Can I order as a business?
Yes. Apply for a business account; we review your application within 3 working days. After that you order while logged in and pay on invoice, with payment terms of 14 days after delivery.
EU businesses outside the Netherlands with a valid VAT number order with VAT reverse-charged (0%, intra-community supply). The VAT number is stored in your business account; it cannot be added to an order after it has been placed.