SILTRUST™ SS4120 PRIMER (Clear)
GEE10287
SILTRUST™ SS4120 – Clear, Low-Solids Primer for Addition-Cure Silicones
SILTRUST™ SS4120 is a one component, ready to use, (Clear), colourless primer specifically formulated to promote adhesion between addition-cure RTV silicone rubber compounds and a wide range of difficult to bond substrates. Unlike pigmented primers, SS4120 is optically clear, making it ideal for applications where visual clarity or aesthetic neutrality is required, such as in transparent or light-colored assemblies.
SS4120 is a low-solids (3%) solvent-based solution using ethanol and methanol as carriers, allowing for easy application and quick drying at room temperature. It is especially recommended for use with Momentive’s addition-cure RTV systems (e.g., RTV615, RTV655, RTV61X6 Series), where strong, durable silicone to substrate bonds are critical.
Key Features
- Clear and colourless – preserves the appearance of light or transparent components.
- Optimised for addition-cure RTVs – enhances adhesion without interfering with platinum-cure chemistry
- Low-solids formulation (3%) – minimises residue while ensuring effective bonding.
- Fast room-temperature dry time – typically ready for RTV application in 30 minutes
- Easy application by brush, wipe, or dip.
- Compatible with sensitive substrates where discolouration or staining must be avoided
Typical Applications
- Bonding addition-cure silicones to metals, glass, or engineered plastics in optical or aesthetic assemblies
- Medical, automotive, or electronics applications requiring invisible primer films
- Potting or encapsulation processes where substrate visibility is important
- Use in cleanroom or precision manufacturing environments
- Substrate Compatibility
While Momentive RTV silicones often bond well without primers, SS4120 is recommended when maximum adhesion is needed on:
- Metals (aluminium, stainless steel, etc.)
- Glass and ceramics
- Certain engineered thermoplastics (when compatible with alcohol-based solvents
Technical Notes
- Solvent system: Ethanol / Methanol
- Flash point: –0.5°C (31°F) – flammable
- Dry time: 30 minutes at 25°C (77°F) and ≥25% RH
- Film thickness: 0.01–0.02 mm (0.5 mil) recommended
- Storage: Keep container tightly closed; decant clear liquid if precipitate forms
- Compatible with brush, wipe, or dip application methods
- Not recommended for spray application due to volatility and low solids content.
Certifications & Compliance
- FDA compliant – suitable for use in food contact applications per FDA regulations
Packaging Options
- Available in a standard solvent-resistant bottle for industrial use.
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SILTRUST™ SS4120 – Clear, Low-Solids Primer for Addition-Cure Silicones
SILTRUST™ SS4120 is a one component, ready to use, (Clear), colourless primer specifically formulated to promote adhesion between addition-cure RTV silicone rubber compounds and a wide range of difficult to bond substrates. Unlike pigmented primers, SS4120 is optically clear, making it ideal for applications where visual clarity or aesthetic neutrality is required, such as in transparent or light-colored assemblies.
SS4120 is a low-solids (3%) solvent-based solution using ethanol and methanol as carriers, allowing for easy application and quick drying at room temperature. It is especially recommended for use with Momentive’s addition-cure RTV systems (e.g., RTV615, RTV655, RTV61X6 Series), where strong, durable silicone to substrate bonds are critical.