Primer for Silicone Rubber Most silicones often don't chemically bond to a surface. Therefore, a primer must be used to promote adhesion. Our silicone primers activate the surface via OH bridges and silane/siloxane chemistry, allowing silicone rubber (RTV-2/LSR) to bond reliably to glass, metal, aluminum, ceramics, select plastics, and even...
✔ Provides excellent adhesion onto various substrates.
✔ For addition curing silicone
✔ Solvent based
✔ Various application methods (e.g. coating, dipping, brushing, spraying)
✔ Further dilution in organic solvents possible
✔ Increases the adhesion between condensation and addition curing silicone and various surfaces
✔ Used for Arresters, Cable Accessories, Insulators
✔Organic solvent, free of toluene and aromatic solvents
✔ Increases the adhesion between condensation and addition curing silicone and various surfaces
✔ Functions on metals, wood, various plastics such as PETG
✔ Soluble in white spirit or alcohol
✔ Works with silicones with a high oil content
Primer for Silicone Rubber
Most silicones often don't chemically bond to a surface. Therefore, a primer must be used to promote adhesion. Our silicone primers activate the surface via OH bridges and silane/siloxane chemistry, allowing silicone rubber (RTV-2/LSR) to bond reliably to glass, metal, aluminum, ceramics, select plastics, and even wood. Choose toluene-free primers where necessary and adjust the layer thickness to the substrate for maximum adhesion.
Coating thickness rule: On non-absorbent surfaces (glass/metal/aluminum), the primer should be applied ultra-thinly—practically monomolecularly. On absorbent surfaces (porous wood), more can be applied, or choose a thicker primer.
When do you use a primer for silicone rubber?
→ Bonding of RTV-2/LSR silicone to glass, steel, aluminum, ceramic or coated substrates
→ On wood or other absorbent surfaces for better keying and longer open time
→ As an adhesion promoter before over-spraying/coating or insert-molding of silicone parts
Layer thickness & substrate
Non-absorbent (glass, metal, aluminium)
Degrease, dry and dust-free
Apply ultra-thin (cloth/tampon/HVLP): film should be barely visible
Flash according to TDS; apply silicone within the processing window
Apply silicone inside window: if exceeded, prime again
Adhesion test: small peel/shear test before series production
Frequently asked questions about silicone primer
Does this work on both addition (platinum) and condensation silicones?
Yes, but check the product sheet. Most of the above are designed as adhesion promoters for RTV-2/LSR and perform best with additive systems.
How thin is "thin enough" on glass/metal?
A nearly invisible film: practically monomolecular. Excessively thick layers reduce adhesion and can become brittle.
When do I choose a 2-component silicone primer?
For critical substrates or absorbent surfaces (e.g. wood) or when you require a longer open time and higher final adhesion (G791 A/B, AV).
Is G790 really toluene-free?
Yes, G790 is specifically formulated as a toluene-free primer. Always check the current TDS/SDS for the solvent profile.
Advice & order
Are you unsure about whether to choose G790 (toluene-free), G795, G791 A/B, ELASTOSIL® AUX G 3243, or Primer AV? We'll quickly help you with substrate selection, layer thickness, and application.
Here is an overview of primers and when to use them:
Primers for silicones overview.pdf