3M Primer 94 is an adhesion promoter for use with VHB (Very High Bond) tapes on critical or low-energy surfaces. It cleans, activates and optimises the substrate before tape application, giving a stronger bond on metal, glass, plastic, wood, concrete and painted surfaces. Supplied in a 236ml tin.

Key features

• Purpose, adhesion promoter for use with 3M VHB and other high-strength bonding tapes
• Surface compatibility, metal, glass, PE, PP, ABS, PET/PBT blends, concrete, wood and painted metal
• Surface prep, removes contaminants and activates surface energy for improved tape contact
• Bond performance, enhances chemical interaction between tape and substrate
• Use case, supports full bond strength on low-energy or challenging surfaces where tape alone may not adhere well
• Size, 236ml tin

Product overview

Surface preparation matters when bonding with VHB tape. Even a clean-looking metal or painted surface can carry residual oils, moisture or oxidation that weaken adhesion over time. Primer 94 activates the surface and removes contaminants first, so the tape achieves its full long-term hold.

Before applying the primer, clean contaminated surfaces with a 50/50 mixture of isopropyl alcohol and water using a clean, lint-free cloth. Let the surface dry fully, apply the primer, then let that dry before fitting the tape.

Applications

Used ahead of VHB tape in flat roof solar panel mounting, on rail and tape installations across metal and sandwich panel roofs, and for VHB bonding on painted metal, glass and plastic in signage, construction and automotive assembly.

Installation and safety notes

Apply in a well-ventilated area, away from heat sources and open flame. Let the primer dry fully before taping. Follow the 3M product data sheet for full application and safety guidance. For flat roof solar mounting, check that the tape and primer are rated for the expected load, wind uplift and temperature range of the installation.