Wood, paper, fabric, porous ceramics and roughened metal give adhesives holes and undercuts to fill. Once cured, the adhesive keys into the surface like roots in soil. Mechanical interlock adds to chemical bonding and is one reason abrading or grit-blasting improves strength, along with stripping off weak surface layers. On smooth plastics and glass, chemistry has to do almost all the work.
Grit blast gives you mechanical interlock on the steel, the polished stuff was popping clean off.
Also heard as
- mechanical adhesion
- mechanical keying
Related terms
Scuff
To roughen a bonding surface lightly with an abrasive pad or paper to remove gloss and contamination.
Wetting
How well a liquid adhesive spreads over and makes intimate contact with a surface.
Peel ply
A fabric layer cured onto a composite surface and torn off just before bonding to expose a clean, textured face.
Adherend
Each of the parts in a bonded joint; the surface the adhesive has to grip.