A test, ASTM D4541 or ISO 4624, in which a metal dolly is glued to the coating, the film around it is scored through, and a portable tester pulls the dolly straight off while recording the force in psi or MPa. The value and the failure mode, whether at the steel, between coats, within a coat or in the glue, show where the system is weakest. Specs for protective coatings often require several hundred psi or more.
Pull-off adhesion test let go at 400 psi, all adhesive at the primer, so the surface prep wasn't right.
Also heard as
- pull-off test
- dolly test
- adhesion test
Related terms
Chalking
Powdery residue on an aging coating surface as sunlight breaks down the binder.
Anchor profile
Peak-to-valley roughness that blasting cuts into steel so a coating can grip, given in mils or microns.
Cathodic disbondment
Loss of coating adhesion around a holiday caused by the alkali and hydrogen that cathodic protection generates.
DFT
Dry film thickness: the thickness of a cured coating layer, measured in mils or microns.