Cross-hatch adhesion test

A test in which a metal dolly is glued to a coating or applied layer and pulled off perpendicular to the surface with a calibrated instrument, recording the tensile stress at detachment and the failure mode. Standardised in ISO 4624 and ASTM D4541, it is widely used on site to verify the adhesion of coatings, screeds and liquid-applied membranes.

The thickness of a coating measured after it has dried or cured, usually specified per coat and for the complete system. It is a key quality control parameter, checked non-destructively on metal substrates with magnetic induction or eddy current gauges.

A preparatory coating applied to a substrate before an adhesive, sealant, coating or waterproofing membrane, improving adhesion by sealing porosity, binding dust or providing a chemically compatible surface. Primer selection depends on both the substrate and the product to be applied over it.