Peel test

An adhesive bond test in which two overlapping substrates bonded over a defined area are pulled in tension, loading the joint in shear until failure. It is the most common way to compare structural adhesive performance on representative substrates, with methods including EN 1465, ISO 4587 and ASTM D1002.

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.

Failure of a bonded joint within the body of the adhesive itself, leaving adhesive on both substrates, as opposed to adhesive failure at the interface. In joint testing it is generally the preferred failure mode, because it shows the bond to each substrate was stronger than the adhesive, so the adhesive's full capability was realised.