The principle of the method specified is bonding the finished side of part of a strip of leather to an adherend-plate by means of heat-reactivated adhesive film, applying force to the free end of the strip to peel the leather from the finish over a given distance, the finish layer remaining on the adherend-plate together with the film of adhesive. The force required is measured and reported as the adhesion of the finish to the leather. The method is valid for all finished leathers with a smooth surface which can be bonded to an adherend-plate without the adhesive penetrating into the finish.