upper surface 20 of the ring 16 a force applying member e g a plunger 22 which is moveable in the direction of the arrows 24 in fig1 in a support sleeve 26 contacts the surface of the coated workpiece 18 a mechanism not shown is provided to bias the plunger 22 against the surface of the coating on the workpiece 18 and to increase the force in a controlled and uniform manner scales 28 and 30 which are indicative of the force and the deflection at any given instant of time are provided on the apparatus optionally and if the apparatus is to be used in a factory environment by a human tester the apparatus also includes pass and fail indicator lights 32 and 34 a setting knob 36 is provided to calibrate the apparatus to a selected pass fail limit also optionally a chart recorder 38 may be associated with the apparatus 10 to make a chart record of the force deflection curve as illustrated in the enlarged partial section of fig2 the workpiece 18 which is the subject of the present testing method comprises a substrate 40 which carries a coating 42 adhered thereto one example of a typical workpiece 18 is that mentioned above.