What types of adhesion checks?
A St Andrews Cross Cut test is recommended. This is two lines cut through the coating (with a sharp decorators knife i.e. ‘Stanley’ type of similar) to the substrate beneath, at the ‘V’ intersection of the lines the knife should test the adhesion by inserting the point of the knife at the ‘V’ intersection and firmly dragging or flicking the knife upwards or forwards. This is a practical on site adhesion check that will give an indication of the factory coating adhesion, and whether it will support a redecoration. The coating shall be deemed sound to overpaint if no or very little of the coating is removed by the above test. If the coating can be quite readily chased up the surface with the knife, it shall be deemed unsound, and removal of the coating is required prior to treatment.
