Disclosed is a method for the non-destructive testing of workpiece surfaces of a workpiece by means of fluorescent penetrant testing or dye penetrant testing. The method comprises applying a penetrant to the region of the workpiece surface to be examined, thereby allowing the penetrant to penetrate into possible recesses in the workpiece surface, applying a developer to the region of the workpiece surface to be tested; bleaching the penetrant by a gaseous or liquid oxidant; and visually assessing the penetrant that has remained in the recesses present in the workpiece surface.