Dye penetrants, fluorescent penetrants, wet and dry developer, cleaning agents
Crack detection by means of capillary attraction
Penetrants testing is based on the capillary action at defects which are open to the surface, as e.g. with cracks, and is a comparably easy examination method: After spraying the testing agent penetrates into the crack due to the capillary action. Then, after the successive intermediate cleaning the developer becomes sprayed on. After drying the developer draws the penetrant from the crack and the indication widens. The trace of the crack becomes visible within a few minutes.