Penetrant testing using dual-response penetrant media
Capillary testing with combined dye and fluorescent penetrants is a non-destructive method for detecting open surface defects. Colored or fluorescent liquids are applied, which accumulate in cracks and reveal the exact crack path.
Physico-chemical mechanism of action
Colored or fluorescent liquids are applied to the surface to be inspected. Due to capillary forces between the fluid molecules and the material, the inspection medium penetrates into cracks and forms a visible line there.
Metallurgical relevance & risks during welding
This method detects micro- and macro-cracks as well as other surface defects that are not visible with other methods. Incorrect application or failure to clean the surface can lead to inaccurate results.
Workshop practice & instructions
1. Prepare the surface to be inspected thoroughly, removing all dirt and oil layers.
2. Apply the inspection medium to the surface and allow it a little time to penetrate into cracks.
3. Remove excess inspection medium with a clean cloth or a brush.
4. Observe the surface pattern under normal or fluorescent lighting to detect the cracks.