Why is cleaning of the part prior to penetrant inspection essential?

The cleaning of a part prior to penetrant inspection is essential primarily because it ensures that surface contaminants do not interfere with the access of the penetrant to potential defects. Contaminants such as dirt, grease, oil, or paint can create a barrier that prevents the penetrant from entering cracks or other discontinuities in the material. If these contaminants are not removed, they can mask defects, leading to false negatives during inspection. This can compromise the integrity of the part and ultimately lead to safety issues if undetected flaws exist. Thus, thorough cleaning is critical to achieving reliable and accurate results during the liquid penetrant testing process.