Why is cleaning the part prior to penetrant inspection essential?

Cleaning the part prior to penetrant inspection is vital because surface contaminants can obstruct the penetrant from accessing any discontinuities present in the material. The purpose of penetrant inspection is to detect surface defects, such as cracks or voids, that are not visible to the naked eye. If dirt, grease, paint, or other contaminants are present on the surface, they can form a barrier, preventing the penetrant from entering these defects.

Therefore, effective cleaning ensures that the inspection can accurately reveal any flaws, allowing for a reliable assessment of the part's integrity. This step is fundamental in achieving the desired sensitivity and accuracy of the penetrant inspection process.