What is a common issue caused by contaminants on the surface prior to Liquid Penetrant Testing?

Contaminants on the surface prior to conducting Liquid Penetrant Testing can significantly impact the results of the inspection. When surfaces are contaminated with oils, greases, dirt, or other materials, these substances can create a barrier that inhibits the penetrant from properly entering and filling the surface defects. This situation leads to reduced sensitivity in detecting flaws, as tiny discontinuities may be obscured or entirely missed during the test.

Additionally, contaminants can cause false indications or misleading results by trapping the penetrant or causing it to bleed out unevenly, mimicking actual defects. Therefore, the presence of contaminants can compromise the integrity of the testing process, resulting in either missed defects or erroneous readings, thus highlighting the critical importance of surface preparation before testing.