What is the primary purpose of pre-cleaning parts before penetrant application?

The primary purpose of pre-cleaning parts before penetrant application is to remove contaminants that could mask defects. This step is crucial because any contaminants—such as dirt, oils, grease, paint, or rust—on the surface of the material can obstruct the penetrant from entering any flaws or discontinuities present. If the surface is not adequately cleaned, these contaminants may hide defects, leading to incorrect inspection results and potentially allowing serious issues to go undetected. Therefore, thorough cleaning is essential to ensure the effectiveness of the penetrant testing process and to obtain accurate and reliable results.