What is the main purpose of using a black light during fluorescent penetrant inspection?

The primary purpose of using a black light during fluorescent penetrant inspection is to make the indications visible. This method relies on fluorescent penetrants that glow under ultraviolet (UV) light, specifically emitted by a black light. When the penetrant fills surface-breaking defects like cracks or voids in a material, the black light illuminates these areas, making the otherwise invisible indications stand out with a bright fluorescence. This visibility is crucial for inspectors to accurately assess and evaluate the integrity of the material being inspected, allowing for the identification of flaws that could compromise safety and performance.

The use of black light does not inherently enhance general lighting conditions, measure crack depths, or clean parts effectively, as those functions are outside the intended application of fluorescent penetrant inspection.