What do filters for ultraviolet lights effectively remove?

Filters for ultraviolet lights are specifically designed to effectively remove visible light from the light source that emits ultraviolet radiation. This is crucial in liquid penetrant testing because the presence of visible light can interfere with the visibility of the fluorescent penetrants used in the testing process. By filtering out visible light, the inspector can clearly see the fluorescent indications against a dark background, thus enhancing detection and interpretation of any surface flaws within the tested material.

In the context of effective operation, ultraviolet light is primarily used during the examination phase where the fluorescent penetrant, excited by UV light, emits visible fluorescence. However, to optimize this process, it's essential to eliminate other light spectrums that may diminish the contrast needed to spot defects.