Liquid Penetrant Inspection (LPI) Level 1 Practice Test

With solvent-removable penetrants, the most important precaution is controlling the amount of solvent applied to remove the excess penetrant while leaving a thin, uniform film in any defects. If too much solvent is used, penetrant can be washed out of defects, reducing sensitivity and the contrast of indications. This can lead to missed flaws or smeared, unclear indications. Keeping the solvent amount limited ensures the penetrant stays in cracks and pores long enough for the developer to draw it out and reveal clear indications, while avoiding excessive removal or background staining.

Choosing to use only water for rinsing applies to water-washable penetrants, not solvent-removable types. Applying a lot of solvent would be counterproductive, potentially washing away the penetrant. Using no penetrant at all defeats the purpose of the inspection.