The failure to completely remove acid materials from a part before fluorescent penetrant is applied will result in

The failure to completely remove acid materials from a part before fluorescent penetrant is applied will result in

• A. An increase in the fluorescence of the penetrant
• B. No effect on fluorescence
• C. A decrease in the fluorescence of the penetrant
• D. Color change to green

Answer: (C)

The test is about how surface cleanliness affects the penetrant’s ability to wet and enter flaws. If acid residues remain on the part, they form a film that hinders proper wetting and can interfere with how the penetrant penetrates into cracks and pores. With less penetrant entering defects, there will be fewer sites to fluoresce under UV light, so the observed fluorescence is weaker. That’s why the correct result is a decrease in fluorescence. The other ideas don’t fit: residues don’t cause more fluorescence, a lack of effect isn’t accurate because cleanliness matters, and the visible color change (to green) isn’t how fluorescence is evaluated in this inspection.

The test is about how surface cleanliness affects the penetrant’s ability to wet and enter flaws. If acid residues remain on the part, they form a film that hinders proper wetting and can interfere with how the penetrant penetrates into cracks and pores. With less penetrant entering defects, there will be fewer sites to fluoresce under UV light, so the observed fluorescence is weaker. That’s why the correct result is a decrease in fluorescence. The other ideas don’t fit: residues don’t cause more fluorescence, a lack of effect isn’t accurate because cleanliness matters, and the visible color change (to green) isn’t how fluorescence is evaluated in this inspection.