Which statement describes a disadvantage of using dry developer in penetrant inspection?

• A. Does not form contrast background so cannot be used with visible systems
• B. Easy to coat the entire part
• C. Easily cleaned from the surface after inspection
• D. Portable spray can for application

Answer: (A)

Dry developer is a powdery coating used after the penetrant is removed to draw it out of defects. It doesn’t wet the surface to create a uniform background, so for visible dye penetrant systems it often fails to produce the clear, contrasting field needed to make indications stand out. In visible systems, you rely on a bright, consistent background so the colored penetrant indications show up clearly; a powdery background from dry developer can be uneven or insufficient, masking or reducing visibility of flaws. Fluorescent penetrant systems, on the other hand, rely on the fluorescence of the penetrant rather than background contrast, so dry developer can be used there. The other statements describe ease of coating, cleaning, or portability, which are not disadvantages and thus don’t describe the limitation of dry developer for visible systems.