Which of the following is NOT listed as a function of penetrant developers?

• A. Reduces the surface roughness of the part.
• B. Increases the effective size of the penetrant indication.
• C. Aids in the extraction of entrapped penetrant.
• D. Increases the contrast between the indication and the background.

Answer: (A)

In liquid penetrant inspection, the developer’s job is to draw penetrant out of defects and provide a contrasting, visible bloom that makes the flaw easy to see. The developer helps by increasing the apparent size of the indication, since penetrant wicks into and then spreads from the defect as the developer dries, making the flaw appear larger at the surface. It also aids in extracting penetrant by pulling it toward the surface so the indication forms clearly, and it enhances contrast between the indication and the background, giving a bright, easily detectable signal under the inspection light. It does not change the part’s surface roughness—texture is a property of the part, not something the developer alters. So reducing surface roughness is not a function of penetrant developers.