Which of the following is NOT necessarily contained in all wet aqueous developers?

• A. Corrosion inhibitors.
• B. Dye indicator.
• C. Biocides.
• D. Wetting agents.

Answer: (B)

In wet aqueous developers, the formulation is meant to help reveal defects while protecting the part and keeping the system stable. You’ll typically find wetting agents included to lower surface tension and improve how the penetrant flows into tiny flaws. Biocides are added to prevent microbial growth in the water-based medium, and corrosion inhibitors help protect the metal surface during development. A dye indicator, however, is not required in every formulation. Some developers are colorless or rely on the penetrant’s own color or fluorescence for indication, so the dye indicator is not necessarily contained in all wet aqueous developers.