What do the terms "dry," "aqueous wet," and "nonaqueous wet" refer to?

The terms "dry," "aqueous wet," and "nonaqueous wet" specifically refer to methods of applying developers in non-destructive testing, particularly in the context of penetrant testing. These types of developers are utilized after the penetrant has been applied and allowed to dwell on the test surface to highlight possible defects.

Dry developers absorb the excess penetrant and provide a contrasting color to make indications more visible. Aqueous wet developers utilize water-based solutions, which are often easier to clean and apply. Nonaqueous wet developers, on the other hand, use solvent-based solutions that don't rely on water, which may be preferable in certain environments or for certain types of metals where water could cause corrosion.

Understanding these types of developers is crucial for anyone involved in non-destructive testing, as the choice of developer can significantly impact the effectiveness of the inspection. The other options, while related to non-destructive testing, do not specifically apply to the terms mentioned in the question, as penetrants and test specimens are separate aspects of the testing process.