Why should aluminum alloy test specimens be thoroughly cleaned after liquid penetrant testing?

After liquid penetrant testing, aluminum alloy test specimens must be thoroughly cleaned primarily to prevent any potential damage to the surface integrity of the material. The alkaline content present in some wet developers can lead to surface pitting on aluminum alloys if not removed properly. Aluminum is particularly susceptible to alkaline corrosion, which can undermine the material's mechanical properties and overall performance.

Cleaning the specimen ensures that any residues from the testing process, such as the alkaline substances, are completely removed, maintaining the integrity of the aluminum surface. This cleaning step is critical in ensuring that the alloy does not suffer any undesirable effects, which could potentially lead to failure in actual applications.