What action should be taken if contamination is suspected during penetrant testing?

When contamination is suspected during penetrant testing, the most appropriate action is to clean the surface thoroughly and reapply the penetrant. This is crucial because contaminants can affect the ability of the penetrant to properly adhere to the surface and fill surface discontinuities, which may lead to false readings or missed defects. Cleaning ensures that the surface is free of any substances that could interfere with the testing process, thereby improving the reliability and accuracy of the results.

Reapplying the penetrant after cleaning helps to ensure that any indications observed during the testing are legitimate and not artifacts caused by the contaminants. This step is fundamental in achieving a valid test outcome, as it upholds the integrity of the testing procedure and allows for proper evaluation of the material being tested.