Inspection Trends

Q: I’m hoping you can give me a pointer or two on how to take a photograph of a dry powder magnetic particle indication for inclusion in a report.

A: Taking a photograph of a dry powder magnetic particle indication that shows sufficient detail is often a question of contrast. The dry magnetic particles come in a couple of different colors, so they naturally provide enough contrast against the background of the test piece. The idea is to enhance the contrast to make the indication more easily seen with the unaided eye. However, the indication can still be difficult to see in the photograph. You need a way to enhance the contrast between the magnetic particle indication and the surface of the test piece.

I typically perform a dry magnetic particle testing using an alternating current (AC) magnetic yoke. I reorient the legs of the yoke to produce the strongest indication. The indication is easily seen, but it may not produce the best image once photographed. I then spray a light coating of the nonaqueous developer on the surface of the test piece. The developer should not be applied too thick but just enough to obscure the surface of the test piece. Once the nonaqueous developer is completely dry, the magnetic particle test is performed with the legs of the yoke positioned to produce a clear indication.

I also find black dry magnetic particles on the white developer provide great contrast. Red magnetic particles work, but the contrast is slightly reduced.

You can also buy white lacquer paint from the supplier you purchase your magnetic particle test materials from, but it is another consumable you have to carry with you. My experience is the nonaqueous developer dries faster than the lacquer and is easier to remove once the test is complete.

The Society is not responsible for any statements made or opinions expressed herein. Data and information developed by the authors are for specific informational purposes only and are not intended for use without independent, substantiating investigation on the part of potential users.

ALBERT J. MOORE JR. (amoore999@comcast.net) is president and owner of NAVSEA Solutions/Marion Testing & Inspection, Burlington, Conn. He is an AWS Senior Certified Welding Inspector and an ASNT NDT Level III. He is also a member of the AWS Qualification & Certification Committee on Methods of Inspection.