What can hinder the visibility of magnetic particles during a test?

The visibility of magnetic particles during a magnetic particle testing (MPT) procedure is critical for accurately detecting surface and near-surface defects. The contrast between the color of the magnetic particles and their background plays a significant role in this visibility. If there is insufficient contrast, it becomes difficult to discern the particles against the surface being tested, potentially leading to missed indications of defects. For example, if both the magnetic particles and the background surface are similar in color, it can be challenging to identify the pattern of indications that may suggest a flaw.

Proper contrast enhances visibility, allowing for clearer identification of any defects that the particles gather around due to the magnetic field. Thus, ensuring there is adequate contrast is essential for effective magnetic particle testing.