Which of the following is NOT a factor affecting the visible indications during Magnetic Particle Testing?

In Magnetic Particle Testing, visible indications are critical for assessing the presence of surface and near-surface defects in ferromagnetic materials. Several factors play significant roles in influencing the clarity and visibility of these indications.

The type of solvent used is not a factor that directly affects the visible indications during the testing process. While solvents are important in preparing the surface by removing oils, dirt, and other contaminants to ensure proper adhesion of the magnetic particles, they do not influence the behavior or characteristics of the magnetic particles themselves or the resultant indications. The effectiveness of the solvent is more related to cleanliness rather than the visibility of indications.

On the other hand, particle size, surface texture, and ambient lighting conditions directly impact how well defects can be seen. For instance, particle size determines how well the particles gather at defect sites; finer particles can highlight smaller defects more effectively. Surface texture affects how magnetic particles adhere and whether they can adequately form indications. Ambient lighting conditions are crucial as they affect how reflections and shadows may either enhance or obscure the visibility of indications on the tested surface.

Thus, the correct answer identifies the type of solvent used as the factor that does not influence the visible indications in the context of Magnetic Particle Testing.