What is the purpose of the developer in magnetic particle inspection?

The purpose of the developer in magnetic particle inspection is to enhance the contrast of indications. When magnetic particles are applied to a test surface, their visibility can be affected by various factors, including the surface condition and the distribution of the particles. The developer works to draw the magnetic particles out from the surface anomalies, like cracks or discontinuities, allowing them to agglomerate at the flaw site. This results in clearer and more discernible indications that reflect the presence of defects. By increasing contrast, the developer helps inspectors accurately assess the integrity of the material being tested.

The other choices describe functions that do not accurately represent the role of the developer. For example, the developer does not initiate the magnetization process or create a magnetic field; such tasks are accomplished through the use of appropriate equipment and magnetizing techniques. Additionally, while some inspection materials may provide a protective coating, the primary function of the developer is to enhance visibility rather than to protect the surface being inspected.