What is a disadvantage of using the dry method compared to the wet method?

The dry method of magnetic particle testing is less sensitive to smaller surface defects compared to the wet method. This is primarily due to the characteristics of the magnetic particles used. In the dry method, the particles are often larger and tend to have less overall mobility than the finer particles used in the wet method, which can disperse more easily into the surface irregularities of the test object. As a result, the dry method can miss finer defects that the wet method would typically capture due to its more uniform distribution and the ability to adhere to various surface conditions.

This is particularly important in applications where detecting small cracks or discontinuities is critical for the integrity and safety of the component being tested. The limitations in detecting finer defects make the dry method less effective in certain critical inspections compared to its wet counterpart.