Magnetic particle testing is a nondestructive test which will find surface and slight subsurface indications in ferromagnetic materials. Although widely used in lab and large production facilities International Inspection specializes in field inspections. While for most inspections a yoke is used there are also prods and coils that are used for certain applications.
The dry powder method is the most employed for field inspection. It is a rapid, effective inspection technique and does not require any special lighting for evaluation.
Wet visible and wet fluorescent methods use magnetic particles suspended in liquid. The visible method requires white light while the fluorescent method uses ultraviolet light for evaluation.