Magnetic Particle Testing is a relatively inexpensive yet portable and reliable means of NDE for the detection of flaws in ferrous materials. There are several methods to magnetic particle testing such as the yoke technique and the use of a magnetic coil. Both of these can be used with white light visible or fluorescent when used with a black light. Even though there are different ways to perform MT they are all used to do the same thing. This is to apply a magnetic field to the area you are inspecting and then adding a form of magnetic particle, the indications will cause a break in the field creating a north and South Pole. This will then cause the magnetic particles to attract to the indication showing you any discontinuities in the weld.