mpiThe Magnetic Testing method can be used on ferromagnetic materials to reveal surface discontinuities and, to a limited degree, those located below the surface. It is an extremely cost effective method used primarily for the detection of cracks. Following magnetisation the specimen is covered with very fine iron particles either dry or suspended in a liquid. Surface breaking flaws distort the magnetic field causing local magnetic flux leakage that attracts the iron particles producing a build-up that can be seen visually.