The control with magnetic particles, also known as magnetoscopy, allows to locate any surface or sub-surface defects.
This technique is applicable exclusively to ferromagnetic materials and involves the magnetization of the component to be controlled and the application of a detector containing ferromagnetic particles. The presence of any discontinuity causes the flow lines of the magnetic field that attract these particles.
The final inspection can take place under natural light, when using a color contrast detector or, in dark environments, by a Wood's lamp, using a fluorescent detector.