Abstract: A magnetic field indicator is provided which visually indicates the presence of a potentially harmful magnetic field by means of a magnetically responsive additive. In one embodiment, the additive comprises ferrite-encapsulating microspheres which contain ferrite flakes. The ferrite flakes are movably suspended within the microspheres so that the flakes are free to align with the lines of flux of a magnetic field. In the presence of a magnetic field, the ferrite flakes align themselves with the lines of flux of the magnetic field, thereby changing the reflectivity and other visual characteristics of the material which incorporates the ferrite flakes, so that an observer is able to visually detect the presence of a magnetic field. The magnetic field indicator may be embodied in accordance with a variety of applications.