with parts of unusual shape. Direct current can be used to demagnetize if there is provision for current decay or
reduction and means of reversing the direction of the current. Demagnetization accomplished with direct current is the
most complete and effective possible.
limits of Demagnetization. The limits of demagnetization may be considered to be either the maximum extent to
which the part can be demagnetized by available procedures, or the level to which the earth's field will permit it to
become demagnetized. These limits may be further modified by the practical degree or limit of demagnetization which is
actually desired or necessary. A common accepted practice is to consider a part demagnetized when the magnetic field
strength of the residual field is at its lowest level possible. However, specification for demagnetization should be
examined to consider the preceeding facts. It is unquestionably true that specification for demagnetization called for
levels of residual fields lower than are practicable or even possible to attain. If demagnetization of parts is called for, the
specification should state a limit of permissible residual field that it is reasonably possible to achieve. Unrealistic
requirements should be modified in light of what needs to be or what can be done.