How do you see from the surface that you are galvanized or nickel plated?
The process of baking and heating the equivalent magnetic materials at elevated temperatures, so high temperature will make the interaction domain between the direction of magnetization of magnetic domains weakened, can rotate freely, then the orientation of the situation has changed, become disorderly, also is the macro is not magnetic, the demagnetization.
The internal magnetic material from many domains can be considered to be composed of magnetic domain magnetic material pieces, usually called "magnetic remanent magnetization, magnetic domain magnetic materials is the internal orientation appeared in the absence of external magnetic field under the condition of macro generated magnetic.
Then, in order to restore the condition, it is necessary to re apply the magnetic field, allowing the external magnetic field to induce the magnetic domain inside the magnetic material to re arrange, that is, to re magnetization.
