When metal is subjected to a very high temperature bath, that process is called annealing. The temperature is slowly increased to a max temperature where it is stabilized for a period of time, and then the temperature is slowly reduced back to room temperature. This process will leave the metal in its softest state. For a reed switch this is very important because this point is also where the nickel/iron leads have near zero magnetic retentivity. This means when the reed switch contacts are subjected to a magnetic field and then the magnetic field is removed, there will be no residual magnetism on the leads.
