The processes through which armour is
hardened through heating. In general, most
iron or
ferrous armour is hardened either through work hardening (done by
hammering ) or by heating it to its critical temperature (dependent upon the technique used) and then quenched in water, urine, oil or other more secret substances. Prior to the 14th century, most hardened pieces were worked,
planished , from the
hammer rather than heat treated. During the 15th century, there is some evidence that the German armourers, particularly in Augsburg, began to use a sophisticated two step method that achieved a superior
hardness and a resiliance to
brittleness . See especially Theodore Monnich's article in
Chronique: The Journal of Chivalry #13 .