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 Chornique: The Journal of Chivalry #13.