with the hot surface iron on the steel and forms a compound normally referred to as SCALE. Chemically speaking, this scale can be made up of one or any or all of these separate compounds: Ferrous Oxide - scale (black, scaly) Ferric Oxide - rust (brown, powdery) Ferrous-Ferric Oxide - magnetite (blue black, magnetic) This scale, no matter what proportion of the three above compounds it contains, is generally a very hard, brittle coating, from between paper thick to 1/32” thick, adhering to the surface of the steel. No ‘foreign’ material can be present when the steel is further processed such as in sizing by cold rolling or drawing or forming by stamping etc. This means that the scale must be removed prior to this processing.