ABSTRACT
Metals are the group of materials that are at most risk in our atmosphere. In their natural state they exist as oxides and sulphides before extraction into pure elements. Coatings applied to metals must do the following: protect the metal substrate from initiators of corrosion such as air or water, and actively inhibit corrosion; and provide effective bonding to the metal. The most important part of coating a metal is the initial cleaning and preparation. As the metals most commonly coated are irons and steels, the purpose of cleaning is generally to remove an oxide film. Coating systems can be organic or inorganic, but are preceded by phosphate treatments which act as corrosion inhibitors. Wherever possible these finishes should be carried out in controlled conditions, particularly to enable blast-cleaning to be properly carried out. Weathering steels are alloyed steels which contain a range of elements that will provide a coating to steel so that it will corrode no further.
