Untreated magnesium has a lower corrosion rate in an industrial atmosphere than mild steel
The practical aspect of the protection of magnesium alloys, in severe conditions especially, is very closely bound up on one hand with design and on the other with assembly. Schemes that are otherwise good may miscarry for lack of thought at the design stage or because of faulty or careless assembly. In general, the corrosive substances to be avoided are aqueous solutions of salts and acids. They may be derived from salt spray or from industrial gases such as sulphur dioxide. Most of the impurities in the atmosphere which lead to the corrosion and rotting of structural iron and steel will also attack magnesium, though sulphur gases are less damaging than chlorides. In a similar way corrosive conditions to be avoided are the wetting, and especially the persistent wetting, of the metal surface by such solutions as those described above. They may take the form of rain, seawater splashes, condensate from the cooling of highly humid atmospheres and the like. If these can be kept in check, little trouble will result.