Rust in History To the great majority of people, corrosion means rust, an almost universal object of hatred. `Rust' is, of course, the name which has more recently been specifically reserved for the corrosion of iron, while `corrosion' is the destructive phenomenon which affects almost all metals. Although iron was not the first metal used by man, it has certainly been the most used, and must have been one of the first with which serious corrosion problems were obtained. It is not, therefore, surprising that the terms corrosion and rust are almost synonymous. (reference) The great Roman philosopher, Pliny, AD 23-79, wrote at length about ferrum corrumpitur, or spoiled iron, for by his time the Roman Empire had been established as the world's foremost civilization, a distinction due partly to the extensive use of iron for weaponry and other artifacts. To the fighters of old, rust was something of a mixed blessing. In the eleventh century, a Norman knight, William de Lacey, lost his way during a hunting expedition into the thickly wooded and swampy Vale of Ewas, in Wales. He came across the remains of St David's hermitage whereupon, overcome by an urge to mend his sinful ways, he decided to dedicate the remainder of his days to religious contemplation and rebuilding the chapel. Legend has it that he never for the rest of his life removed his armor. (image courtesy) One explanation for this strange behavior was that it was a self-imposed penance. More likely, however, is that he was prevented from doing so because of corrosion brought about by the dank atmosphere of the valley. Corrosion of arms and armor has also been advantageous. The techniques of bluing and gilding were frequently used to protect steel objects, for, it was found that the application of a variety of heat treatments created highly protective films of oxide . These, with skill, could turn functional weaponry into beautiful works of art. The Romans must have been vexed by the susceptibility of iron to rust, for, in true scientific fashion, Pliny asked himself the question: why should iron corrode more easily than other metals? Lacking the ability to investigate the problem experimentally, he arrived at the metaphysical solution that it is because iron is both the best and the worst of man's servants. Although very useful domestically, it is also the metal of war, slaughter and brigandage. Writing about iron arrows, Pliny said, It is a great evil that to enable death to reach human beings more quickly we have taught iron how to fly.

He believed that the nuisance of corrosion compensates for the advantages of the metal because, the same benevolence of nature has limited the power of iron by inflicting on it the penalty of rust, and the same foresight has made nothing in the world more mortal than that which is most hostile to mortality. In other words, Pliny considered the rusting of iron to be a punishment of the gods, as the metal allows itself to be used for swords an other war purposes. A remarkable consequence of his philosophy was the technique of corrosion control by religious ceremony. He recorded that this had been used to protect the chains of a suspension bridge built for Alexander the Great, but Pliny was sceptical because the method had failed on previous occasions.