A chemist in France named P. J. Melouin presented a paper to the Royal Academy on a process for dipping steel in molten zinc to protect it from corrosion in 1742. Steel dipped in molten zinc became fashionable for making pots, pans, and kettles that would not corrode over years of use.
This product came to be known as “galvanized” not because of the manufacturing process, but because of the chemical principle that it defined. The scientists of the time recognized that zinc would combine with oxygen in the air more rapidly than iron. The electron had not been discovered, but scientists knew there was some kind of electrical interaction between the zinc coating with oxygen in the air created a zinc oxide coat that protected the iron beneath it. At the time, all kinds of electrical reactions were known as “galvanic,” so zinc-coated steel became known as “galvanized steel.”
In 1824, the British chemist Sir Humphrey Davy discovered that when two different metals were submerged in water and linked by an electrical connection, the corrosion of one would prevent the corrosion of the other. He reasoned that bottoms of wooden naval vessels made from copper could be shielded from corrosion by attaching plates of zinc or iron to them. When copper bottoms were replaced with steel, they could also be protected by zinc. This observation propelled the galvanizing process into industrial prominence after two more inventions made using it possible.
In 1836 that French engineer Stanislaus Tranquille-Modeste Sorel took out a patent on the galvanizing process. Prior to Sorel, untreated steel was simply dipped in molten zinc to galvanize it. Sorel’s innovation was to clean it in a diluted solution of water and sulfuric acid and fluxing it with an alkali, typically ammonium chloride, to make it the iron even more resistant to oxidation by the air, and only then dipping it into molten zinc. The very next year, in 1837, British inventor William Crawford was granted a patent for a related process.
