In 1837, French alchemist Stanislaus Sorel patented a type of paint-on coating made from the element zinc. When iron was dipped into the molten zinc, it resulted in a pitted, silvery coating that protected the iron from corrosion.
Sorel called this process “galvanization.” The word already existed … and meant something completely different. The name stuck, however. “Galvanized” steel, hot-dipped in liquid zinc, is a common material used for many industrial purposes.
The use of zinc in metalwork dates back over 3,000 years. Judean brass crafts produced between the 14th and 9th Centuries B.C. were discovered to contain 23% zinc. Ornaments containing up to 80% of the brittle metal date back to 2,500 years.
Zinc has also been used as medicine for thousands of years. The 6th-Century-B.C. Indian medical text Charaka Samhita describes pushpanjan (“philosopher’s wool”), a cream made from oxidized metal used to treat open wounds and irritated eyes. Philosopher’s wool was most likely zinc oxide. The first known zinc pills were used by Roman mariners to treat sore eyes, discovered in shipwrecks dating back to the 2nd Century B.C.
China adopted zinc manufacture in the 17th Century A.D. The first European zinc smelting facility was established in Bristol, England in 1743.
In 1780, Italian scientist Luigi Galvani discovered that he could induce a frog’s leg to twitch when he pressed two dissimilar metals (iron and copper) against the leg simultaneously. Galvani correctly induced that muscular contraction resulted from an electrical stimulus. Further, the metals induced electrical currents in the frog’s leg that caused the muscles to involuntarily flex.
The term “galvanize” came to mean “to shock or incite to action.” It became associated with the work of Michael Faraday, the father of modern electromagnetics, and Alessandro Volta, inventor of the battery and namesake of the term “voltage.”
In 1824, Sir Humphrey Davy discovered by connecting two metals electrically and submerging them in water, one metal corroded faster while the other corroded slower. This was the invention of “cathodic protection” — grafting a “sacrificial” metal to a metal structure as an “anode,” slowing the corrosion of the structural metal.
At the time, the bottoms of wooden ships were reinforced with copper, which corroded easily. Davis suggested that cathodic protection be deployed to protect the copper components. The chosen materials? Plates of iron and zinc. When steel and iron replaced wood in ship construction, zinc anodes were still used to slow the corrosion of the hull.
A French chemist named Melouin presented a paper to the French Royal Academy in 1742 describing the dipping of iron into molten zinc as a protective coating, sparking interest in the scientific community.
When Sorel patented his process of dipping metal in zinc, he knew the common-usage meaning of “galvanization.” The zinc does not stimulate the steel into action, but it does serve a “sacrificial” role in protecting the coated metal, like the anode metal in cathodic protection.
A British patent was issued for a similar process to William Crawford in 1837. Galvanized iron is believed to have first been used by the British Navy on Pembroke Docks in 1944. By 1850 the British galvanizing industry consumed 10,000 tonnes of zinc per year and “galvanized” entered the public lexicon, irrevocably tied to the engineered steel product.
In the First World War, an American-born engineer serving with the Royal Engineers at Ypres invented the Nissen Hut. The inexpensive, hardy, easy-to-erect structure featured an arched roof structure made of corrugated galvanized steel. Nissen Huts played a large role in both World Wars. The splotchy texture of galvanized steel came to symbolize the hardships and perseverance of 20th-Century warfare.
Today, the North American galvanization industry alone consumes 600,000 tons of zinc per day. Galvanized steel plays a key role in multiple industries. Manufacturers of street lamps, high-voltage pylons, outdoor furniture, transportation infrastructure, and fastenings all use galvanized steel extensively. Other uses include utilities, storage and handling, agriculture and horticulture, and industrial equipment and plants.
Hot-dipped galvanization costs less than anti-corrosive paint solutions. Zinc is recyclable and highly sustainable, essential for the human body and global ecology. Galvanized steel distinguishes itself as a building and manufacturing material for its versatility, durability, economy, eco-friendliness, and aesthetic appeal.