History of Steel

In 1810, an Englishman named Peter Durand was granted a patent from King George III for the idea of preserving food in "vessels of glass, pottery, tin or other metals or fit materials." Durand intended fashion containers out of tinplate. Made of iron coated with tin to prevent rusting and corrosion, tinplate could be sealed and made airtight but was not breakable like glass. A cylindrical canister and soldered lid would be much easier to handle than a fragile bottle with an unreliable cork.

Two other Englishmen, Bryan Donkin and John Hall, used Durand's patent and, after more than a year of experimentation, set up the first commercial canning factory using tinplate cans in Bermondsey, England in 1812. If the French military was to travel farther and longer on their provisions, then the British needed to be able to do so as well. By 1813, Donkin's tins of preserved food were supplying the British army and navy. The Royal Navy used as many as 24,000 large cans—nearly 40,000 pounds—on its ships each year by 1818. The nutritious canned vegetables were a great relief to sailors who previously had relied on live cargo or salted meat and were often plagued by debilitating scurvy. It was believed that the salt caused the condition, when it was actually because the salt-cured foods lost most of their vitamins and nutrients in the preservation process.

"Hole and cap" can, c. 1889-1919
C.W. Swaim Canning Co

The earliest cans were laboriously made by hand. Iron was pounded into sheets and dipped into molten tin. The resulting tinplate was then soaked in brine baths, creating a hot and odorous atmosphere. Using considerable skill and muscle, artisans cut the sheets into rectangular bodies and round ends. The body pieces were bent around a cylindrical mold and the seams and ends were soldered in place. One of the ends was made with a circular hole through which the food would be stuffed. Once filled, the holes were plugged with a soldered metal cap. This soldering process sometimes left a bit of soot mixed in with the can's contents.

This process allowed even the most skilled workers to only make about ten cans per day. Eventually mechanization and the invention of the "sanitary can" sped these processes. The "sanitary can" folds the edges of the can and ends over twice, forming a strong seal. This method eliminated the need for the hole and cap method of filling as well as the residual soot from soldering. Mechanical body makers, industrial die cutting, and machine-pressed tinplate all improved can making during the early part of the century.

Today there are more than 600 sizes and styles of cans being manufactured. The amount and combination of tin and steel used to form the tinplate varies as well, depending upon the function of the can. The tin coating is usually as thin as a human hair, but still serves to protect the can inside and out against rusting. Protective coatings applied to the inside of the cans also ensure the integrity of the contents and have allowed cans to hold many products, such as citrus fruits, which would otherwise be too corrosive. Tin-free steel and aluminum have added even more flexibility and versatility to the modern day can line.