Tin Can Day

What the day is

Tin Can Day is observed on January 19, associated with the 1810 British patent granted to Peter Durand for preserving food in sealed metal canisters.

Origin and background

The science came first and nobody understood it. A French confectioner, Nicolas Appert, had worked out that food sealed in glass and heated would keep, and won a prize from the French government for it in 1810. This was half a century before germ theory. Appert knew the method worked and had no idea why, and the explanation, that heating destroyed the microorganisms causing spoilage, only arrived with Pasteur decades later. Canning is one of the clearer cases of a technology running well ahead of the science that justifies it.

Durand's contribution was the container: metal instead of glass, which survived transport and suited armies and navies, the first serious customers.

Then comes the famous gap. The can opener was not invented until the 1850s. For roughly forty-odd years, cans were opened by whatever came to hand, and early labels instructed the buyer to cut around the top with a chisel and a hammer. The cans of the period were thick enough that this was not unreasonable, and it was only as manufacturing thinned the walls that a dedicated tool became practical.

The name is also misleading. A tin can is steel with a thin tin coating, applied because tin resists corrosion and does not react with food. The steel does the structural work.

Modern cans are lined on the inside, which prevents metal contact with acidic contents, and the composition of that lining has been the subject of long-running debate over the plastics used in it.

How to take part

• Check the date on the oldest can in your cupboard, which is probably still fine.
• Recycle them, since steel recycles indefinitely without losing quality.
• Never use a can that is bulging or hissing, which is the one genuine danger sign.
• Look up an early can opener design, which looks like a weapon.
• Read about Appert, who solved the problem without knowing what the problem was.