On this Wikipedia the language links are at the top of the page across from the article title. This article is about a method of food preservation. For the casino, see Cannery Casino canning crisp banana peppers Hotel.

For the thermochemical decomposition of organic material, see Pyrolysis. Not to be confused with Caning. In 1974, samples of canned food from the wreck of the Bertrand, a steamboat that sank in the Missouri River in 1865, were tested by the National Food Processors Association. This section needs additional citations for verification.

Please help improve this article by adding citations to reliable sources. During the first years of the Napoleonic Wars, the French government offered a hefty cash award of 12,000 francs to any inventor who could devise a cheap and effective method of preserving large amounts of food. The larger armies of the period required increased and regular supplies of quality food. Limited food availability was among the factors limiting military campaigns to the summer and autumn months. The French Army began experimenting with issuing canned foods to its soldiers, but the slow process of canning foods and the even slower development and transport stages prevented the army from shipping large amounts across the French Empire, and the war ended before the process was perfected. Following the end of the Napoleonic Wars, the canning process was gradually employed in other European countries and in the US.

A Dixie Can Sealer for home use. Now in Thinktank, Birmingham Science Museum. Based on Appert’s methods of food preservation, the tin can process was allegedly developed by Frenchman Philippe de Girard, who came to London and used British merchant Peter Durand as an agent to patent his own idea in 1810. The main market for the food at this stage was the British Army and Royal Navy. 3000 worth of canned meat in six months. During the mid-19th century, canned food became a status symbol among middle-class households in Europe, being something of a frivolous novelty. Early methods of manufacture employed poisonous lead solder for sealing the cans.

Increasing mechanization of the canning process, coupled with a huge increase in urban populations across Europe, resulted in a rising demand for canned food. A number of inventions and improvements followed, and by the 1860s smaller machine-made steel cans were possible, and the time to cook food in sealed cans had been reduced from around six hours to thirty minutes. Robert Ayars established the first American canning factory in New York City in 1812, using improved tin-plated wrought-iron cans for preserving oysters, meats, fruits and vegetables. Demand for canned food skyrocketed during World War I, as military commanders sought vast quantities of cheap, high-calorie food to feed their millions of soldiers, which could be transported safely, survive trench conditions, and not spoil in transport. Please expand the section to include this information. Further details may exist on the talk page.

Cans are cheaper and quicker to make, and much less fragile than glass jars. Today, tin-coated steel is the material most commonly used. Glass jars have remained popular for some high-value products and in home canning. Other than sterilization, no method is perfectly dependable as a preservative. To achieve temperatures above the boiling point requires the use of a pressure canner. Invented in 1888 by Max Ams, modern double seams provide an airtight seal to the tin can. This airtight nature is crucial to keeping micro-organisms out of the can and keeping its contents sealed inside.

Double seaming uses rollers to shape the can, lid and the final double seam. To make a sanitary can and lid suitable for double seaming, manufacture begins with a sheet of coated tin plate. To create the can body, rectangles are cut and curled around a die, and welded together creating a cylinder with a side seam. Rollers are then used to flare out one or both ends of the cylinder to create a quarter circle flange around the circumference. Precision is required to ensure that the welded sides are perfectly aligned, as any misalignment will cause inconsistent flange shape, compromising its integrity.

A circle is then cut from the sheet using a die cutter. The circle is shaped in a stamping press to create a downward countersink to fit snugly into the can body. The result can be compared to an upside down and very flat top hat. The outer edge is then curled down and around about 140 degrees using rollers to create the end curl. The result is a steel tube with a flanged edge, and a countersunk steel disc with a curled edge.

A rubber compound is put inside the curl. The body and end are brought together in a seamer and held in place by the base plate and chuck, respectively. The result is the countersink of the end sits inside the top of the can body just below the flange. The end curl protrudes slightly beyond the flange.