The process of sealing cans changed several times as canners sought the most efficient and safest way to preserve their product.
During the first decade of the industry, Chinese workers used a soldering iron to seal the seams of the can with lead solder. By the 1880s, soldering machines mechanized this process by rolling cans on a conveyer through an angled trough filled with molten lead solder.
Sanitary cans were introduced in 1912. They were called sanitary because they did not require lead solder to attach the tops and bottoms. Lids were fastened on with a double seamer which secured the lids with a double fold.
Introduced in the 1920s, the vacuum closing machine sealed the cans inside a vacuum chamber. Manual labour was drastically reduced, as only one worker was required to ensure the machine was stocked full of lids.