In 1810, Napoleon Bonaparte offered a prize for anyone who could devise a method to preserve food. Nicholas Appert, a French chef, found that cans hermetically sealed with solder kept food preserved for some time, but these were heavy and expensive. In 1855, Robert Arthur found that cans could be sealed with wax instead of solder – easier to open, but still awkward. These methods were applied to glass containers as they became more widely available. Then in 1858, twenty-six-year-old John L. Mason invented the screw-top jar. This was a huge improvement, as it made for reusable jars and tops. His jars had threads molded into them, and his lids had a rubber ring to make the seal. Mason jars became a standard item of the late 19th century, allowing households to store the foods they had grown or made for months or years. Canning became a standard activity in households until the wide availability of processed foods in and after the 1950s.