Metal Canning, Metal cans and glass jars being heat resistant, can both be used for heat processed, wet-pack foods and for non-heat treated dry pack canning.

Metal cans are not entirely made of tin. They are actually steel cans with a tin coating on the inside and outside. Certain darker acidic foods can discolor from prolonged exposure to tin, so an enamel lining called “R-enamel” is used to prevent this from happening.

Certain other types of foods that are high in sulfur or near-neutral PH can also discolor from prolonged exposure to tin. For these foods, use cans with “C-enamel”.