Home Canning Canning A dished distortion (or waviness) in a flat or nearly flat surface sometimes referred to as “oil canning.” It is an inherent characteristic of light-gauge, cold-rolled flat metal products and can occur in any type of metal material used in construction including steel, copper, zinc and aluminum. The severity of the distortion is dependent on the colour, finish, time of day, time of year or the viewing angle ─ a reason why there is no true way to measure it. The causes for canning vary but the most common explanations include: Stress during production/milling process Incorrect handling Thermal expansion and contraction < Glossary
