The first cans were handmade of steel coated with tin. Durand’s early process produced 10 cans per day; modern can-making machines can produce 1000 or more per minutes.
Other innovations include quick-opening cans with pull tabs, as are used for soft drinks, sardines and nuts; cans that are opened with a slotted key that comes with the can, as are used for sardines and cured hams; pasteurized cans that use a propellant to dispense whipped cream and cheese spreads; and extruded or drawn cans, as are used for soft drinks, tuna and sardines.
The extruded cans has several advantages over the conventional can, a major one being the elimination of the bottom and side seams, which reduces the probability of seam failures eliminates the use of lead, (used in side seam) and permits more stable stacking in shelves, requiring somewhat less vertical space.
Two basic types of allowed metals are used in food packaging: steel and aluminium. Steel is used primarily to make rigid cans, where aluminium is used to make cans as well as thin aluminium foils and coatings.
Until a few years ago nearly all steel used for cans was coated with a thin layer of tin to inhibit corrosion; hence, the name ‘tin can’.
Innovation of cans