Early metal drink cans had no tabs; they were opened by a can-piercer or
churchkey, a device resembling a
bottle opener with a sharp point. The can was opened by punching two triangular holes in the lid—a large one for drinking, and a second smaller one to admit air. As early as 1922, inventors were applying for patents on cans with tab tops, but the technology of the time made these inventions impractical. Later advancements saw the ends of the can made out of aluminum instead of steel. In 1959,
Ermal Fraze devised a can-opening method that would come to dominate the canned drink market. His invention was the "pull-tab". This eliminated the need for a separate opener tool by attaching an aluminum pull-ring lever with a rivet to a pre-scored wedge-shaped tab section of the can top. The ring was riveted to the center of the top, which created an elongated opening large enough that one hole simultaneously served to let the drink flow out while air flowed in. Previously, while on a family picnic, Fraze had forgotten to bring a can opener and was forced to use a car bumper to open a can of beer. Thinking there must be an easier way, he stayed up all night until he came up with the pull tab. Pull-tab cans, or the discarded tabs from them, were colloquially called "pop-tops". Into the 1970s the pull-tab was widely popular, but its popularity came with the problem of people frequently simply discarding the pull-tabs on the ground, creating a potential injury risk especially to the feet or fingers. In the 1960s, at least one inventor attempted to solve the litter problem, by having the tab be retained by a stationary key that would wrap the tab around itself, which was unsuccessful commercially. The problem of the discarded tops was initially solved by the invention of the push-tab. Used primarily on
Coors Beer cans in the mid-1970s, the push-tab was a raised circular scored area used in place of the pull-tab. It needed no ring to pull up; instead, the raised aluminum blister was pushed down into the can using one finger. A small unscored section of the tab prevented it from detaching and falling into the can after being pushed in. Push-tabs never gained wide popularity because while they had solved the
litter problem of the pull-tab, they created a safety hazard where the person's finger upon pushing the tab into the can was immediately exposed to the sharp edges of the opening. A feature of the push-tab Coors Beer cans was that they had a second, smaller, push-tab at the top as an airflow vent. "Push-tabs" were introduced into Australia from around 1977 and were locally known as "pop-tops", before being replaced later by the Stay-on-tab. The safety and litter problems were eventually solved later in the 1970s with Daniel F. Cudzik's invention of the non-removing "Stay-Tab". Cans are usually in sealed
paperboard cartons,
corrugated fiberboard boxes, or trays covered with plastic film. The entire distribution system and packaging need to be controlled to ensure freshness.
Pop-tab in Beijing, China in 2009|upright=0.5 In 1962,
Ermal Cleon Fraze of
Dayton, Ohio, United States, invented the integral rivet and pull-tab version (also known as
ring pull in
British English), which had a ring attached at the rivet for pulling, and which would detach completely to be discarded. He received US Patent No. 3,349,949 for his pull-top can design in 1963 and licensed his invention to
Alcoa and
Pittsburgh Brewing Company, the latter of which first introduced the design on
Iron City Beer cans. The first soft drinks to be sold in all-aluminum cans were
R.C. Cola and
Diet-Rite Cola, both made by the
Royal Crown Cola company, in 1964. The early pull-tabs detached easily. In 1976, the
Journal of the American Medical Association noted cases of children ingesting pull-tabs that had broken off and dropped into the can. Full-top pull-tabs were also used in some
oil cans and are currently used in some
soup,
pet food,
tennis ball,
nuts, and other cans.
Stay-on-tab In 1958, American inventor
Anthony Bajada was awarded the patent for a "Lid closure for can containers". Bajada's invention was the first design to keep the opening tab connected to the lid of the can, preventing it from falling into the contents of the can. His patent expired in 1975 and has been directly cited in the mechanisms used by companies such as
Crown Cork & Seal Co.,
BHP, and
United States Steel Corporation. Approximately one month after Bajada's patent expired, Daniel F. Cudzik, an engineer with
Reynolds Metals, filed a design patent application for an "End closure for a container". This later became known as a "Sta-Tab". When the Sta-Tab launched in 1975, on
Falls City beer and, quickly, other drinks, there was an initial period of consumer testing and education. Cudzik later received patents for this "Easy Open Wall" ( ). The validity of these patents was upheld in subsequent litigation. The similarly designed "Easy-open ecology end" was invented by
Ermal Fraze and Omar Brown. Its patent application was also filed in 1975, less than two months after the expiration of Bajada's patent. This design, like Cudzik's, uses a separate tab attached to the upper surface as a
lever to depress a
scored part of the lid, which folds underneath the top of the can and out of the way of the resulting opening, thus reducing injuries and roadside litter caused by removable tabs. Such "retained ring-pull" cans supplanted pull-off tabs in the
United Kingdom in 1989 for soft drinks and 1990 for
alcoholic drinks. The stay-on-tab (SOT) opening system solved the environmental issue of the previous pull-tab design. However, it introduced a new, still unresolved hygiene concern: the outer panel of the tab now sinks into the liquid inside the can. One of the more recent modifications to can design was the introduction of the "wide mouth" can in the late 1990s. The
American Can Company, now a part of
Rexam, and
Coors Brewing Company have owned wide mouth design patent (number D385,192) since 1997. Other companies have similar designs for the wide mouth.
Ball Corporation's from 2008 has a vent tube to allow direct airflow into the can reducing the number of gulps during the pour. Current SOT opening systems have a great deal of embedded design and engineering for them to open consistently and to avoid injury. In addition to the scored part of the lid, there is an
indentation in the lid over one of the scored lines which points to the other scored line. This indentation localizes the applied stress from lifting the tab and acts as a stress shield to apply a critical amount of localized stress to fracture the aluminum along the scored line. The crack that is initiated grows in two directions: back toward the tab and around a crack arresting feature, and then around the perimeter of the opening to the other end of the scored line where the crack stops--the metal between the crack arresting shape and the end of the crack acts as a plastic hinge to allow the tab to push the opening of the can away from where the liquid is consumed.
Press button can One variation was the press button can, which featured two pre-cut buttons—one small and one large—in the top of the can sealed with a plastic membrane. These buttons were held closed by the outward pressure of the
carbonated drink. The consumer would open the can by depressing both buttons, which would result in two holes. The small hole would act as a vent to relieve internal pressure so the larger button could then be pressed down to create the hole used for consuming the drink. Consumers could also easily cut themselves on the edges of the holes or get their fingers stuck. Press button cans were used by Pepsi in
Canada from the 1970s to 1980s and
Coors in the 1970s. They have since been replaced with pull tabs. Used in Australia, locally known as "pop-tops", for soft drinks from 1977 to the early 1980s. However, Heineken Brewery did bring back press- or push button cans on the market in Europe as a short-lived marketing strategy in the 1990s.
Full aperture end uses "topless" cans where the entire lid is removed when opening the can.|upright=0.5 Another variation on the drink can is the "full aperture end", where the entire lid can be removed – turning an aluminum can into a cup.
Crown Holdings first designed the "360 End" for use by
SABMiller at the
2010 FIFA World Cup in
South Africa. It has been used by
Anheuser-Busch InBev in
China and
Brazil and by the
Sly Fox Brewing Company in the United States.
Resealable lid Another variation on the drink can is to have a resealable lid. A version patented by Cogito Can in France has been used by Groupe Casino, the French grocery chain for its private label energy drink. == Recycling ==