The Pull-Tab Can Fixed One Problem and Created a Litter Crisis

US3349949 was granted to Ermal Cleon Fraze on October 31, 1967. It covers the pull-tab opening for beverage cans, and the story behind it is the kind of small domestic humiliation that produces good engineering.

Before the pull tab, opening a can of beer or soda required a separate tool — the "church key," a pointed lever that punched a triangular hole in the lid, plus a second hole opposite for air. If you did not have one, you improvised, badly.

At a family picnic in 1959, Fraze — who owned Dayton Reliable Tool, a machine shop in Ohio — found himself without a church key. The commonly repeated account has him opening cans against the bumper of his car, which worked in the sense that the beer came out and did not work in most other senses.

The riveted tab

The engineering problem is more subtle than it looks. A can lid must be thin enough to tear open by hand along a controlled line, yet strong enough to contain carbonation pressure without leaking or bursting, and it must be mass-produced at a rate of hundreds per minute for a fraction of a cent.

Fraze's solution had two key pieces. First, a scored line pressed into the lid — a groove thin enough to tear predictably but not thin enough to fail under pressure. Second, and critically, a rivet formed from the lid metal itself, made by pushing up a small button of the aluminum and folding it over to secure the tab. Attaching the tab with a separate fastener would have added cost and a leak path; forming it from the lid solved both at once.

Fraze's tabs went onto Iron City Beer in Pittsburgh in 1962, and within a few years essentially the entire American beverage industry had converted.

The unintended consequence

The original design was a pull-off tab: it detached completely and came away in your hand. Hundreds of millions of cans a year meant hundreds of millions of small, sharp aluminum tabs, and people dropped them wherever they were standing.

Through the late 1960s and 1970s the tabs became an emblem of the era's litter problem — scattered across beaches, parks, roadsides, and campgrounds. Worse, they were a genuine injury hazard: sharp enough to cut bare feet, and small enough that people occasionally dropped them into the can and swallowed them.

Jimmy Buffett's "Margaritaville," recorded in 1977, contains the line about stepping on a pop-top and cutting a heel — a small piece of evidence about how ordinary the injury was.

The industry's fix was the stay-on tab, developed largely by Daniel F. Cudzik at Reynolds Metals in the mid-1970s. Instead of detaching, the tab levers a scored panel downward into the can and remains riveted to the lid. It is the design still in use today, and it eliminated the loose-tab problem essentially overnight as it was adopted.

The whole arc — a good invention, a large unforeseen externality, a second invention to fix it — took about fifteen years, and left behind an object so ordinary that almost nobody notices it was designed at all.

The pull tab was the last move in a long argument about how to get into a sealed metal container. The argument started badly: the tin can went 48 years with no opener at all.

See the original

The full text and figures of US3349949 are on patents.us.