The Evolution of the Soda Can Tab

Tom Vanderbilt, writing for Slate, traces the very interesting history of soda tab design. The modern incarnation of the ubiquitous feature has only been in existence for less than 40 years:

The solution came from Daniel F. Cudzik, an engineer with Reynolds Metals, who for years had been toiling away on what would what become known as the “Sta-Tab.” As Cudzik told Studio 360, his search for a “convenience top” that was “more practical and less prone to litter” came to fruition one night when he was in living room, “half watching a movie.” While the idea might seem simple to a consumer raised on nothing but stay-on tabs, the design required some elegant engineering (and some subsequent legal battles over alleged patent infringements).

As Cudzik described the problem in his 1975 patent application: “The opening construction of the invention requires a tab which must be stiff against transverse bending and yet flexible enough and tough enough at the connection between the tab end wall to permit lifting and retracting the tab without causing a fatigue crack at the connection.” As elegantly explained in this video, the design operates both as a “second class” and as a “first class lever” at different points in the can-opening process—redirecting loads and shifting the fulcrum—using the inherent pressure from the carbonated beverage in its favor.

Apparently the new invention caused some concern, as people were used to opening cans with this device.

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