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A Round Pie in a Square Box

Mismatched pairs of simple things can inspire ingenious solutions

Henry Petroski

Getting a Handle on a Slice

2011-07PetroskiFC.jpgClick to Enlarge ImageKeeping the cheese on the pie is only one problem with hot pizza. Another is getting the first slice out of the box. It is here that the square box actually works to advantage. While a round container would certainly be more geometrically matched to its contents, getting the pizza out of it could lead to considerable frustration, for if the fit were too snug fingers could not easily get under the crust to lift out a slice. With the box square, however, there is ample open space in the corners to get a full hand of fingers underneath the pie. Unfortunately, there can still be another hurdle to overcome before the slice is fully free, for the hot melted cheese tends to flow across the cuts defining the slices, effectively fusing them together in transit to the table. In this case, it can be virtually impossible to lift a slice apart from the rest of the pie without having some undesirable redistribution of cheese between adjacent slices or experiencing the stretching out of long strings of cheese that tie the adjacent slices together. When this happens, it is convenient to have a knife or wheeled cutter handy to sever the connections.

2011-07PetroskiFD.jpgClick to Enlarge ImageSome inventors, like still-life painters who crowd as much onto their canvas as possible, try to solve multiple problems with multipurpose devices crowded with features. Sometimes their inventions succeed; sometimes they do not. One pair of inventors looked to solve the sagging box top and stringy cheese problems with a single device, which they called a “combined pizza box lid support and cutter.” Made of plastic to keep its cost down, the dual-purpose device resembles a rotary cutter but with the wheel’s axle extending to about the height of a delivery box. Another team of inventors received a patent for a “combination food server and container lid support,” which consisted of a pie-slice shaped spatula with its handle offset like that of a mason’s trowel, the amount of the offset being roughly that of the height of the pizza box. (The patent even explained how the device could be inserted into a sliced pizza, so that the blade was under the pie and the handle above it, supporting the top.) Another inventor received a design patent for a combination fork and wheeled cutter, thereby enabling the fastidious pizza eater to cut and spear pieces of pizza without needing two hands free to manipulate a separate knife and fork.

2011-07PetroskiFE.jpgClick to Enlarge ImageAnother team of inventors received a patent in 2007 for what they described as a “lid support and serving aid,” which was embodied in a plastic tripod with one of its legs inclined, elongated and serrated so that it could be used to cut through cheese and crust to produce individual slices. The top platform of the tripod contained a hole large enough for an index finger so that a good grip could be had for executing the cutting process. The platform was also shaped so that individual tripods could be nested like function-room chairs, thus saving shipping and stocking space.

No matter how a slice of pizza is gotten free from its neighbors and from the box they all came in, there can still remain obstacles to neat and comfortable eating. Especially when they are hot, slices of pizza tend to be floppy and so extra care is required in lifting them to the mouth in a configuration that will not encourage cheese to slough off and oil to drip onto the eater’s clothes. A number of inventors have patented pizza boxes with perforated tops and bottoms that allow wedge-shaped pieces of cardboard to be separated from the delivery box to be used as “plates” on which to serve individual slices of pizza. (Some come complete with thumb holes that can be punched out for easier holding.) This reuse of the box not only helps support saggy slices but also encourages the reuse at least of parts of otherwise throwaway boxes.

2011-07PetroskiFF.jpgClick to Enlarge ImageOne traditional way of handling the sagging slice is to bend it along a radial line from tip to crust, effectively creating a trough that gives structural stiffness to the otherwise limp wedge. Interestingly, it is the same structural principle of folding that gives stiffness to the corrugated cardboard box that the pizza comes in and the dimpled paper plate that it is often served on. The principle can easily be demonstrated with a single sheet of paper. Unfolded, it will sag easily when lifted off a pile; folded one or more times—as is done in the process of making a paper airplane—the sheet has considerable stiffness to hold its shape. Achieving stiffness by folding is a ubiquitous technique in structural engineering, being exhibited in everything from corrugated tin roofs to sculpted concrete shells to molded automobile bodies.

The everyday actions of boxing, transporting and delivering a warm pizza, as well as those of separating, serving and eating a slice of the pie, provide familiar examples of how problems are perceived and solutions offered for the engineering and design of complex systems of all kinds. Indeed, anything made and used can serve to illustrate the processes of engineering, invention and design, and the more simple and familiar the thing employed, the more illuminating the example may be.

©Henry Petroski


  • Beck, Dilman A., and Susan E. Beck. 1989. Combination food server and container lid support. U.S. Patent No. 4,877,609.
  • Coomes, Steve. 2004. Thinking ‘round the box. Pizza Marketplace.
  • Fisk, James, Jr. 1995. Pizza box with wedge-shaped break-down spatula-plates. U.S. Patent No. 5,476,214.
  • Maultasch, Jonathan, and Bruce Maultasch. 1996. Combined pizza box lid support and cutter. U.S. Patent No. 5,480,031.
  • Nelson, David C., and John J. Andrisin. 2007. Pizza box lid support and serving aid. U.S. Patent No. 7,191,902.
  • Vitale, Carmela. 1985. Package saver. U.S. Patent No. 4,498,586.
  • Voves, Mark A. 2000. Pizza cutting and eating tool. U.S. Patent No. Des. 425,376.

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