By The Metric Maven

Bulldog Edition

My father once worked in a corn canning factory, and has many tales from his tenure there. The one story which always comes to mind is that of a co-worker, called Roscoe, who marched to a different, and rather stochastic drummer. Roscoe never seemed to be able to get his time card to remotely match his apparent work schedule. One day his boss blew his top after seeing Roscoe’s time card and demanded he immediately come into his office. The boss looked at Rosco and inquired about the entries on his time card.

Boss: I’ve looked at your card for this week and on Wednesday it indicates you worked 25 hours on that day.

Roscoe: Yeah.

Boss: Roscoe, could you please explain to me how you could possibly have worked 25 hours on Wednesday.

Rosco: I didn’t take lunch that day.

It was tales like that which made me believe that the canning plant was operated by a mad hatter, with help from Bizzaroworld.

Recently my father sent me this table from a new cookbook:

How could I help but wonder if Roscoe had been tasked with determining the can nomenclature and quantity. An eight ounce can is 1 cup, which makes as much sense as any of the Ye Olde English Arbitrary Grouping of Weights and Measures do. Who would have thought that the next size up from an eight ounce can would be a picnic sized can? Every Midwestern picnic I’ve ever attended would always have cans of Van Camp’s Pork and Beans, “freshly opened” for the occasion, right in front of my eyes. Their website indicates the available cans are in 8 oz, 15 oz, 31 oz, 53 oz, and 114 oz sizes. Well, the cookbook has the wrong table so we’ll re-write it to conform with the VCPB default units:

Contents of Standard Cans:

8 oz Can = 8 ounces

Picnic = 10 ounces

No. 300 = 14 ounces

No. 1 tall = 16 ounces

No. 303 = 16 ounces

No. 2 = 20 ounces

No. 2 1/2 = 28 ounces

No. 3 = 32 ounces

No. 5 = 58 ounces

No. 10 = 80 ounces

The cookbook only matches one value of VC Pork and Beans. They do not have a “picnic” size can. How on earth was I able to go on all those picnics? Was it a massive cover-up by the well-meaning women of my childhood? My father indicated that the corn canning plant at which he worked, exclusively used No. 303 cans. But how would he know if someone slipped some contraband No. 1 tall cans into the to loading dock?

Among my eclectic collection of books about engineering and science, I have zero references on standard sized “tin cans.” Wikipedia, as usual does not disappoint, and has a section on standard sizes. I’m sure the diligent volunteers there can clear up the confusion:

Can sizes in the United States have an assortment of designations and sizes. For example, size 7/8 contains one serving of half a cup with an estimated weight of 4 ounces; size 1 “picnic” has two or three servings totalling one and a quarter cups with an estimated weight of 10½ ounces; size 303 has four servings totalling 2 cups weighing 15½ ounces; and size 10 cans, most widely used by food services selling to cafeterias and restaurants, have twenty-five servings totalling 13 cups with an estimated weight of 103½ ounces (size of a roughly 3 pound coffee can). These are all “U.S. customary” cups, and not equivalent to the former Imperial standard of the British Empire or the later Commonwealth.

Wait a minute? The picnic size has 1 1/4 cups, which the last time I checked my Ye Olde English references was volume, which would translate into 10 fluid ounces, but it is designated as about 10 1/2 weight ounces? My understanding is that one fluid ounce of water = 1.0425 avoirdupois ounces more or less, so 10 fluid ounces of water is approximately 10.425 weight ounces. This is the picnic size which has an estimated weight of 10.5 ounces. This assumes the density of beans is the same as the density of water.

Apparently this means I should have written the table:

8 oz Can = 8 fluid ounces = 8.34 ounces

Picnic = 10 fluid ounces = 10.43 ounces

No. 300 = 14 fluid ounces = 14.59 ounces

No. 1 tall = 16 fluid ounces = 16.68 ounces

No. 303 = 16 fluid ounces = 16.68 ounces

No. 2 = 20 fluid ounces = 20.85 ounces

No. 2 1/2 = 28 fluid ounces = 29.19 ounces

No. 3 = 32 fluid ounces = 33.36 ounces

No. 5 = 58 fluid ounces = 60.46 ounces

No. 10 = 80 fluid ounces = 84.4 ounces

When Van Camp’s gives their can sizes in ounces, is it fluid ounces or weight ounces?—with avoirdupois assumed? Perhaps Wikipedia can shed more light into this morass:

In the United States, cook books will sometimes reference cans by size. These sizes are currently published by the Can Manufacturers Institute and may be expressed in three-digit numbers, as measured in whole and sixteenths of an inch for the container’s nominal outside dimensions: a 307 x 512 would thus measure 3 and 7/16″ in diameter by 5 and 3/4″ (12/16″) in height. Notice that this is not in millimetres. Older can numbers are often expressed as single digits, their contents being calculated for room-temperature water as approximately eleven ounces (#1 “picnic” can), twenty ounces (#2), thirty-two ounces (#3) fifty-eight ounces (#5) and one-hundred-ten ounces (#10 “coffee” can).[9]

Ok, so “new” cans are all given as a volume of the outside of the can in 1/16 inch increments, but the “old” can numbers relate to the weight of room-temperature water? As the rest of the world might actually think we in the US did something rational with a measurement, they have to warn them that the can numbers do not relate to millimeters.

The Can Manufacturers Institute has this to say:

The CMI Voluntary Can and End Dimension Reference Manual is a compilation of technical information developed by committees of the Can Manufacturers Institute (CMI). Intended for use by CMI members and other interested industry representatives, this publication is available to the public as a service of the Can Manufacturers Institute. CMI does not provide either an expressed or implied warranty as to their viability or accuracy.

Ah, yes, following long established US tradition, the values provided by industry are all voluntary and they are not to be held responsible if the values are not used or met or whatever. How dare you think they might be held to measurement standards. Here are the very, very, voluntary values:

So what values are used in metric countries? According to Wikipedia:

In countries and regions that use the metric system of measures, most tins are made in 250, 500, 750 ml (millilitre) and 1 L (litre) sizes (250 ml is approximately 1 cup or 8 ounces). In situations where products from the USA have been repackaged for sale in such countries, it is common to have odd sizes such as 3.8 L (1 USA gallon), 1.9 L (1/2 USA gallon), and 946 ml (USA 2 pints / 1 quart).

In metric countries one would expect volume in milliliters and/or mass in grams. Both would be very good. My pantry shelf indicates that cans of beans and sauces in the US are all given in weight, so the only two values on the label are in weight in ounces and mass in grams. Therefore one much ask a simple question: “why did the cookbook offer the contents in cups?–which are clearly volume—when they are sold by mass?” The simple answer is I don’t know, and I doubt they would have a rational answer either. The designation of cans in the US is archaic, irrational and yet again shows that leaving the magic of technical Darwinism to determine the labeling of quantities in our economy only produces a chaotic situation which only confuses and does not offer clarity. Because this is the case, we are only left peering into an an open can of worms because we have never had a mandatory metric system switch-over in the US.

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