Form Follows Failure
In 1809, after years of experimenting, a Parisian confectioner named Nicolas Appert demonstrated a scheme for putting cooked fruit, vegetables, and meat in cork-sealed bottles and then immersing the bottles in boiling water, which, as we now know, destroyed the bacteria that could ruin the contents. For developing his method of food preservation, Appert was granted 12,000 francs by the French government, and in 1810 he published a book, L’Art de Conserver , that was soon translated into several languages.
Bottles were breakable, of course, and this was a distinct disadvantage of Appert’s scheme. Peter Durand, a London merchant, eliminated that drawback by devising a sealed tin canister, and the firm of Donkin and Hall soon set up a “preservatory” near London, employing the new tin cans. Innovators like Durand apparently focused so extensively on preserving food against spoiling that they gave little thought to how it might be removed from the tin. It is the rare invention that does not cause an infrastructure of auxiliary inven, tions to follow as failures inherent in the design or even created it keep presenting themselves.
Soldiers reportedly had to attack their canned rations with knives, bayonets, and even rifle fire, as American Civil War troops still would a half-century later. If Donkin and Hall wanted to sell their products to a broader clientele, they would certainly have to address the problem of how civilly to get what was inside a can out, but as late as 1824 a tin of roast veal carried on one of William Parry’s Arctic expeditions bore the instructions “Cut round on the top near to the outer edge with a chisel and hammer.”
Nonetheless, British shops were selling canned food to the public by 1830, and the Englishman William Underwood, who established an early cannery in Boston, apparently spoke for all his contemporaries when he advised using whatever tools might be available to open tin cans in any makeshift way. For all its need, no specialized tool was to be forthcoming for quite some time. In the meantime, early cans of heavy-gauge iron could be heavier than the food they contained. That can of veal taken to the Arctic weighed more than one pound empty, and its wall was about a fifth of an inch thick.
Appreciating these shortcomings, some inventors concentrated on ways to make cans thinner, lighter, and more easily assembled and disassembled, while others tackled the problem of developing specialized tools for opening them. The replacement of iron with the stronger material steel in the late 1850s meant that a thinner can could be produced, but the greater flexibility of the lighter material in turn necessitated the introduction of a rim for stiffening and for attaching a top and bottom, which in earlier times had been folded over onto the can’s sturdy sides. (Today many steel cans are corrugated under their paper labels to further stiffen them against being dented during handling.)
In 1858 Ezra Warner, of Waterbury, Connecticut, obtained a landmark patent for a can opener, which was described by one student of the origins of everyday things as “part bayonet, part sickle, [with a] large curved blade.” Like inventors before and after him, Warner defended his brainchild by comparing it with its more primitive, unsatisfactory predecessors: “The advantages of my improvement over all other instruments for this purpose consist in the smoothness and rapidity of the cut, as well as the ease with which it is worked, as a child may use it without difficulty, or risk, and in making the curved cutter susceptible of being removed, so that if one should be injured it may be replaced by another, thus saving all the other portions of the instrument, and consequently much expense, and in that the piercer will perforate the tin without causing the liquid to fly out, as it does in all those which make the perforation by percussion of any kind.”
Such devices saw some use during the Civil War, but soldiers and homemakers alike tended to keep opening cans with implements with which they had long been familiar. Not until 1885 did the British Army and Navy Co-operative Society, whose catalogue was an omnium-gatherum of Victorian gadgets and merchandise, offer its first can opener. Anyone who has used an old-fashioned can opener, with a pointed blade, knows all the disadvantages of the tool. Its action is jerky rather than continuous, and it leaves behind a hazardous jagged edge. The first opener with a wheel, for continuous and smooth cutting, was apparently patented in America in 1870 by William Lyman, of West Meriden, Connecticut. One end of the opener pierced the center of a can’s top and served as a pivot about which the handle pulled a cutting wheel. The device had to be adjusted for each size can, and its efficient operation relied upon getting a bull’s-eye with the piercer.
In 1925 a patent was issued for an improvement on what has become a familiar style of wheeled opener, the kind that pinches and rides around the rim of the can. The improvement employed a serrated wheel to reduce the slippage. Today, of course, there is a great variety of can openers, some of them electric, but every one has its drawbacks or little annoyances. Those that work with a squeeze of the handle and a twist of the wrist can be tiring to use on large cans and frustrating when their driving wheel slips rather than grips the can. Electric can openers can be bulky, counter-cluttering, and difficult to clean. Almost two centuries after the introduction of tin cans there is still room for improvement in the equipment to break into them, and thus there are likely to continue to be inventors patenting new openers. In the meantime, of course, pull-opening tops are being incorporated into more and more cans, and so developing a better can opener may become moot.
Beverage cans were at first not much different from food cans. They were formed from three pieces of tin-plated steel: one rectangular piece bent into a hollow cylinder and welded along its seam and two disks for the top and bottom. The can still required an opener, but since the contents were liquid, the opener had only to make a hole large enough for a pouring spout. Anyone who tried to open a can of beer with an old-fashioned food-can opener would likely have sloshed the contents all over the place and risked a jagged lip first of steel and then of flesh. Thus that specialized opener known as the church key was developed to pierce the pressurized can with minimum jolting and leave a wedge-shaped hole. Some early beer cans intended to be opened with the new device carried illustrated directions.
Ideally, a single pie-slice wedge that extended to the center of the can top could be cut in a single motion and allow air to enter the can just above the drinker’s upper lip. But because early beer cans had relatively heavy steel tops, the applied mechanics of the opener dictated that it make a much smaller wedge-shaped opening close to the edge of the can.
The church key is a simple lever whose fulcrum hooks under the top lip of the can. The handle extending outward from the can provides one arm of the lever, the pointed cutting edge extending over the can top, the other. As with all levers, the length of the handle magnifies the effect of the force applied to its end, but by the same token the piercing force diminishes as the distance from the fulcrum to the tip of the cutting edge increases. So to make a church key that is not too long, yet can pierce the can top without being bent out of shape, a compromise opener was developed that produced a relatively small hole close to the can’s edge. Drinking beer through such a hole is only slightly less objectionable than drinking it through a straw, and pouring it is a slow, gurgling procedure. Thus a venting hole on the opposite side of the top is now customarily made with the church key. (Homemakers were used to making two holes in a can top; condensed milk had long come in tin cans that were opened by stabbing the top at two points with the tip of an old-style can opener or even a small knife.)
Specialized tin cans were precursors of what was to replace the tin beverage can. Sardines were always a problem food, for they were to be served whole, yet they flaked and fell apart easily if poked with a fork or caught on the ragged edge of a can. To this day the German silversmith Wilkens sells special sardine forks with wide tines to give plenty of support to the sardine, and the points of the tines are connected by a silver bar so that they cannot pierce and flake the fish when it is served. Because sardines are so fragile, they came to be packed in tins that allowed the fish to be laid flat. And since a conventional opener would slash the contents of the can before exposing them, a special key was soldered to the bottom of the tin so that its top could be opened cleanly and completely by being rolled back upon the key, thus presenting the tightly packed fish as whole as they could be.
The idea behind the sardine can survives today in cans for coffee, peanuts, and tennis balls. These no longer come with keys but rather have pull rings riveted to their tops, which are scored along their periphery where they are designed to fissure and indented across their width to give them sufficient stiffness so as not to buckle and pull the sides of the can together in the process of opening. With the proper design of fracture lines and stiffening ridges, a top can be removed in a predetermined way without a separate opener and leave no rough edges to scratch the contents or the hand reaching for them.
Some consumers seem less squeamish than others about the use of cans. There is a television commercial in which a burly guy crushes a beer can against his forehead, and I get a headache every time I see it. Even though I know that today’s beer cans are pretty flimsy, and even though I know that squeezing the sides of the can just as it strikes the forehead makes it collapse harmlessly, my childhood memories of tin cans overrule any adult understanding I might have. I have yet to summon the courage to test my engineering predictions by crushing a can against my forehead.
A good deal of our visceral sense about how physical things behave was probably formed in our childhood, when we seemed to have more time and fewer inhibitions about looking closely at and experimenting with the stuff that we find all about us. My own sense of the strength of a beverage can was probably established by the time I was seven years old. While my buddies and I crushed cans under our feet to make tin overshoes, none of us ever joked about smashing a can against his forehead. If we had been asked what might happen if we did such a thing, we would probably have guessed something between a large gash and unconsciousness.
As the television commercial demonstrates, the evolution of beverage cans has outstripped previous generations’ understanding of them. What happened, as my friends and 1 grew into middle age, to turn the head-gashing instrument of the 1950s into the collapsible cream puff of the 1990s? Like all technological change, the story of the beverage can involves con- siderable interplay between pure engineering and social factors, not the least of which are economics and the environment.
In the late 1950s I was aware of few complaints about beverage cans. In fact, they were convenient and unremarkable things, although there may have been some talk about a growing litter problem. Other than their taller shape, beer cans were not unlike the familiar tins that contained food, except for being opened with a church key instead of a can opener. However, while consumers drank contentedly, the brewing industry was growing concerned about the steadily rising cost of tinplate—the tincoated steel out of which the cans were made. Kaiser Aluminum initiated a research and development effort that produced a lightweight and economical aluminum can in 1958. At around the same time, the Adolph Coors Company began its own research and development program, and in early 1959 Coors beer began to be sold in seven-ounce returnable aluminum cans the brewing company made itself.
The new cans were revolutionary not only in their raw material but also in how they were made. Whereas the relatively heavy old tin cans comprised three pieces, an aluminum can begins with a disk of metal that is first pushed into the shape of a cup like a tuna can and then stretched to make the taller sides. After the can is filled, a separate top is crimped on. Various improvements have been incorporated over the last three decades, especially in reducing the amount of metal involved, but the basic procedure remains the same. In the early years one pound of aluminum made fewer than twenty cans; today it provides thirty. The thickness of the can wall is less than five-thousandths of an inch—about the thickness of a magazine cover.
The walls of the can can be so thin because its contents are under pressure. Just as a flabby balloon stiffens as it is blown up, so the carbonation in a beverage can stiffens it. However, a flat can bottom would also round out like a balloon and make the can rock on the store shelf or the kitchen table, so the bottom of an aluminum can must be dished inward. By putting a convex face against the pressure, it acts like an arch dam in resisting the pressure of the fluid behind it. The can top, on the other hand, cannot be so dished and thus must be thicker than the rest of the container. To save metal in that thicker top, aluminum cans have come to have a characteristic stepped neck that requires a smaller-diameter top. Reducing the diameter as little as a quarter of an inch can save 20 percent of the metal required to make it.
While the first aluminum cans were noticeably easier to open than steel ones, a separate opener was still required. This was an inconvenience, especially when there was plenty of beer but no church key at the family picnic. It was in such a situation that Ermal Fraze of Dayton, Ohio, found himself in 1959, when he resorted to using a car bumper to open a can. The operation evidently yielded more foam than refreshment, and Fraze is reported to have said that there must be a better way. On a subsequent night, unable to sleep after drinking too much coffee, he went to his basement workshop to tinker with the idea of attaching an opening lever to a can. He was hoping the activity would make him drowsy, but instead “I was up all night and it came to me—just like that. It was all there. I knew how to do it so it would be commercially feasible.” Fraze could make such a judgment because he was the owner of the Dayton Reliable Tool and Manufacturing Company, and he had considerable experience with metal forming and scoring, the mastery of which would be essential to developing the pop-top can, for which he obtained the first patent in 1963. “I personally did not invent the easy-open can end,” he later asserted. “People have been working on that since 1800. What I did was develop a method of attaching a tab on the can top.”
Eventually a ring, which functioned as a lever, was riveted to a pre-scored tear strip. A pull at the ring broke the can’s seal Àand then lifted the attached strip of metal out of the can top along the scored outline. The hole that was left extended a good distance from the edge of the can to (or beyond) the center, and so as the can was tipped for pouring or drinking, air could enter the top of the hole and allow the easy, gurgle-free exit of the contents. The early pop-top or pop-tab worked reasonably well, not only eliminating the need for a church key but also replacing with one smooth motion the action of punching two separate triangular holes. Still, scoring a tear strip in a can top so that it will be easy enough to remove yet strong enough to hold against the internal pressure requires some rather tricky engineering. Some early pull tabs were blown off prematurely by the high pressure of the carbonation rushing out after a consumer’s initial cracking of the tear strip, so Fraze and other inventors came up with schemes to benignly direct the first whoosh of escaping gas away from the tab itself. Throughout the mid-1960s numerous patents were awarded for improvements in pull-tab devices. Then a new problem arose: environmental pollution.
By the mid-1970s those tabs that pulled completely off the can top were coming under increasing attack from environmentalists, and with good reason. 1 recall stopping at traffic lights in those days and trying to count up all the pull tabs (by then looking like little curledup tongues on key rings) among the cigarette butts beside the road. I could never finish counting before the light changed. Picnic sites and beaches were disastrously prone to the sharp litter, which was especially difficult to clean up because the small tabs passed easily through the tines of rakes. Animals, fish, and children were swallowing the tabs, and bathers were cutting their feet on them. Some conscientious people would drop the tab into the can after opening it; and some of them required operations when they swallowed the tab with their drink. In short, there was growing concern over the failure of the pull tab to function as well as desired in that regard, and this led to another rash of patent applications for easy-open cans without removable tabs.
Several clever schemes emerged to solve the loose-tab problem, and Coors was again in the forefront. It developed a two-step opening procedure, in which first a protruding metal button was pressed to break the pressure seal and then a second, larger button was pressed in to provide a drinking hole. Two-step opening procedures did not prove popular, however, and their shortcomings, which included the relatively forceful push required and the hazard of jabbing a button through the sharp edges of a hole, were not lost on inventors. They happily included in their patent applications, as a description of the prior art, the failings of existing solutions to provide an “easy-open ecology end” for the beverage can. A bewildering number of patents was being issued by the mid-1970s, but many of these were merely variations on the familiar pop-tab to prevent it from being pulled off all the way.
In 1975 a patent was issued to Omar Brown, of Kettering, Ohio—but the rights were assigned to his boss Ermal Fraze, the inventor whose name seems to be synonymous with easy-open can patents —for a “can end with inseparable tear strip.” In a section giving some background to the invention, Brown noted an especially vexing problem associated with simply folding the tear strip over the top of the can: “Since most people drink the contents directly from the can, it is quite probable that the user’s nose will contact a tear strip which is not fully removed from the can. If the edge of the strip is sharp, it is possible that he may cut his nose on it. On the other hand, if a sharp edge is formed around the pour spout, he may cut his lips on it.”
Brown’s solution included recessing the pour spout, thus keeping the lips from its sharp edges, and having the opened tear strip lie flat against the can top and away from the drinker’s nose. Another Ohio inventor, Francis Silver (who also assigned his patent to Ermal Fraze), protected the drinker by forming the tear strip so that it would fold away from the opening. No solution proved wholly satisfactory; each had its own apparent failings, not the least of which was leaving too much sharp and sticky metal bunched up on top of the open can. The version of the inseparable tear strip used on almost all beverage cans today appeared around 1980 as a variation on the Coors push button, but operated on the lever principle through an attached tab. Since the tear-strip panel is pushed down beneath but remains attached to the can top, the design reduces both the litter problem and the danger of swallowing a tab or cutting one’s nose.
When the pull tab removed the need for an opener, the aluminum can developed for beer was adopted for soft drinks as well. In 1965 Royal Crown cola became the first to use lightweight cans; Coke and Pepsi followed in 1967. Without bottom or side seams, the new cans could be decorated in much more elaborate ways than the old tin cans, and so aluminum was enthusiastically enlisted in the cola wars. Other advantages of the lightweight cans included lower transportation costs, compactness, stackability, and the reduced bulk of empties.
The one-time use of cans began to argue against them, however. By the early 1970s beer and beverage cans were being emptied at the rate of thirty billion a year in America, and ban-the-can bills were under consideration by a majority of state legislatures. Tin-plated steel cans, which were still in the majority, would at least rust in landfills; aluminum would not. As Coors recognized from the beginning, recycling aluminum was not only environmentally responsible, it was also essential to the long-term popular acceptance of the new technology.
By 1975 about one in four aluminum cans was being recovered; by 1990 the rate exceeded 60 percent. It is the joint goal of the Aluminum Association, the Can Manufacturers Institute, and the Institute of Scrap Recycling Industries to achieve a reclamation rate of 75 percent by 1995. This not only makes sense environmentally, it is also good business. Recycled cans are essential to supplement the general aluminum supply, and the collection infrastructure is now so efficient that the metal in a used can may appear in a new one in as soon as six weeks.
By 1990 aluminum accounted for about 97 percent of all beer and soda cans made in America. At the same time, some 95 percent of all food cans remained tin-plated steel, because an economical aluminum container is typically not strong enough to keep its shape without the pressure of carbonation. We may begin to see more aluminum food cans in the future, however, as the industry develops strengthening techniques that include injecting liquid nitrogen into cans to provide pressure and corrugating the can walls.
To counter its failings, the steel-can industry is engaging in research and development of its own. The economics have been working against steel beverage cans in part because they have had to be fitted with aluminum tops to be easy-opening. Steel has the recycling advantage of being magnetically separable, but the presence of the aluminum complicates the recovery of the metals. A new ringpull can end made of tinplated steel may remove that objection, if it can be made easy to open and smooth-edged. The Steel Can Recycling Institute was formed in 1988 in the hope of diminishing aluminum’s advantage in terms of recycling. Some steel-can manufacturers are redirecting their research and development efforts toward plastic cans that can be placed directly in a microwave oven.
Although perhaps a trillion aluminum cans have been produced and used over recent decades, and although hundreds, if not thousands, of patents have been issued for improvements to them, the form has hardly been perfected. In the newest pop-tops the opening is generally oval-shaped and does not extend completely to the edge of the can. Pouring and drinking are a bit tricky. Tipping a full can too far prevents air from entering readily, and a nearly empty can must be tipped almost upside down to get at the last of the beverage. We tend to adapt to the available technology, however, and we seem to have come to tip our cans in the same way we came to tip our bottles, at just the right angle for the level of the contents. However, unlike bottles, whose narrow necks gave us plenty of room to maneuver, the tabs attached to pop-top cans do come up to meet our noses if we are not careful. They no longer pose a threat of cutting us, but they do restrict how far the container can be tilted, so we must throw back our necks farther.
Still another functional imperfection of the familiar beverage can is its inability to be reclosed. Cans of coffee, nuts, and tennis balls typically come with plastic lids that can be used to re-cover, if not reseal, the opened container, but beverage cans generally do not. While those who sell beer and soft drinks, or even those who consume them, might not see this as a particular disadvantage, the failing has attracted not a few inventors. One is Robert Wells of Steamboat Village, Colorado, who, in 1982, was issued a U.S. patent for a reclosable self-opening can end. Wells’s patent, like most associated with can-opening and -closing devices, is a rather long one. It includes forty-seven drawings and fifteen claims showing variations on his ideas for a part that can be slid or rotated into position to plug the can’s opening. Many of his proposed schemes seem much too complicated for a twelve-ounce beverage container, and it appears unlikely that any reclosing device will become standard on the pop-top can. Most of us might prefer to drink our drinks more quickly or discard their flat remains rather than deal with a touchy device to reseal them.
Another drawback of pop-top cans is the close-fitting pull ring or tab. People with arthritic fingers or long nails have trouble prying up the pivoting device to break the seal. Unsurprisingly, two California inventors, Robert DeMars and Spencer Mackay, have recognized this shortcoming. In 1990 they received a patent for a beverage container opening and resealing device. It owes its novelty principally to a little hill, or “camming protuberance,” that juts up from the can top. To open the can, you rotate the tab onto this hill, thus lifting one end of it. This both pushes the other end of the tab into the can top and lifts the near end so that even the stiftest and stubbiest of fingers can get hold of it to complete the opening. Closing the opened can is effected by peeling a protective covering off the now-exposed bottom of the tab to reveal an adhesived underside that can be folded down, rotated into place, and wedged over the opening with the help of the hill. The procedure takes five figures to explain in the patent and thus may appear to be as complicated as other resealing schemes. But even without the resealing aspect, a beverage can with something like a “camming protuberance” might be a sight for sore hands.
Independent inventors will no doubt continue to come up with ingenious schemes to overcome the various objections to opening and drinking from cans as they are now made, while the companies that make and fill the cans will want, above all, to keep them as effective and as affordable as possible. Of late, technical questions relating to the practicality of steel versus aluminum have tended to dominate can design and use, and considerations of ultimate convenience for the consumer have been largely crowded out of the corporate, if not the inventor’s, mind.
Since consumers tend to adapt to the pop-top—as to all technology—that is available, there is often no immediate business advantage in exploring improvements. However, if an improvement gives one brand of beverage an advertising or marketing advantage over its competitors, it stands a chance, although there can also be a competitive risk in introducing an innovation that makes the product unfamiliar. Ultimately, whenever environmental or consumer concerns about the product are perceived in terms of real failure, as they were with removable pop-tops, then manufacturers know they have a clear incentive for change. A manufacturer’s concerns may sometimes appear arcane or selfish to the consumer, but they are in fact driven by failure, functional or financial, no less than is any other aspect of the process of design and redesign through which even our most familiar artifacts evolve.
