The double-hexagon-shaped molecule is also a notorious endocrine-disruptor, which means that it interferes with hormonal biology. Unfortunately, BPA does more than make plastic plastic. It, alone among foods, requires three layers of lacquer, and even with that much protection, still boasts a shorter shelf-life than its peers. The top of the corrosive list, though, belongs to rhubarb. Those for meats must contain a lubricious wax, called a meat release agent, so that the meat slides right out.Įxtra challenging are fruits and vegetables including beets, currants, and plums, which contain the red pigment anthocyanin, because they’re some of the most corrosive. Chocolate, especially sensitive to adulteration, requires its own coating.
For beer, engineers might use a coating that contains cyclodextrin, a donut-shaped carbohydrate that traps bad-tasting molecules. There’s one coating for tomatoes, one for beans, one for potatoes, and another for corn, peas, fish, and shrimp.
Coatings for tomatoes must be stain resistant, those for fish must resist sulfur, and those for fruits and pickles must resist acids. They’re also very specific: for nearly every variety of food or beverage, there’s a coating that’s been devised just for it. The formulas for coatings are proprietary, but we know the epoxies must be affordable, sprayable, curable, strong, flexible, and sticky. (Ball has developed a carefully-guarded formula quantifying all of this corrosion badness, but it was not displayed on any graph at Can School.) Red #40 is pretty bad, and high chlorides are really bad, and together, they’re really, really bad. Citric acid and phosphoric acid are equally bad. Thus, Diet Coke underperforms regular Coke on at least two counts.
It absorbs carbon dioxide, decreasing the pressure within a can, and it also inhibits other corrosion reactions, because sugar tends to deposit onto pores in the coating.
SODA CANS HOW TO
Empirically, Ball has figured out how to determine the corrosivity of potential products. Otherwise, cans explode, and legal costs climb. (Roughly one in seven new energy drinks are too corrosive to put in cans.) Ball is not in the business of sending cans out into the world to be slaughtered by overaggressive liquids. Also, some beverages are so corrosive that no amount of coating will protect their cans. The epoxy coating, after all, costs about a half penny per can and Ball doesn’t want to waste it. (Without that shield, a can of Coke would corrode in three days.) At Can School, I got a hint of what goes into that coating.īefore coating the insides of their cans, Ball needs to know how corrosive the beverage within will be. Rust, it turns out, is a can’s number one enemy-and a can’s only defense is an invisible epoxy shield, just microns thick. But mostly, cans yearn to corrode (thereby leaking onto other cans, and causing more corrosion). Once filled, it wants to interact with the product inside and change its taste. Throughout the process, the aluminum behaves begrudgingly. Yet even with that much practice, making perfect 12-ounce cans remains a battle. The people of the world go through 180 billion aluminum beverage cans a year enough to build dozens of towers to the moon. If you drink beer, or soda, or juice, or sports drinks, or if you have ever preserved fruits or vegetables in glass jars, the name Ball probably sounds familiar. One guy handed me a business card that said “Can Whisperer.” Another wore a shirt that said “Can Solo.” It was a scene of intense devotion, and as such, it was only fitting that the first thing I learned there was that manufacturing aluminum cans is so challenging, and requires such a vast amount of study, design, and precise machining, that many consider cans the most engineered products in the world. There, in a conference room just north of Denver, engineers chatted about “improved pour rates” and “recloseability” and the “opening performance” of cans. It is, in fact, a glorious thing.Ī few years ago, I finagled my way into Can School, a small industry-only event hosted annually by the Ball Corporation, the world’s largest canmaker. But that seemingly unremarkable object is actually a marvel of modern manufacturing. When was the last time you paused between sips of your favorite soda and wondered about that can in your hand? If you’re like most people, the answer is likely never.