Tedium - Wrapped Up 🦃

Today in Tedium: You know something you probably don’t think about too much when you walk into a store, but it’s honestly everywhere you look, most likely? At one level, it’s plastic. But let’s narrow our gaze to a more specific type of plastic—the shrink-wrap that covers many basic goods that we purchase on a daily basis. It’s a sign that the thing you’re looking at hasn’t been tampered with, is original, and is otherwise good to use. It’s a common, if poorly understood, object in our lives and a key element of ASMR videos that you’ve probably spent an afternoon watching when you were bored. So how’d we get it? Today’s Tedium wraps its head around shrink-wrap. — Ernie @ Tedium

Today’s GIF features an image of someone shrink-wrapping their sneaker, which is something sneakerheads apparently do.

(Emily Bernal/Unsplash)

Understanding the power of shrink-wrap and other forms of sealed plastic

About a month ago, I came across an interesting video done by the folks at Lifehacker. Here’s the basic gist: A pair of video creators saw a TikTok clip in which someone took a plastic bag, of the kind you might store snacks in, and cut it in half with a red-hot knife, and that knife was hot enough that it split the plastic bag in two—and both ends remained sealed.

They tried the trick themselves, and they found out that it not only worked, but it worked really well.

In many ways, shrink-wrap borrows from a similar, if not the same, concept. At high temperatures, plastic tends to firm up and tighten up thanks to the heat, rejiggering the molecules into a new shape. It will reshape itself around the material, creating a tight fit around what might have previously been a loose one.

Ziploc bags and their generic counterparts tend to be made up of a variant of plastic that’s also used in many forms of shrink-wrap, polyethylene—and heat (ofter in the form of a heat sealer) is often a key tool used in the creation of those products. So it makes sense that the material created a similar effect with plastic baggies.

Plastic and heat have something of a close relationship. Plastic wouldn’t look like it does today without a little heat to help mold it and a little chill to harden it. And shrink-wrap is a great example of how plastic can reach its full potential when heated.

Of course, shrink-wrap, no matter your views on plastic, is a fascinating concept, an example of innovations in the fields of chemistry, manufacturing, engineering, and physics coming together to help solve one of packaging’s great challenges—how can packages be properly and securely sealed before reaching consumers? The story is more complicated and interesting than it sounds.

It starts with birds wrapped in bags, and it has more in common with the Large Hadron Collider than you might think.

The Butterball turkey, and others like it, was an important test case for shrink-wrap. (pinkmoose/Flickr)

Birds wrapped in bags: How frozen turkeys helped get us shrink-wrap

So to start with, let’s talk about the birds wrapped in bags. In the late 1930s and early 1940s, a technique called cry-o-vac emerged as a way to vacuum seal turkeys and chickens inside of bags. The approach worked like this: A plastic film was wrapped around a whole bird, and then vacuum sealed. The packaged poultry was frozen and then put through a number of heat and cooling cycles, which caused the wrapping to firm up around the packaging, making it possible for the birds to be preserved for longer periods, while keeping the flavoring strong.

While not exactly shrink-wrapping it as we know it, this technique formed the basis of a startup firm, called Cryovac, Inc., in 1946. (The term was first trademarked in 1939, however, and newspaper ads and mentions date its existence well before the formation of the actual company.) A division of the Dewey & Almy Chemical Company, the firm emerged as something of an innovator in food packaging, though it has generally remained a subsidiary of a larger company throughout its history, with the company offered the room to come up with new techniques.

The process of heating and chilling the plastic in this way was a big innovation, but there were more directions to take it. One of those directions involved coming up with a method to destabilize the plastic molecules so that they were basically primed for wrapping around an object. And much like magnets next to an old CRT, it involved messing around with an electron gun.

This gets us to the comparison to the Large Hadron Collider. See, at its root, the CERN device is a particle collider, the world’s largest, in fact. A particle collider is just one type of particle accelerator, but there are numerous others that are nowhere near as large.

And some of those particle accelerators are used to create shrink-wrap. In the 1950s, it was discovered that treating plastic with electromagnetic waves, also known as ionizing radiation, had the effect of shaking up the molecules, so that with a little heat, the plastic would become malleable, rather than something that would be likely to melt.

This process was first applied to bags for turkeys, but then to everything else.

Heat shrink, which I mentioned above, uses basically the same technique, and offers a great example of what shrink-wrap and similar materials are capable of. In the clip above, a person uses a lighter to heat up heat shrink to fuse it to the cable, effectively shrink-wrapping a cable in what would otherwise be a sensitive spot.

In fact, it should be noted that Cryovac’s Bill Baird, who helped develop the shrink-wrap technology for the firm, actually met with Raychem founder Paul Cook, the inventor of heat shrink, to see if there were any lessons that could be gained. Turned out, there was. Not long after this meeting, which could potentially be described as the plastics version of Steve Jobs visiting Xerox PARC, Baird applied the concepts of irradiated polyethylene to turkey bags. And it turned out, it worked!

Just shooting plastic with an electron gun to make it shrink better on my turkeys, nbd. (Google Patents)

In a 1962 patent granted to W.R. Grace and Co., the firm that purchased Cryovac in 1954, the authors (including Baird) made it clear the challenges they were having in getting polyethylene to shrink using the traditional freeze-heat-chill method:

Polyethylene is finding increasing usage as a packaging material. However, due to the fact that regular polyethylene does not have high shrink energy, it cannot be utilized satisfactorily in a process such as the Cryovac process wherein a piece of meat, for example, is placed in a bag formed of heat-shrinkable plastic film, the bag evacuated, sealed and heated by contact with hot air or contact with hot water or other fluid to shrink the bag about the meat to eliminate dead spaces between the meat and the bag to increase preserving qualities and also eliminate wrinkles of the film and improve overall appearance of the package.

But by putting it in a machine with a particle accelerator slamming the polyethylene with electrons, the material quality of the plastic had changed significantly, making the plastic far more malleable.

“While irradiated polyethylene, e.g., lrrathene, is normally considered harder to seal than regular polyethylene, the polyethylene of the present invention seals more easily than conventional polyethylene,” the patent continues. “The products of the present invent on have improved hot cohesive seal strength which makes them particularly useful in applications requiring high speed heat sealing.”

In other words, they just found a way to make turkey packaging awesome. It made the plastic not only more malleable but also meant it could be thinner than heat-shrink plastic could be previously.

“It was really a major packaging innovation. Without, the industry would not have been able to grow at the rate it did,” explained Dan Blackshear, a longtime turkey-industry executive, in an Associated Press report.

And it wouldn’t be long before the destabilizing influence of electrons on polyethylene was applied to pretty much any consumer good you can think of.