Shrink-Wrap Plastic History: A Little Heat Goes a Long Way

There is a lot more in the article than this:
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!