Today in Tedium: In the age of instant takeout, there may be no greater scourge than polystyrene, a necessary evil of many a food delivery. New York City, famously, tried to ban the foamy substance before a judge struck down the ban . And lots of other cities have tried to follow suit—most aggressively San Francisco , and most recently Bangor, Maine . Heck, the entire state of Maryland is considering a big ban. We know that polystyrene is bad for the environment, that it’s frequently mistaken for Styrofoam, and that it’s kind of a crappy way of shipping food to people. Where does it come from and why does it persist? Today’s Tedium ponders. — Ernie @ Tedium

The year that Dow Chemical engineer Ray McIntire discovered the process of making Styrofoam , which he did by accident. Mcintyre was hoping to create a more rubber-like substance when he combined polystyrene and isobutylene, but the discovery proved incredibly important anyway, immediately getting used during World War II. He didn’t discover polystyrene, which came about in the 1800s ( also an accident ), and Swedish inventor Carl Georg Munters beat McIntire to the punch on the discovery front, but Dow turned it into a household name.

This material is not Styrofoam. Don't let anyone tell you differently. (Björn Láczay/Flickr)

What’s the difference between styrofoam and polystyrene, anyway?

It really sticks in the craw of Dow Chemical that we call foam food containers “Styrofoam,” despite the fact that Dow has trademarked that name for more than 60 years.

In a 2013 Washington Post article, Dow’s business director for building solutions in the Americas, Tim Lacey, sounded like he was at the end of his foam-laced rope.

“We’re doing everything we can to make sure that it’s used properly,” Lacey explained. “We don’t really know why everyone wants to land on the name Styrofoam, and why it serves as something people want to misuse.”

That’s because, when you’re using a cup, plate, or other material, you’re using a material that’s actually called expanded polystyrene. And as Dow Chemical and Owens Corning, the two primary manufacturers of extruded polystyrene, will tell you, it’s not a small or modest difference.

In a lot of ways, the process used to make a cup, versus building insulation (the primary modern use of extruded polystyrene) is the difference between a million pieces of foam and a solid brick. The cup you grabbed from the Shell station? That’s built using a molding process, in which relatively malleable balls of polymer are pressed into a specific shape after those polymers have been filled with gas. (Larger balls might be used for coffee cups, smaller ones for foam trays.)

As a result, there’s a lot of air in there, which makes the cup lightweight and flexible, while still gaining the insulation advantages that come with foam.

The problem is, there are cases where you can live with a little more weight and a little less flexibility, because you want the resulting material to be a lot stronger. That’s where the extrusion process comes in.

A good way to explain this is to go back to the way cheese curls are made, because those also use an extrusion process, except with flakes of corn instead of polymers of styrene oil. But there are some differences, however: You want air in your cheesy poofs, so you pop them straight out after they’re ready to puff up.

But let’s say you want to extrude something that was more crisp, closer to a tortilla chip than a Cheeto. You’d have to figure out a way to more tightly control how the extrusion process manages air to achieve more concentrated results. With Styrofoam, the extrusion process is managed in this way, designed to minimize the amount of air that gets through the material, so as to make the material very tough.

The result of this is that the material you get with extruders is designed for longer-term uses, like in houses. This clip from Owens Corning does a good job explaining why extrusion is desirable in the case of building materials: Simply, it’s tougher, because there’s less air than you’d find in expanded polystyrene. Because there’s less air, it’s very difficult for water to seep in through such material.

Building materials are meant to hold up for decades or longer. Single serving food? It only has to hold up as long as your delivery driver takes to get the Ethiopian food delivered to your door without the driver getting tsebhi birsen all over their vehicle.

The problem is, of course, it lasts a lot longer than that.