# extruded/expanded polystyrene, American names for **URL:** \ **Category:** Factual Questions\ **Created:** [March 17, 2019, 5:41pm UTC](https://boards.straightdope.com/t/extruded-expanded-polystyrene-american-names-for/831269 "2019-03-17T17:41:53Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Cayuga](https://avatars.discourse-cdn.com/v4/letter/c/3e96dc/32.png) [@Cayuga](https://boards.straightdope.com/u/Cayuga)\ **Post date:** [March 17, 2019, 5:41pm UTC](https://boards.straightdope.com/t/extruded-expanded-polystyrene-american-names-for/831269/1 "2019-03-17T17:41:53Z")
[Mods: This question originated from an artistic/crafty situation, but it seems to me that it transcends Café Society placement. Correct me if I’m wrong.] I’m watching a lot of You Tube videos of people making dioramas and model railroad scenery. Most of them are British, probably English, and many of the rest are Australian. They all use blocks of foam that they call “extruded polystyrene” and "expanded polystyrene. I _think_ that expanded polystyrene is what we in the U.S. usually refer to with the brand name Styrofoam, but I don’t know if that’s correct, and I have no idea what extruded polystyrene might be. A little help? ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [March 17, 2019, 6:35pm UTC](https://boards.straightdope.com/t/extruded-expanded-polystyrene-american-names-for/831269/2 "2019-03-17T18:35:12Z")
You’re right about expanded often being called Styrofoam, and extruded is often called that too, or “blue board”, or XPS. ---
**Author:** ![Littleman](https://avatars.discourse-cdn.com/v4/letter/l/ccd318/32.png) [@Littleman](https://boards.straightdope.com/u/Littleman)\ **Post date:** [March 17, 2019, 6:42pm UTC](https://boards.straightdope.com/t/extruded-expanded-polystyrene-american-names-for/831269/3 "2019-03-17T18:42:58Z")
You’re correct. I will note though that the carvable and sandable nature of different types makes a big difference for your intended purpose. I could try and guide you to some sources that work better than others . (Some forms flex or fall apart in balls when worked worse than others) I’ve carved quite a bit of mold plugs for theme parks or vehicle parts from it. Though since it’s kind of a non-standard application it can be dodgy and experimental getting really great sources. A good start for most people is pink rigid insulation panels if you’re not working on the scale I was. Thicker pieces can be joined up using can foam insulation. Kwik foam is a favorite for this, it’s cheap and rigid. For laminating panels you can pull apart and put back together multiple times, which keeps it from expanding. ---
**Author:** ![Johanna](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johanna/32/8318_2.png) [@Johanna](https://boards.straightdope.com/u/Johanna)\ **Post date:** [March 17, 2019, 6:45pm UTC](https://boards.straightdope.com/t/extruded-expanded-polystyrene-american-names-for/831269/4 "2019-03-17T18:45:30Z")
[X-banded Poly Styrene](https://youtu.be/aZWRa4qlwZo?t=4) ---
**Author:** ![Littleman](https://avatars.discourse-cdn.com/v4/letter/l/ccd318/32.png) [@Littleman](https://boards.straightdope.com/u/Littleman)\ **Post date:** [March 17, 2019, 6:46pm UTC](https://boards.straightdope.com/t/extruded-expanded-polystyrene-american-names-for/831269/5 "2019-03-17T18:46:59Z")
> [@MrDibble](#): > > You’re right about expanded often being called Styrofoam, and extruded is often called that too, or “blue board”, or XPS. Yes, EPS also ---
**Author:** ![Melbourne](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@Melbourne](https://boards.straightdope.com/u/Melbourne)\ **Post date:** [March 17, 2019, 10:36pm UTC](https://boards.straightdope.com/t/extruded-expanded-polystyrene-american-names-for/831269/6 "2019-03-17T22:36:23Z")
Expanded polystyrene is a foam, eg Styrofoam. It comes loose as balls (for bean bags) or packing peanuts. And it comes as blocks where, if you look carefully, it seems to be made of balls stuck together. Extruded polystyrene is hollow sheeting, made up of tubes of thin plastic extruded side-by-side, used to make boxes, signboards etc. In structure, kind of similar to corrugated cardboard. I’m told that the sheets are sometimes built up into blocks, but I’ve never seen that. ---
**Author:** ![Cayuga](https://avatars.discourse-cdn.com/v4/letter/c/3e96dc/32.png) [@Cayuga](https://boards.straightdope.com/u/Cayuga)\ **Post date:** [March 18, 2019, 9:35am UTC](https://boards.straightdope.com/t/extruded-expanded-polystyrene-american-names-for/831269/7 "2019-03-18T09:35:48Z")
Cool. Thank you, everyone. Ignorance fought.