"Terminology: Polystyrene, Styrene, Foam, Styrofoam, etc." Topic

I hear those terms thrown about all the time in discussions about terrain. And I really don't think that most of us are all on the same page. Not surprising, since not all of these materials are available everywhere.

However, and someone may have already this up, there's an Antenociti article that seems to clear up a lot of those differences:

link

Those definitions seem to go well with some of the other definitions I've found for the term "polystyrene":

link

So, based on those explanation, this is how I understand the different types of polystyrene out there:

1) The dense EXTRUDED polystyrene type used within paper-covered foam boards or in thick insulation boards (blue or pink boards);

2) The beaded EXPANDED polystyrene type (used to make white cheap and brittle beer coolers); and

3) The THIN HARD MOLDED polystyrene type (like with the vacuum-formed Amera buildings, or the Evergreen or Plastruc "styrene" sheets).

Did I get it right?

Thanks,

Dan
TMP link

Styrene and Polystyrene are pretty much the same thing. A hard plastic that can be extruded into any number of shapes.

"Foam" refers to any number of beaded or extruded foam products.

"White Stuff" is generally a beaded foam. This product is generally the cheapest, possesses the least amount of strength and can be hard to work with.

"Blue Stuff" is Styrofoam -- which is a trade name IIRC. Blue stuff is readily available where I live and is pretty strong and pretty easy to work with but does cost quite a bit more than white stuff.

"Pink Stuff" is another extruded foam product -- denser than Blue stuff and stronger too. It too is pretty easy to work with but is not commonly available in the Pacific NW -- probably because it costs more and does about the same thing.

Well that's the extent of my knowledge on this subject.

mjc

yes that pretty much sums it up.

Did I get it right?

Yup ;-)

D

antenocitisworkshop.com
governanceoftechnology.com

"Pink Stuff" is another extruded foam product -- denser than Blue stuff and stronger too.

Jed says:

"The colour of the foam used to indicate the brand name and the density, but that is no longer always the case as you can get (blue) "Styrofoam" and blue "Floormate", different brands, same type of material.
And each of those can be different density (strength) than each other and within the same range.

So it's dangerous to assume that "Pink" will always be stronger than "Blue", as there are plenty of blues that are stronger than pinks, greens or whites. It isn't 'wrong' mind you, as there are Pinks that are stronger than Styrofoam, it just isnt always true! ;-)

What you need to look at is the actual density, as the denser the material the stronger it is.

For wargaming purposes anything of a density over & around 32kg/m3 is good.

Lower density will mean it is easily indented by elbows resting on it etc, higher density will mean it is stronger, more resistant to all forms of damage, but heavier and harder to work with."

D

antenocitisworkshop.com
governanceoftechnology.com

So what is different in the sheet styrene that allows you to use solvent-based spary paints on it, versus the metling effect you get when you try to use it on Sytrofoam, pink stuff, etc.?

From the chemist's POV:

Styrene, Tech: the monomer that react to form polystyrene.
Polystyrene, Tech: The polymer chain of the monomer Styrene.
Foam, Tech: Any gas suspended in a solid.
Styrofoam, Tech: A brand name for one form of extruded polystyrene foam.

Polystyrene
plastics.inwiki.org/Polystyrene
is the basic plastic from which "Hard" plastic models and Styrofoam is made. It is really a blend of plastics, but the vast majority is Polystyrene. Also, plastic card as sold by Evergreen or PLASTRUCT are also Polystyrene.

For terrain work:
There are basically two types of Polystyrene Foams
Expanded Polystyrene (EPS):
link
This is the white stuff made up of little balls of foam stuck all together. Also commonly called bead board. Used to make packing material for electronics, appliances etc. If broken or rubbed on too hard will break into many small balls.

And
Extruded polystyrene (XPS):
link
Also called homogeneous polystyrene foam. It is often colored to help with branding. Pink, Blue, Yellow, Brown, Grey, Purple, and pure white. I have seen all these colors. And the color alone tells you very little. Some vendors use different colors to keep different thickness of foam panels straight in the warehouse. If you break this or rub it hard you get dust.

Another consideration is density:
Density is a measure of how heavy something is for the same volume. Lead is denser then wood. In polystyrene foam terms, the denser the foam the stronger, less flexible, and harder to crush it will be. You may hear of "NATO" density which is one of the higher density standards for both EPS and XPS.

One more thing, plasticizers:
You may note that the foam you get from craft store is much more brittle then the foam used in construction. This is because of a slight difference in the formulation of the plastic. Also you will find some packing materials are especially soft and squishy. This is due to the different amount of plasticizers included in the mix.

One finial thing: Plastic foams that are not polystyrene.
You will find other plastic foams out there. Polypropylene and polyethylene are now common for packing materials. The feel sort of waxy and are hell to cut and paint well. Polyurethane is also use as construction panels. It is a tan to brown could and is most often has foil on both sides to protect it from UV light. It can be used, but do not heat it as it will burn and not melt. It can be carved very well and is sold form this use as "Balsa-Foam"
link

It is great but you need to keep in mind it is not polystyrene and use the right techniques for each.

DyeHard:

Don't put too much emphasis on the color though – learn to recognize the material itself. Most plastics have a whitish, milky color in their raw form…the color is a branding thing.

For sheet foam, I like Certifoam – it is the same general material as the pink and the blue…but it is yellow. However, as Dyehard mentions – the formula is a bit different due to the plasticizers. The Certifoam is less squishy without being brittle.

Recently I have played around with a black extruded polystyrene foam that has fiber reinforcement mixed in. I forget the brand name off the top of my head.

Toss into the mix phenolic foams – most floral foams are phenolic foams.

Polyisocyanurate foam – generally yellowish, usually foil faced on one side. Like Polyurethane foams, you can cut and carve it…but avoid hotwire cutters.

And don't forget the thin foam products in their various forms. Foam core (paper faced bead board), Depron (really thin extruded polystyrene), Gator Board (extruded polystyrene with a fiber facing…harder than normal foam core), Cellfoam 88 (sort of like Depron)…

For the "styrene" – the general term used is High Impact Polystyrene when referring to the plastic stuff. You can use that term to track down sheets which cost a tiny fraction of what a similar thickness would cost from Plastruct or Evergreen.

In the same vein as the HIPS you will find butyrates, acrylics, ABS, acetates and PVCs. Those are handy since you can solvent weld them to each other without too much difficulty (Plastruct sells a pretty good universal adhesive for working with most of them).

Other less useful plastics can also come up from time to time (polyester, polypropylene, polyethylene and nylons). For me, personally – I prefer to avoid these plastics as they are more difficult to glue.

Lots and lots and lots more variations still…some are useful, some not so much.

Another useful bit of info…most polymer clays (FIMO, Sculpey…) are PVC plastics. You can actually solvent weld those to other PVC (like pipes and sheet stock) as well as to compatible plastics using the correct solvents.

Ok, so what do you guys think this means . . .

"Made from clear OPS plastic and available in all the popular shapes and sizes"
link

Thanks,

Dan
TMP link

This is "oriented polystyrene" (OPS)
rdi-inc.com/orientdedPS.html

From the model making perspective it is the same as polystyrene.

The oriented term is just to reduce glare and distortion when you look through it. Developed for food packaging.

DyeHard

Very cool!

Thanks,

Dan

If anyone wants smaller sheets of expanded PS, here's Cellfoam 88:

link
link
link

More:
TMP link

Dan