Trains.com

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Which type of foam is which?

2574 views
12 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    February 2021
  • 1,110 posts
Which type of foam is which?
Posted by crossthedog on Friday, August 11, 2023 6:55 PM

I followed the link in that Plastruct thread and started wandering, found a section on polystyren and urethane foams and styrene foam board. I think that one of these is what I want, but there are no photographs to show me which term refers to what kind of foam, just line drawings.

I've seen many examples over the years of foam used for scenery in layout pics here, but I can never keep straight what is what. I hear terms like extruded foam, but when you go online to look for that, you find both EPS and XPS. I think one of those might be the kind of "styrofoam" that keeps your new TV from sloshing around when you bring it home -- the white stuff with the beads. I don't want that. I've seen pink stuff that looks sculptable, and a rich blue colored foam, both about 2" thick. One of these may be carvable with hot wire tools, the other not. Can someone post some photos and tell me exactly what kind of foam we're looking at and what the characteristics are of each?

I could go up to Home Depot I guess; even though I don't want or need (nor can I afford) 4x8 sheets, I could at least see and feel the items they have before buying smaller sizes from Plastruct. 

For a small area around the Perkins, I bought a couple small bricks of craft foam. You can shape it by rubbing your thumb on it, it's so crumbly. It's like smoke. It falls apart at the touch and its fine particulates cling statically to everything. It was perfect for the spot but I don't want to use more of it.

Any help appreciated.

Thanks,

-Matt

 

Returning to model railroading after 40 years and taking unconscionable liberties with the SP&S, Northern Pacific and Great Northern roads in the '40s and '50s.

  • Member since
    December 2004
  • From: Bedford, MA, USA
  • 21,483 posts
Posted by MisterBeasley on Friday, August 11, 2023 7:37 PM

What you want is extruded foam.  The pink stuff is from Dow, and the blue stuff is Owens Corning.  Otherwise, they're the same.  Don't quote me on chemical company names ,  I'm retired.

The green stuff, as well-informed tradesmen say, is called green board.  I think it's for bathrooms.  Unless that's drywall for bathrooms.

You don’t want the white stuff that crumbles.  That's packing material.

I use the pink stuff, 2 inches thick, from Home Depot.

It takes an iron man to play with a toy iron horse. 

  • Member since
    April 2023
  • 29 posts
Posted by Lost in A2 on Friday, August 11, 2023 8:36 PM

MisterBeasley

What you want is extruded foam.  The pink stuff is from Dow, and the blue stuff is Owens Corning.  Otherwise, they're the same.  Don't quote me on chemical company names ,  I'm retired.

You've reversed the colors: Owens Corning has used the pink panther logo for a very long time. 

  • Member since
    January 2017
  • From: Southern Florida Gulf Coast
  • 18,255 posts
Posted by SeeYou190 on Friday, August 11, 2023 8:42 PM

Matt, what you want is foam insulation board without any liner or covering.

We don't sell it down here in South Florida in 4 by 8 sheets, because it does not meet code with our common building materials and methods. We do sell it in 2 by 2 sheets 3/4" thick for hobbiests.

I buy it in Indiana when I am there on Vacation and smuggle it back home, along with other assorted contriband items (like Homasote) from Home Depot, Menards, and Lowes from out of state.

-Photograph by Kevin Parson

Big Smile  Pirate  Big Smile  Pirate  Big Smile  Pirate  Big Smile  Pirate  Big Smile  Pirate  Big Smile  Pirate  Big Smile

-Kevin

Living the dream.

  • Member since
    December 2004
  • From: Louisville
  • 588 posts
Posted by dbduck on Friday, August 11, 2023 10:22 PM

If you live in an area that allows the pink or blue extruded foam to be used in construction, sometimes you can go by the construction site and check with the contractor to see if they have any usable scrap pieces 

  • Member since
    February 2021
  • 1,110 posts
Posted by crossthedog on Saturday, August 12, 2023 12:50 AM

Gentlemen, my thanks for these responses.

@Beas, thanks for jumping in. I had a feeling that the pink Owens Corning stuff (thanks for the correction @Lost in A2) was what I was after, but it mostly comes in expensive giant sheets. I don't at all mind paying for things, but I don't need 32 square feet of the stuff, so I've been looking at online suppliers that might sell smaller pieces. The problem is that I am uncertain of the terminology.

@dbduck, this was exactly my thought. I wasn't sure where to start, but I figured some place that custom cuts the big sheets for people might have some sizeable but unsaleable scraps lying around. But I wanted to make sure I knew what i was after first.

@Kevin, I forgot you worked at Home Depot. So to clarify, in your picture the tan/brown/beige is foam insulation board and the pink layers are the Owens Corning extruded foam insulation? And that's XPS (X for extruded) not EPS? Is that the stuff you can cut with a hot wire tool?

-Matt

   

Returning to model railroading after 40 years and taking unconscionable liberties with the SP&S, Northern Pacific and Great Northern roads in the '40s and '50s.

  • Member since
    December 2004
  • From: Louisville
  • 588 posts
Posted by dbduck on Saturday, August 12, 2023 1:27 AM

I got more than enough blue foam about 2 years ago

Apparently somebody lost about five sheets of the 2 inch driving along the interstate. I happen to be driving by and saw all of the sheets on the side other side of the road.

On my way home. They were still there so I took my car home. Got my van and went back and got them.

  • Member since
    May 2008
  • From: Miles City, Montana
  • 2,289 posts
Posted by FRRYKid on Saturday, August 12, 2023 2:22 AM

crossthedog

For a small area around the Perkins, I bought a couple small bricks of craft foam. You can shape it by rubbing your thumb on it, it's so crumbly. It's like smoke. It falls apart at the touch and its fine particulates cling statically to everything. It was perfect for the spot but I don't want to use more of it.

Late to the party here but from what you're describing it almost sounds like you have the type of foam that florists and crafters use for mounting fake flowers. (I work in a place that sells the stuff so I'm familar with it.)

"The only stupid question is the unasked question."
Brain waves can power an electric train. RealFact #832 from Snapple.
  • Member since
    August 2003
  • From: Collinwood, Ohio, USA
  • 16,367 posts
Posted by gmpullman on Saturday, August 12, 2023 2:42 AM

FRRYKid
   —it almost sounds like you have the type of foam that florists and crafters use for mounting fake flowers.

 

AKA Oasis floral foam:

https://a.co/d/aQHhzQj

Not something you would ever use around a layout. It decomposes rather rapidly.

Regards, Ed

  • Member since
    January 2017
  • From: Southern Florida Gulf Coast
  • 18,255 posts
Posted by SeeYou190 on Saturday, August 12, 2023 7:53 AM

crossthedog
Kevin, I forgot you worked at Home Depot. So to clarify, in your picture the tan/brown/beige is foam insulation board and the pink layers are the Owens Corning extruded foam insulation?

The tan sheets are 1/2" Homasote, which is rarely used in Florida.

The pink is 2" thick Owens/Corning foam insulation. I do not use it on the layout much, but it is the best stuff for making CosPlay props.

After Hurricane Ian when we could not get Sika Plus-3 radiant foam insulation we got 4 by 8 sheets of reflective board and 1/2" Owens/Corning pink board. The prices were very high, but everything was priced high back then.

-Kevin

Living the dream.

  • Member since
    February 2021
  • 1,110 posts
Posted by crossthedog on Saturday, August 12, 2023 11:29 PM

FRRYKid
from what you're describing it almost sounds like you have the type of foam that florists and crafters use for mounting fake flowers.

That's exactly what it is. It was sold as craft foam, but I think it had plastic flowers in mind.
gmpullman
Not something you would ever use around a layout. It decomposes rather rapidly.
Rats. I had a feeling.

@Kevin, thank you for clarifying -- and for providing a nice photo in the first place. That always makes things so much easier.

-Matt

Returning to model railroading after 40 years and taking unconscionable liberties with the SP&S, Northern Pacific and Great Northern roads in the '40s and '50s.

  • Member since
    January 2007
  • 599 posts
Posted by azrail on Sunday, August 13, 2023 1:23 AM

Blue was Dow..now DuPont has bought Dow and changed the color of Styrofoam to gray (more "environmentally friendly"). And the pink/blue/gray foams are extruded polystyrene. Expanded polystyrene is the "bead board".

  • Member since
    May 2008
  • From: Miles City, Montana
  • 2,289 posts
Posted by FRRYKid on Sunday, August 13, 2023 2:28 AM

gmpullman

 

FRRYKid
   —it almost sounds like you have the type of foam that florists and crafters use for mounting fake flowers.

 

 

AKA Oasis floral foam:

https://a.co/d/aQHhzQj

Not something you would ever use around a layout. It decomposes rather rapidly.

Regards, Ed

 

As a side note: That's the wet foam for cut flower displays. There is also the dry foam which is what I was thinking of.

"The only stupid question is the unasked question."
Brain waves can power an electric train. RealFact #832 from Snapple.

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Users Online

There are no community member online

Search the Community

ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
Model Railroader Newsletter See all
Sign up for our FREE e-newsletter and get model railroad news in your inbox!