# Using expanding foam and shaping?



## niceguy

Anyone ever tried working with expanding foam, then shaping it once it cures ?

It seems like such a messy way to do things, but it does give you the freedom of shaping anything and anyway you like.

Just curious if any of you have tired it and your experience.


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## Lorne

I've used it at work but never for a layout. I can see it being more of a hassle than help. When it's wet it sticks to absolutely EVERYTHING and hard to cleanup. 

One idea I read about in a train magazine showed this guy using that blue styrofoam insolation (2 inch stuff). Cut it to rough sizes and variouis, then placed them on edge to create a rocky type mountain. It'll be alot easier to cut then expanding foam and easier to clean up.


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## niceguy

I am worried about the clean up too! I remember spraying it once to seal a door and the stuff was just stuck everywhere. I thought maybe if it cured it would be a smart way to do things.... 

i may look into this blue foam you're talking about.


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## ptg4n6

Try the blue extruded foam.
It can be purchased at most home improvement centers and comes in 1" and 2" thick.
I have just completed my first layout and the foam was easy to shape and not terrible to deal with regarding clean-up. A small shop vac works very well if you have one.
NOTE: Make sure that when you secure it to your benchwork, or when stacking pieces for sculpting...use a FOAM COMPATIBLE adhiesive. If you don't, the adhiesive will distort the foam significantly.
I hope this helps...


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## alfalfa

I made my first mountain with GREAT STUFF. That is what you are talking about. I liked the finished project but in the future I will go with 1" - 2" thick foam insulation sold in sheets like the above advice.


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## ntrainlover

Your best bet is sheet foam.


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## sptrains.com

I still like the whole woodland scenics system as far as easiest to use, and least mess. One note about expanding foam, make sure the room is well ventilated, and no open flames, under the right conditions that stuff can form cyanide.


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## ntrainlover

What I use is That 1 inch foam board, I shape it, then I glue it. After a while I cover it with plaster cloth to stregthen It. A little while later I com back and fix it with sculptamold. Then the woodland senics stuff goes on. This is how it looks.


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## sptrains.com

Cool, it could be the picture but it looks like your curve has a nasty kink in it.


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## ntrainlover

no, there is a little tiny piece of straight in it.


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## T-Man

*Liquid Nails*

[ NOTE: Make sure that when you secure it to your benchwork, or when stacking pieces for sculpting...use a FOAM COMPATIBLE adhesive. If you don't, the adhesive will distort the foam significantly.

I heard through a crafting source, that you can use Liquid Nails. It's a tube you can use with a chalking gun and easy to apply.
Model airplane glue is definitely OUT, unless you need to make a crater.
Don't say I didn't warn you.


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## sptrains.com

I think liquid nails would be way way overkill. Elmer's does the job fine. You really don't need a whole lot of glue, since 99% of the forces will be compression. And Elmer's will hold well under any of the shear forces you'd expect with a layout. I did all foam and it's constantly being played with at the store and by my 3 year old when he visits. No problems at all.

Josh


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## Lownen

sptrains.com said:


> I think liquid nails would be way way overkill. Elmer's does the job fine. You really don't need a whole lot of glue, since 99% of the forces will be compression. And Elmer's will hold well under any of the shear forces you'd expect with a layout. I did all foam and it's constantly being played with at the store and by my 3 year old when he visits. No problems at all.
> 
> Josh


If you mix Elmers or other white glue with water 50/50 or there abouts (64/36 should be fine) you can apply it with a brush and get a nice even coat on one surface to bind the next layer too.


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## Don Chovanec

Another negative on the expanding foam, it has a pretty powerfull push and could just rip apart your frame if it got into a crack. I saw something that I am going to try. I is a light green foam block about 4 inches square and 12 inches long. It is used for flower arranging decorating and is a fine grain. It does absorb water but I dont think it swells so I am not sure what will happen I may have to wrap it in plastic wrap but hey ya gotta try. Anyone tryed this. Also at this store Michaels they had an electric slicer for styrofoam that looks like a cooping saw. for 7.99 I am going to find out what the heck that does. I have used the foam sheets mentioned and some wire frame papermeigh ah I can't spell it. Paper sheets soaked in plaster and had some interesting results. I am always looking at how can I use common things that are also cheap. The cheaper the more I can use. I have used that Sculptmold and it was great but costly to do a whole lot. Of course I am trying to think downsized but I have such a grander view looking up!


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## Don Chovanec

Wow I cannot type fast enough or maybe I talk too much . . . Yeah that must be it. The thead is change by the time I post to a new venue!!!


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## stationmaster

Lownen said:


> If you mix Elmers or other white glue with water 50/50 or there abouts (64/36 should be fine) you can apply it with a brush and get a nice even coat on one surface to bind the next layer too.


Exactly what I normally use. Another good product is the craft "Spray Tack", a 3M product I believe. It is a tacky spray glue meant for foam projects. Bad part is it is like a contact cement. You'd better be right the first time. Ain't no "do overs".


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## JPIII

I use a lot of expanding foam......it's the cat's ***, IMO.
Clean up is easy with lacquer thinner......even the applicator nozzle (tho Not on your foam) but have some paper towels standing by for wipes of spillage. I coat the stuff with light weight spackling compound (suitably thinned for workability). The LWSP is not very stout but it sands & shapes easily (but you don't want the dust in your nose). 

The best EF is the windows/doors stuff. *Mostly* it sets up at around 3X the applied size and free of voids. 

Wanna build a mountain? Lay down a blob of EF. Let it set for a couple hours, lay down another blob....keep going till you reach the ceiling, let the whole works set up for 24 hrs. cut to shape with a roughly sharpened knife (bench grinder/decent file is gud). The EX IS compatible with blue, pink, & white foam and WON'T push your layout apart. Save your EF drop from cutting. 
Great for undulations in flat surfaces....just glue it down & carve.

5-7 bucks a can at about any hardware store.


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## tjcruiser

Our member Swiggy has had great success using expanding foam to construct his southwest themed layout. Here's just one of his many threads ...

http://www.modeltrainforum.com/showthread.php?t=9347

TJ


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## Carl

Expanding foam was tried by a local club - NASA N Scalers. They shoot the stuff out of a can and before they could get to it to shape, it hardened. Made a really mess.

Liquid Nails and caulk works great for securing foam.....as noted above, please make sure you use water-based Liquid Nails or caulk. Petroleum based products will dissolve foam.


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## JPIII

I got a care package of tunnel portals today and have a design error to fix.
I'm waiting for the EF to cure as we speak......BTW, there are no brain surgeons in my family.. Tomorrow I'll carve to fit. I've suffered no degredation of the blue foam/EF interface. I got the EF tip from a fella named Doug in Grants pass, OR. He's one sharp fella. .......


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## Southern

look at the date on the first post!


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## JPIII

Here is some of Doug's work.

http://www.allscalelayouts.com/R/Aspfiles/DetailPage.asp?Xfer_Code=80001061


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## JPIII

Southern said:


> look at the date on the first post!


Ayup, that's how far back I had to go to find much on expanding foam. 
Anyone (IMO) that's building a layout for the first time needs to have this in their repertoire.


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## gunrunnerjohn

FWIW, I use the expanding foam, but not for this purpose. I can't imagine using this and actually working it before it hardens.


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## New Berlin RR

Southern said:


> look at the date on the first post!


hey Southern all I got to say is in the picture


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## JPIII

New Berlin RR said:


> hey Southern all I got to say is in the picture


Nothing like a little geek humor to add to the knowledge base.


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## T-Man

Expanding foam is great for filling voids. If you have a carboard crisscross mountain collapse. The foam can be used to support the interior.


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## gunrunnerjohn

Filling voids is what it's good at. Shaping it I don't see as a practical use.


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## beachbum

gunrunnerjohn said:


> Filling voids is what it's good at.


I've also used it to replace fiberglass insulation in floor joist boxing in my basement when Mr Mouse and family had built a nest in there. Hard to judge how much it's going to expand.

Might be worth an experiment - maybe use PVC for a tunnel liner on some scrap plywood and foam up over it? Wonder what you could use for a curved tunnel...


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## New Berlin RR

JPIII said:


> Nothing like a little geek humor to add to the knowledge base.


Oh...you wanted geek humor....please hold...correcting 


Correction complete


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## Carl

A little bit of the expanding foam goes a long way.


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## gunrunnerjohn

beachbum said:


> I've also used it to replace fiberglass insulation in floor joist boxing in my basement when Mr Mouse and family had built a nest in there. Hard to judge how much it's going to expand.
> 
> Might be worth an experiment - maybe use PVC for a tunnel liner on some scrap plywood and foam up over it? Wonder what you could use for a curved tunnel...


My use of expanding foam is similar. I've used it as a convenient method of insulating cavities as well. I don't think it carves nearly as well as the blue or pink form, which I'd pick for fabricating something over trying to do it with expanding foam.


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## swiggy

This is all expanding foam covered with plaster cloth. i still need to do some finishing work, but i'm really happy with the results:thumbsup:


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## gunrunnerjohn

Well, that looks great, I would have thought that would be a lot of effort to properly shape it with the expanding foam. What brand do you use?


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## sstlaure

Once the expanding foam cures solid you just cut it with a saw blade/file just like the 2" rigid polystyrene foamboard. Once I get my rough forms in I intend to use this to fill the gaps and smooth out the contours and cover with plastercloth.


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## gunrunnerjohn

I'll have to keep that in mind. I know you can cut it, never considered it for this use.


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## JPIII

That looks good, swiggy. Be careful tho, this thread has trolls lurking on it.

I no longer use the plaster cloth over any foam, I just go straight to plaster (light weight Spackle, actually). It took a bit of thrashing around to come up with which coating works best for me. The stuff ain't perfect, it's too soft after set up, but a coat of paint firms it right up. It does sand and shape nicely. It does crack when applied thickly but that is easily fixed with a daub of the Spackle on your finger rubbed into the crack.

I did a better job controlling the EF on the other portal. Too much wastage of the first......and less cutting/shaping. .....


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## swiggy

gunrunnerjohn, any brand works just fine. wally world even has their own brand now.
jpIII........superb use of the foam:thumbsup:

in one area, i let the foam dry for 15-20 minutes, then compressed it making sure none got on the tracks (it will ooze). it made a nice jutting butte


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## gunrunnerjohn

Another arrow in the quiver, after using it for construction projects, never considered it for this use.


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## JPIII

gunrunnerjohn said:


> Another arrow in the quiver, after using it for construction projects, never considered it for this use.


There it is.
I chose a pick-up load of blue foam over a pick-up load of EF for the bulk of my layout. Swiggy did the opposite. I got maybe a grocery bag of EF. The 2 methods meld together quite nicely. The EF seems to be a time saver in many cases.....I'm not even gonna try to compare the 2 for a cost analysis.

I've used the EF in a few oddball places over the years, well beyond it's intended usage. One of which was the inside of the thin fiberglass fenders of my race car. A good coat of foam protected them from the impact (star bursts) of rocks picked up by the slicks & flung all over hell & gone......now that was a messy job. I got most of the glop on the fenders but a goodly percentage on me. I think it also helped bond the FG to the sheet metal.
That glop sticks to everything.

Next time I use the glass coffer dam trick, I'll hit the glass with some FG mold release first.


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## stationmaster

A few of my dioramas are courtesy of EF. Didn't use it much on the layout, though. Found it to be a bit fragile.

Bob


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