Spray Foam question?

Just a thought, and I haven't been here in a while so this has probably been addressed before. Has anyone tried using the spray foam that is usually used to insulate windows. I use it all the time for that purpose, and it seems you could contour and slope it into rolling hills etc. It's easy to cut when dry, it sticks to everything and it's super light. I use a Japanese saw to cut it and you could probably use a sureform plane to shape it. I know that UV light effects it but if its painted or covered that should not be a problem. I'm not sure what happens to it once it has expanded because in my application it's behind trim.

Just wondering.

Reply to
Loading thread data ...

The problem is ..... that it "sticks to everything". Very hard to control, but it's been done. Me, I don't use it.

Reply to
Wolf Kirchmeir

If this is the product I've seen under the name "Great Stuff!", then my answer would be yes. I haven't used it myself on my layout, but a few years back a friend with a basement sized PC and predecessor layout used it in some set back, corner areas over some sheet foam contour hills screwed into the wall and crisscrossed with masking tape, IIRC. For some reason I can't remember what he covered it with.

However, he applied small blobs of the spray foam all over the top to give an irregular, rolling surface. After the foam dried he painted it all a dark green. Then he dumped tons of Woodland Scenic green "Foliage Clumps" all over it and applied copious amounts of "Scenic Cement" sprayed over it all to set the foam. Man, did he use a ton of bags of the WS foam. I suggested to him that they should also sell it by the bale, or at least in five gallon buckets, like sheetrock mud. Since then, Scenic Express sells it in much larger containers in addition to the the original, small bags of the past.

Anyway, like I said, it's been four or five years since we used the spray foam and it seems to work well as an undulating land form to put under the foliage clumps, which would resemble tree tops in the distance, using more detailed, modeled trees with trunks, branches, etc. in the front.

Hope this helps . . .

"Paul - The CB&Q Guy" (Modeling HO In 1969.)

Reply to
The CB&Q Guy

yes it did. I thought it would, but wasn't sure how it held up outside in the open air. Yes the product is called Great Stuff and there are others I have used similar to it.

thanks again, Rich

Reply to

You can buy expanding urethane in bulk in various strengths -- i.e.

formatting link
Save yourself a bundle over spray cans if you use a lot.

Reply to

Avctually there are several different "spray foams" and most are different density spray urethane.

For a much better deal you might want to check with an insulation contractor or imsulation contractors supply house. If you are lucky enough to know a cold storage contractor you can get some left-overs from job sites.

Some of the other brands are Versi-foam and Handi-foam.. Any type of spray urethane with finish with a "skin" on it. Once you break the skin and start to shave it or carve it you will get dust everywhere. Some people tried using the block & slab urethanes for a base for scenery years ago but realized the problems with the dust. The fact that hydrocal can be brushed on for a sealer helps.

I would advise against using a 2 part pour foam. So many factors come into play such as temperature and humidity. If you do use the A & B mix be sure to do some VERY SMALL test batches to get a feel before going large. One of the worst & funniest phone calls I ever received was froma man asking how to stop the foam from expanding. He had bought a

5 gallon can of each ( A & B ) to mix some to pour into areas of his boat for flotation. I had explained to test it first with just an orange juice can of each in a large bucket so he could get a "feel for it" but instead, the idiot pours 5 gallons of A and 5 gallons of B in a washtub under his carport. As the foam expanded it crushed the boat against the outrside support poles of the carport before pushing the roof off of the carport.. Make sure to test it in small amounts before getting into trouble.

Some of the guys that worked for us would use the big spray rigs that took the mixes from 55 gallon drums when a cold storage job called for urethane. . At the end of a day they would make sure to clean the gubs by pushing all that was left in the hoses out into piles. There would be these giant mushrooms about the size of an old VW beetle. If you know enough people with truks it's pretty fun to load a bunch of these into trucks and place them on someone lawn in the middle of the night so you can watch all hell break loose in the morning.

Also, if you just pass the spray over an object, the foam will expand but keep the shape of the object. The guys always sprayed hard hats for people on the jobsite. imagine a hard had that fits your head but it's about 8 times larger witjh lots of insulation from the sun.

Ok, I' know this thrills you but now I'll explain the difference between extruded and pre expanded polystyrenes............................excited ?

Just remember, Styrofoam is a trademark of Dow Chemical and it's blue ( Amaco's is pink ) and is an extruded polystyrene. Pre Expanded polystyrene is also known as beadboard because as you break it, it breaks into foam beads that float around. The drink cups are NOT Styrofoam, nor are the ice chests or coolers. Those are pre-expanded polystyrene.

I*'ve seen some people say that the true styrofoam is not rigid enough in 2" thicknesses. They might want to try Styrofoam HL-40 / HL-60 or HL

120 ( if I remember the numbers right) Normal Blue Styrofoam SM ( smooth material) or SE ( square edge ) has a nominal density wehere the HL series are designed for insulation cold storage wearhouse floors and are a much greater density.

Find a cold storange warehouse under construction and talk to the contractor. They will be happy to give you a pick up load of scraps for free. It's costs them to send it to the dump because of EPA. Buy the foreman a case of beer and he'll send one of the guys to loas the truck for you.

Reply to
the OTHER Mike

thanks again for this info I have saved it for later review.


Reply to


Like "Mountains in Minutes"

Hehehe... Paint them like Oompa Loompa's first though...

In that vein i've also seen people use this stuff as molding material for "one shot" molds


Me too Mike, Thanks a heap!!!

Reply to
Big Rich Soprano

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.