Foam in a Can: anyone use it to fill gaps in their scenery or roadbed

[Fergmiester]

I was looking at the MESS and looking at some gaps along the sides of the elevated sections of road bed and the board. I figure I can build this up with chunks of foam board, plaster or paper mache. Then it dawned on me Why not expandable foam insulation in a can. I've used it before for putting in R/C boats as reserve floatation but before I do this I thought I'd check for horror stories.

Regards
Fergie

[Anonymous]

There have been threads about this topic already, I suggest doing a search.

[orsonroy]

I have a foam-based layout and had the same thought about using foam in a can. In general: don't.

It works just fine to fill in gaps between foam pieces, or between foam and the backdrop, and I've even had some success in rounding off corners by making a duct tape form and filling it in with foam in a can, but it's absolutely horrible for making scenic contours. You can't really regulate the expansion rate, so you don't know what you'll end up with until it's hardened. Once it's done curing, you'll have a blobby yellow zit on your layout that you have to carve into a realistic shape. you have to use knives and hancsaw blades, because the stuff is too soft to use a Surefoam tool on. Once you start cutting into the blob, you'll notice that it looks like Swiss cheese on the inside, with lots of big holes running through it. That's fine if you're modeling Okinawa or Tarawa circa 1945, but no good for a model RR.

Stick with sheets of foam for scenic work.

(Oh, I've used Great Stuff and the Dow stuff for my experiments. Don't even consider the Dow crud. It "hardens" to the consistency of dryer lint, and is completely useless for modeling purposes)

[MAbruce]

I have used this product only as a scenery base for plaster soaked paper towels. However, I only used it once as it proved to be too expensive for what I was using it for (there were many other cheaper alternatives).

For a gap filler, I suppose it would work. I would recommend that you use the low expansion formula for those areas you have to be careful with.

[Anonymous]

I had very good luck using can foam. I have a grade that curves up to a second level and I didn't want the hassle of using plaster. So I made sure everything was secure as this stuff can really expand and filled the gaps. After it was cured I simply carved it with an X-acto knife and an old razor saw. I was happy with the results. I wouldn't suggest using it to make a mountain or to fill large openings but I was pleased with it.

Jeremy

[vsmith]

Be Carefull, a little bit of this stuff expands ALOT! more than you might think. I used it to fill gaps in my benchwork. I used the least expansive stuff and it ballooned up 3X what I expected, and there is stuff that will go 5X or more.

This stuff is SOFT. Dont plan on carving it, or using it to support anything. I cut my stuff with a large Olfa knive blade. and dont cut it for 24 hours or it will stick to anything you stick into it. Dont let any get on your fingers or cloths, it will not come off.

Finally once you start using that can, use it all or it will be out of pressure the next day. also dont let an unused can set around for 3 months, it too will lose pressure.

[Anonymous]

I don't think you should even think about it. Great Stuff is the messiest stuff in the world and I can't imagine using it on my layout!

[Anonymous]

Being in the thick of layout-building, I will share some very recent experience. ( I think I have commented on this in a previous thread). Great Stuff foam is a wicked cement. I have used it both to glue track to foam insulation board and to glue 2" foam slabs together to make foot-high moutain ranges. I also used it early-on to glue my blue foam roadbed to my OSB sub-roadbed. I use it because it is the best thing I found. It cures fast and won't let go. But I think it is too expensive to waste on filling voids. Besides, it expands uncontrollably. Neither is it a good choice for visible surfaces. It does not make realistic-looking rocks or anything else. Just today, I was filling in the spaces around my curved facia boards. I used wadded newspaper as a base, then filled in with colored plaster. If you want to fill spaces, colored plaster is both the cheapest and the most versatile solution (IMO). Anyone want more info on colored plaster, ask.
Bryant

[Jetrock]

I tried it for a diorama I am building--I made a mountain contour out of Styrofoam glued together with Liquid Nails, and sprayed Great Stuff expanding foam onto the Styrofoam to provide the mountain shape. It grew grotesquely, and I discovered to my horror that the Great Stuff's expansion had actually shoved the Styrofoam slabs apart, resulting in a cockeyed mountain. Some utility-knife surgery got things under control but it definitely showed me how hard to control the stuff is--and yes, the stuff sticks forever to ANYTHING. I ended up carving away what didn't look mountain-like and covered the whole thing in Sculptamold.

[darth9x9]

There are different types of the expanding foams. There are 3x and 5x but there is also 1x which is recommended for doors and windows as to not distort the frames causing them bind.

You could also go the cheaper route of paper towels or newspaper balled/twisted/crumpled up to fill the voids and then put a layer of plaster soaked paper towels or plaster soaked newspaper on top. I have seen people just use ground foam over the balled up material.

One other option is plaster gauze which is available from medical suppliers for $2 a roll - much, much cheaper than Woodland Scenics.

[Fergmiester]

QUOTE: Originally posted by darth9x9

There are different types of the expanding foams. There are 3x and 5x but there is also 1x which is recommended for doors and windows as to not distort the frames causing them bind.

You could also go the cheaper route of paper towels or newspaper balled/twisted/crumpled up to fill the voids and then put a layer of plaster soaked paper towels or plaster soaked newspaper on top. I have seen people just use ground foam over the balled up material.

One other option is plaster gauze which is available from medical suppliers for $2 a roll - much, much cheaper than Woodland Scenics.

Thanks for all the input guys

I normally build up with styrofoam, then I build, where needed with paper mache. I was not aware that plaster gauze was so cheap. And I wasn't aware that foam came in different rates of expansion. Again I wouldn't normally use foam but I have a few areas which are narrow, deep and need stability and filling this is why I'm considering foam.

Regards

Fergie

[der5997]

Fergie: What vsmith says is absolutely right. The expansion RATE is another consideration, because way after you think it's all done, you come back, and there's more. Do you remember the movie "The Blob" ? I used this foam to fill in the Atlas viaduct sections, for sound reduction. Works really well for that, but I had to keep cuttiing off the loaf shaped mounds that kept forming on the bases of the piers.

[darth9x9]

der5997 (John),

That's why I recommended the 1x expansion type that is made for doors and windows so it won't distort their frames and cause them to bind. Once the 1x stuff cures, it feels like a soft marshmallow. I used it (and the 3x) throughout my house last year when I built it. The 3x was great for voids in the walls like those in bay windows. The 1x was used on every exterior door and window. I think the name of it was "Great Stuff," which it is!!!

[Anonymous]

I uesd the 1x type foam on my layout. I did forget to mention that. oops. Looks like I'm pretty much the only one that has either used or like using it. I had no real problems with it except the fact is does stick to everything. I just kept a bowl of water handy if I needed to guide it any. I simply dipped whatever I was going to use in the water and had no problems. Just me though. Here is a picture of my layout where I used the can foam.



From the blue Rock car all the way up the cut was filled using can foam. I cut it back and used hydrocal and rock castings. Oh and believe it or not from the bridge down to the BN car on the other side of the train, is only half plaster. The rest is exposed can foam carved and painted. The left side of the train, with the grass strip going up the hill to the bridge is also all can foam. Remember that I only used it to fill gaps. The bulk is insulation board and 1X4's for support.

Yes this stuff can be difficult but it can also be very useful. Also just me.


Jeremy

[der5997]

Jeremy: Actually I enjoyed using the stuff, and will again. It did just what I wanted it to, but a bit more than I expected! I'm sure before all the scenery is done. Next time I'll look for the 1x. Never stop learning!
Thanks for the water tip. John.

[CBQ_Guy]

Fergie,

A friend of mine used it against the backdrop way in the back on top of some hills to replicate the look of rolling terrain. He painted it green and glue on tons of Woodland Scenics bru***o simulate distant tree tops. Doesn't look half bad.

Just realize that this stuff is REALLY sticky so possibly use some latex gloves while working with it. It comes in high expansion and low expansion types. I think what I'm calling high expansion may just be the regular type, though.

Try it on a small section as an experiement and see how it goes...

[Anonymous]

Okay, I will try to provide some insight here. Definitely go for the least expansion you can find. I have used a latex-based foam filler made by DAP called DAPTex fot filling a large space between pieces of foam on a small diorama. After I applied it to the needed areas I put a bag on my finger and basiaclly formed the foam. When it had cured, it was soft and white like a marshmellow. I was able to do the fine forming with a wire brush on a Dremel. When I was ready, I painted the entire diorama with flat tan latex paint. I noticed that when the paint dried, the paint shrunk a little, taking the foam with it. The foam was pulled back around the edges about 1/8". A few years ago I used the brand name Great Stuff for a project. It dried yellow and hard and alowed me to carve it. Both of these foams, when cut, are found to have a texture filled with many little bubbles because it is FOAM. The blue and pink foam board was made by putting foam into I believe mold-type objects and compressing the foam so it is NOT filled with little bubbles so it is more dense and a better insulator. Granted, if you are using this foam filler as a base for carving rocks, these little bubbles will cause a problem. I don't know if this foam can be cut with a hot wire foam cutter will cut this, but if it can, that would solve all irregular texture problems. If this foam is going to be used as ground with ground foam or a similar material over it, then the tiny bubbles will not be a problem because they will be covered and will not be visible. Personally I would go with Great Stuff because it cures hard so it will not pull back when painted.
Basically I say that this material is a great land-form filler, especially Great Stuff.
Reed