My random idea for today: could ''Great Stuff'' foam be used effectively for creating the base for mountains and hills?
How would you contain it, forms?
Would you put a layer of something over it, and what?
I'm planning to try that out, initially as irregular river banks that will be carved down/out later.
I have read horror stories from RC folks that shot this into Floats on SeaPlanes & on Custom Boats that have had the growth (Expanding Curing) bow & explode the containing structures! So if you are planning to 'fill' an area, you may want to consider the minimal expanding foam, just for that reason!
Malcolm Furlow uses it to make mountains on his layouts. After it hardens I believe he uses knives to shape it. In one video he said he just paints it.
I tried it. I feel good about the results. This is a sequence of photos:
I'd never heard of anyone else using it, so I was just "winging" it. I applied the foam, then after it hardened, I sculpted it a little (a sharp x-acto knife works well). Then a little plaster and Timberline color, a little foam and I was done.
I think it's pretty slick for small areas.
Phil, I'm not a rocket scientist; they are my students.
I was watching a TV show where they were trying to use it to make a tunnel around a propeller for a small hovercraft. They made a mold out of sheet metal and sprayed several cans of the foam inside. After they let it set overnight they found it did not harden in the middle but turned into a soupy goop.
They did not know why this happened. Maybe there is too much heat build up in larger masses and it causes the foam to break down?
I've used it before and it worked okay. But keep in mind that it can be difficult to predict as it can continue to expand as it cures. Using the low expansion version will help with this.
My biggest turn-off was cost. I found that I could do the same job with other materials that were far cheaper (free in most cases).
You also can't use it in large quantities without running into curing issues. So you need to build it up in layers if you want to make a taller landscape from it. Then you run into my first concern - cost.
Why not just use insulation foam board? If you find a damaged section at Home Depot you can get 75% off.
Cuda Ken
I hate Rust
I used it for my mountain.
I think it's easier to use than stacking the pink foam pieces. You can shape it better, and it gets into nooks and crannys better.
Michael
CEO- Mile-HI-RailroadPrototype: D&RGW Moffat Line 1989
We used it two places.
The first was a glue between the base layer of styrofoam and wood stringers to support the foam at intervals. Stringer, then a little Great Stuff, let cure, a drill and then flat topped wood screw to make sure it don't move.
We thn used it as filler between some existing scenery and the track spline bed. I'm not so thrilled witht he results. Not enough to rip it out, but I should have gone back and smoothed the surface rather than just leaving the cut surface exposed to be painted and glued.
Would I use the stuff again. Yes in places that need cementing, but not in any place that could seen by the public.
I tried it for filling gaps in my pink foam. I found it really messy and had air bubbles like an "Aero Bar" when it dried. I had to use lots of Dap to hide the air bubbles. I really like stacked foam for a base and/or mountains and spray foam can have its uses, but I am not a big fan.
Brent
"All of the world's problems are the result of the difference between how we think and how the world works."
This stuff is messy. Dont get any on your hands. I have used before, for its intended purposes. It seems very unpredictable for modeling applications...I prefer the predictability of pink or blue foam insulation board.
Great Stuff can certainly be messy, wear gloves and old work clothes when you use it.Whatever you get it on, it's there to stay. It you get it on your skin, remove it right away or you'll just have to let it wear off!
With that said, I love the stuff. I got introduced to layout building with foam when I worked for Dunham Studios back in the early 90's. Foam was used for it's light weight and easy formability. We built up the basic scenic forms and yhen most evrything was sprayed with industrial grade foam, the same stuff use to spray foam insulation in homes. One of the nice things about the industrial stuff is that it gets and carvable in about twenty minutes.
All the rough shaping of the topography on my layout was done wiyh pink/blue foam. I used the spray foam to fill in cracks, fill in the steps of the layers of the pink/blue foam and build up smaller scenic forms. You have to wait 24-72 hours for the foam to cure depending on thickness. If you don't wait long enough, you can find yourself at worst, cutting into a gooey mess in the middle or the foam shrinking after you cut in a nice rock outcropping. So, if in doubt, let it sit for 3 or 4 days before shaping.
When applying the foam, run it in half to three quarterinch beads, then run another bead in bewteen the lower layer's beads. Let that skin over and expand for a couple of hours, then you can add another layer. Don't try to make 6" of mountain all at once, you're just going to end up with a gooey mess and lots of big bubbles.
One difference between the closed cell pink/blue foam and the spray foam is that it is open cell, it's filled with thousands of little bubbles - great for insulation, not so much for scenery. Once the foam is carved to shape, I then seal the foam with a mix of lightweight vinyl spackling compound and water mixed to a consistency a bit thinner than pancake batter and paint this (with a brush) all over the foam. This also helps blend the two foams together.
the next step is to paint it after which you can further detail with ground foam, trees, etc.
Some more photos:
I often add very fine paint texture to the paint when painting rocks, it add a grittier texture to the smooth rockwork and looks really good when you start adding washes to weather your rocks.
Jay
C-415 Build: https://imageshack.com/a/tShC/1
Other builds: https://imageshack.com/my/albums
I had some left over after sealing some areas of my basement, and figured why throw it out... I sprayed it in small lumps on a garbage bag and after they dried, I cut them up to make coal loads. It actually didn't work too bad for that - took a bit of cutting and I got two or three loads out of each blob I sprayed. Painted it with acrylic paint and glued on coal.
I saw a video on this stuff and they used crumpled newspaper to create the major shapes, held in place with masking tape. He then sprayed the Insta foam all over it. When dried/cured he carved some of it with a long carving/bread knife to remove the larger blobs. I belive it was finished with a coat or two of Sculpa mold or plaster to get the finish wanted. I thought it looked pretty easy but felt the cost was too high. I use cardboard strips and plaster/gauze or plaster/paper towel then SculptaMold.
-Bob
Life is what happens while you are making other plans!