Mountain Scenary

[Anonymous]

I'm acustomed to building mountains the "old" way by casting rocks with rubber molds onto a base generally of newspaper and plaster. Can someone explain to me their technique to build a mountain with foam ? How do you "finish" the foam ? Is the foam a base and just the rough beginning and then finished with molded rocks ? or are their other techniques besides using molded rocks? Thanks

[orsonroy]

There are several ways to use foam in building mountains. You can stack it and carve it, stack it, carve it, and cover it with plaster, or use the foam as lightweight supports for traditional scenery (screen wire and plaster).

I prefer stacking it and carving it. I generally use wood glue to bond the pieces of foam together, but any foam-safe adhesive will work (believe it or not, the most often recommended adhesive, Liquid Nails, specifically says on the package that it is NOT intended for foam-to-foam bonds. It's not a good bond). The downside to gluing foam together is that, because it doesn't allow air to circulate, it takes several days for the glue to dry completely. Using foam-safe rubber cement solves this issue, but is an expensive and uncarveable alternative. Drying foam usually requires something to hold it down until the glue sets. Clamps, weights and bamboo shish-ke-bab skewers all work well for this, depending on the situation. I've even used pop cans.

Once the adhesive's dry, start carving. There are a lot of hand and power tools that can be used for this step, but I prefer simple hand tools: boxcutter knives, old bread knives, hacksaw blades and a Stanley Surefoam rasp (the small one). Hot knives and hot wire tools can be handy, but I find them to be slow and of little real use (some people get great results out of them; it's a personal thing, I guess). A wire wheel in a power drill works wonders, but ONLY use this technique outside! Use the bigger hand tools to rough out the basic shapes, and use the smaller tools to add detail. Be sure to avoid flat areas and sharp, unnatural angles in your carving, and have a shop vac handy to clean up. A sanding block and plenty of sandpaper also works for some situations.

As for simulated rocks, you can still use rock molds on foam, gluing them to the foam with wood glue, but why bother? Film and theater set designers have been using all-foam scenery for decades now, and if they can carve a chunk of foam into a cliff face, so can we. Use plenty of sharp knives, some dental picks, screwdrivers, and a wire hand brush (the ones that look like mutant toothbrushes), and practice on some scrap, and you can carve any rock feature you want.

Foam can be painted with any latex paint. I prefer a base covering of the cheapest indoor household latex paint I can get my hands on. Some hardware and paint stores sell seconds of mis-mixed paints for $5 or so. Find something that's close to what you're looking for, and go for it (I refer to it as looking for something that's "-ISH" colored: brownish, tanish, slateish...) I've found that for detail painting work (especially rock outcroppings), the cheap craft paints work the best. They can be used full strength, or thinned with water and alcohol to create stains and washes.

Using a covering of plaster or plaster-impregnated cloth over foam is wholly unnecessary (IMNSHO), and adds cost and time to the endeavor. Plaster is brittle, and will crack and shatter when impacted. Foam, on the other hand, will dent a bit, but will otherwise be OK when impacted. And a few random dents here and there won't hurt anything. Some people will claim that foam, being a "fire hazard", requires a layer of plaster over it to make it safe. Hogwash. In general, US building codes will require a minimum of 1/2" of plaster or gypsum board over any foam being used in home construction. Adding that much plaster to foam negates any benefits that come from using the stuff in the first place. And industry MSDS safety sheets and fire tests conducted by the University of Oklahoma report that the flash point for wood is lower than that of foam (ie: wood will burn before foam), and that household carpeting emits more poisonous fumes than burning foam (not that burning foam is safe, mind you). The point is that foam, used normally, is perfectly safe and benign. You don't have 1/2" of plaster covering your couches and carpeting, do you? Fumes from burning furniture and carpet kill people in this country every day; I've yet to hear of anyone killed by the fumes from a burning foam layout...

Finally, about the mess carving foam creates. We participate in a messy hobby. Yes, when you carve foam, you get little particles of little pink (or blue) snow everywhere. It's dry. It cleans up quickly with a shop vac. Plaster, on the other hand, is a wet, clingy, messy substance, that will wesult in your wife throwing a frying pan at your head if you get half-dry plaster into her carpeting, or will result in you losing a clump of hair trying to get it off of you. Working with plaster requires a prep time and cleanup time for all your tools and yourself, in addition to cleaning up the layout, which takes much longer than just vacuuming up some foam.

[Anonymous]

Thanks so much for the detailed answer, so bottom line detail the foam with "tools" and then just paint , obviouslsy then can add ground cover trees or whatever if dress it up. Thanks again

[rexhea]

Another Thanks "orsonroy. I sure know what you mean about the mess from plaster. I just completed my first mountain using the basket weave cardboard with plaster. Now my work area looks like a ceramics hobby shop. YUK!

I have many more to go and after reading so much about using foam, I'm going to give it a try.
Can you use a Glue Gun on low heat??

[orsonroy]

QUOTE:
Can you use a Glue Gun on low heat??

Actually, I'm not sure. I've never tried using a hot glue gun on foam, but I'm pretty sure I've heard of people who have done so successfully. The only problem I see is that the hot glue dries fairly quiclky, meaning you'd have to work fast. I'm not sure how well it'd work on large sheets of foam, due to the fast dry. I'd think a combination of wood glue (or other glue) in the middle of a sheet, with the hot glue on the edges, would work the best.

[snowey]

Also, only use latex or acrylic paints on foam, as the solvent in other paints, like enamel and oil paints, will eat right through the foam, creating a mess.
Ther was a good article in MODEL RAILROADER sometime back in the 80s showing how to make lightweiht, flexible rocks by using foam rubber thats been partiely cut, then ripped into peices, glued to the surface (again, only use water-based products with foam!!!), covered with latex calk and ground foam to give it texture, then painted.

---

This past June, MODEL RAILROADER had an exellent article showing you how to use foam.

[Anonymous]

Hot glue on foam, If my memory serves me well, it melted the foam.
As far as mixing plaster and hydrocal being messy:
I now mix my hydrocal in a plastic zipper bag, the freezer type not the thin ones.
Pour in the water, add the hydrocal, zip it up fold over the top for safe measure, hold on and shake it up.
From there you can just pour into molds.
I also have poured into styro cups and then brushed it onto my layout as needed.
No fuss, no clean up.

[Anonymous]

I would like to know wher I can buy flexible rocks

[nbrodar]

WS makes special low-temp hot glue for foam, but I've never used it.

I stack the foam, up wedding cake style glued together with yellow carpenters glue. When dry, I carve the foam using knives, rasps, and surform tools. Then I slap on a thin coat of pre-mixed drywall mud, followed by latex paint, dark green for forested mountains, or tan for other areas.

I cast rocks from plaster, and use most drywall mud to stick them to the foam. Then, I blend them together with non-shrink acrylic spackle. Finally, I color them with acrylic craft paints.

Nick

[Anonymous]

Thanks Nick
With your letter I have an idea how to do it

[Anonymous]

Thanks Nick
With your letter I have an idea how to do it
Jose Manuel

[Anonymous]

actually I started to use foam but it was a mess and a pain so I took it down and waen to the hardware store and bought some poultry or (chicken) wire and got it in the shape I wanted it and stapled it down and then paper mache it then scenery ok

[bogp40]

Ceramic tile cement works excellent for bonding foam. A notched trowel to spread the adhesive will allow air to be trapped between the layers to aid in drying. This also give a suction for initial tack. This adhesive is fairly cheap and water cleanup. It works for bonding foam to foam, plaster to foam plaster to plaster , wood to foam and plaster to wood. If this product allows tiles to stay put in your shower for 30+ years it should hold a layout together.
Bob K.

[Anonymous]

Well back to the Hobby Lobby........

I bought a low temp glue gun at Hobby Lobby and it works great on foam. I used it to glue down all my Woodland Scenics risers and inclines.

I can't offer much to the original poster as I did my layout with newspaper and plaster.

[jlrc47]

This might help you with a cliff or some detail and its cheap . http://www.pacificcoastairlinerr.com/more_rocks/
Joe

[Anonymous]

I'm just getting started and I've used white glue to glue down the different layes and have not found that the drying time is all that long. I cut my mountain outside and used brick to weight down the stacks f foan after I cut out the general shape. I also use sheet rock joint compound after the carving and general shaping is done. Need to layer it on thin, or it will crack. The paint will fill in any small cracks, so a lot of attention to this aspect is not necessary in my opinion. The joint compound can also be sanded. .

[tomikawaTT]

One unmentioned advantage of foam over a plaster upper surface is the ease of installing trees, mountain goats (or climbers) and such. All you need is something pointy on the bottom; stick it in and you're done. No need to jackhammer the surface or foul a drill with plaster.

[Medina1128]

As far as Liquid Nails goes, I use the Liquid Nails for Projects and find that it's dry in 24 hours, and it's fairly cheap. I get it for $1.32 a tube at Wally World. I stack the foam, then carve it. If I'm modeling rolling hills, I paint it with thinned acrylic latex, and while the paint is still wet, I sprinkle on sand and ground foam. When the paint's dry, I add more ground foam using a spray bottle with a 50/50 mix of wet water and white glue (wet water is water with a few drops of liquid detergent added).