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I am taking on my first real foam landscape project - would like some advice.   I must first tell you my resume includes 2 maybe 3 you tube videos.   While I feel pretty good about how I am going to do it - I really would like some input on what it should look like.   I have added some pics to show what I am doing.  

I will have a river under the bridge that will dump into a lake -  the lake will be on the back side of the bridge     What you see the “front” side with the foam     Just trying to figure what the terrain should be.    Looks like steps down now.  

One specific question

 Should I build the scene in place or take it out and glue it to the table top when it is substantially complete?

appreciate any thoughts, tips and ideas 








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Original Post

Answering a question that you didn't ask, but... The pink foam has a film on it that you want to peel off before painting. I use Liquid nails to glue the layers together.

I built one piece with Luan backing. It stiffened it up, but that is the only scenery piece that I have built that warped. FWIW, I like building the scenery as separate pieces.

Last edited by Gilly@N&W

I just finished a major landscaping project involving hillsides, a bridge, and a river.  Gilly's right.  You need to remove the film and use Liquid Nails or Loctite PL 300 Foam adhesive.  I've used spackle to make the slope.  I've also used the Great Stuff foam and low-loft quilt batting to make a larger hillside.  There's a YouTube video by a member here, CJ Ambrosi, you should check out.   Both methods work fine.


In my Halloween layout build thread, I did my first ever foray into foam building.  It was a lot of fun.  For the layers that got stacked, I didn't both stripping off anything.  Use Glidden Gripper (it's a primer) to stack the foam pieces.  Other adhesives don't work because they need air to set up.  

For what you are doing I would make the pieces removable only because they would be easier to decorate then reinstall.  

Lots of options for texturing and surface cutting.  A hot knife is great because it's flexible and doesn't make a mess.  Other tools are utility knives, razor blades, hacksaw blades used by hand, rasp, and my personal favorite, a pumice stone.  (Yes the kind you can use to scrub callouses off your feet.)  

Painting can be anything, once you get a good foam compatible primer down.  Since you are doing a water's edge, I high recommend you keep watching those you tube videos about shading layers of paint.  

The other option is to just leave the "steps" in the foam and simply cover them with a different material to form the final contour. Possibilities are plaster (or glue) soaked paper towels, strips of wide masking tape, paint-soaked cloth, and so on. I like this "two-stage" approach--you use the foam to establish the rough contours, and a more malleable material for the details.

I am a big fan of building modules on the workbench and just dropping them onto the layout. Here is an interesting example. It is actually a lift-out "plug" used to cover a maintenance hatch:

modules 2modules 1NF 1


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Last edited by Avanti

Okay my  plan is build this in sections on the workbench the put them together on the layout like a puzzle and connect them once they are on the layout.   

What you see here is what will be the river under the bridge that will dump into a lake.  The wide side will bend to the right as you come out from under the bridge and dump into a lake the other side will hopefully just disappear into the landscape

1.  Does that seem like a reasonable plan.

2.  I can use the plaster cloth to cover  or plaster of paris or other? - any preference here?

3.  Anything else I should be considering at this point.








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An old (1980's) idea for simulating water is Artist's Gloss Medium.  Available at Hobby Lobby, art or craft stores.  Being water-based, it is compatible w/ foam and everything else.  Comes ready to use in a bottle.  Paint the stream bed on the base- painting darker in the middle simulates a deeper stream, gradually lighten until edge matches color of the surrounding"dirt".

Then  just pour, let it run over the terrain as would a stream.  It takes a day or two (if a thicker pour) to cure.

Here's some pink foam that I started as a primer for foam scenery.  Admittedly, it's N-scale, but scale is immaterial - it's all the same, really.310

A piece of 1" thick pink foam, with 1/8" cork roadbed and Code 80 Atlas N-scale track glued to it.  A felt-tip marker shows where a road crossing over the track will be.  The rest of the pink foam surface has been grated and sanded down slightly to offer some scenic relief to the diorama.  The next step is to paint the foam with a good, base flat latex ground color suitable for the area of the country you wish to duplicate.  A grayish-tan color works for me.  Then start applying scenery materials.



Here's a couple more N-scale dioramas.  1" pink foam, with some pink foam glued and carved on top of it to represent low hills.  Painted with a cheap, flat latex house paint for ground color.  Then start applying various shades of ground foam, rock outcroppings, bushes, trees, and other stuff as desired.  Pretty easy, really.

You can do this directly on your layout, or make dioramas off the layout and set them in place.  Works good either way.  Note: a shop vac is your best friend when carving and sanding foam.

Hope this helps a little. 


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My observation with foam scenery ( as opposed to hard shell) is that modelers rarely remove enough foam and the end result looks layered like, well, foam. I can see by your deep tiers already that it is going to be difficult to get smooth transitions. I would have used 2" foam and made all the layers go to the water's edge and cut back from there. Whatever you do, use plenty of joint compound to hide the seams. On my layout, I actually used cloth over the foam.

In my opinion, OP is doing exactly the right thing. Unless you are trying to reproduce specific materials such as cut stone, etc, I think it is a waste of effort trying to carve precise, seamless contours in pink foam. It is best used in 1/2" sheets to establish rough contours. Then, cover the whole thing with other materials as I described above.  The N-gauge dioramas are beautiful, but I disagree that scale doesn't matter. N gauge requires careful sculpting of every detail. Pink foam is great for this. In O gauge, I find that you are better off building up the terrain details additively rather than subtractive carving in most cases. I do LOTS of carving of pink foam, but it is usually to simulate stone, brick or concrete, where the details are important.

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thanks for the continued tips....just added great stuff to one side....since it is the first run at it...thought I would let it dry before doing the other side to see what adjustments need to be made.  I guess I will just use plaster cloth over it and paint?   comments welcomed.

thinking i might should have smoothed it some....maybe just smooth some out with knife or hot wire.....




@Gilly@N&W posted:

Great Stuff shrinks. Make sure to give it plenty of time to set up.

Some of the Fort Pitt modular display is foam build-up.  Over time, heat, storage, etc.  does effect the foam.   Modules have shrunk, and in some cases warped.  Rebuilds/repair usually involved some type of wood base and attachment with foam safe construction adhesive.  Encapsulate the foam with plaster/plaster of paris, drywall compound, or some of the plaster cloth products available.    


Last edited by Mike CT

Personally I like foam. I try to use the thickest sheets I can for the project. Mountains I use 2" thick. For flatter areas like you are doing the 1" works best. I shape my foam with Hot Wire Foam Factory carving tools, Fusion Fiber (would work really good for your bridges scene), latex interior paint and the texture from Scenic Express. I do most of my carving, painting and initial texture outside, then install and finish.

I really don't like the mess of plastering, painting or gluing.  I use spray contact glue to stack my pieces of  foam together.  To help keep the foam sheets from separating, only use very flat pieces and cut off the edges that are warped from the manufacturing processing, Glue will not hold two warped pieces of foam together. Construction glue can not be carved or cut with hot wire tools, white glue will never set up between sheets of foam.





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Glue will not hold two warped pieces of foam together. 

But  GREAT STUFF will!  It will even fill the gaps. The new cans of GS have on(GREEN) /off (RED) nozzle control so you dont need to clean or remove the tube anymore. . . sort-of-works!

Once the GS has dried, the next step is to shape it a bit with a small saw or I use a Dremel with a large cutting disk.. Once shaped ( dont be concerned with detailing the foam) then apply lightweight joint compound over the foam with a small putty knife; again shape it a bit;. then WHILE the compound is WET rattle can spray on your colors like earth tones or a nice green ( Spray in across in bands to show geo-layers often found in cut-away rock) ; while the paint is wet apply ground covers grass and earth. Use a Dust Off spray to force the grass into hard to reach spaces. Wait a day or two then using spray glue from Woodland Scenics apply more grass and trees or whatever and let dry.

I after-spray with either silver, nickel, copper or gold metallic spray paint to get a "slight" reflective quality to the mountain work. Or for a darker feel,  lightly spray with black.

You can do large spaces this way. Be sure to tape and cover all tracks and background walls before doing anything. And remove the tape before running trains on that track!!.

Low temperature hot glue is actually a good way to do rough assembly of foam. Holds well and makes for fast work. 

Another trick is to purposely use foam-incompatible spray paint over foam when you want an aged, weathered look. It softens the edges and corners and makes it look like it has been out in the elements for years. I often do "old" concrete that way.  Just don't overdo it.

I've used Great Stuff to form several mountains / hills.  Take a look at CJ Ambrosi's YouTube videos.  Process is:

  1. Determine locations of scrap or carved foam blocks for the general shape of the hill.  Position them.
  2. Take some low-loft quilt batting (available at almost any craft store) and layout it out to cover your hillside.  Mark and trim excess to slightly more than needed.  Leave some for folds.
  3. Pull the batting away and spray the GS over the foam.  Start from the bottom and work up.  
  4. Put down the batting (from the bottom up) and press it onto the GS.  Make sure it adheres and be sure you are wearing gloves.
  5. Continue until you have reached the top of the hill.  You can trim it more exactly after it dries.
  6. Paint with latex paint (you'll be dabbing it into the batting).  Apply ground foam, trees, shrubs, rocks, whatever.



@Avanti posted:

In my opinion, OP is doing exactly the right thing. Unless you are trying to reproduce specific materials such as cut stone, etc, I think it is a waste of effort trying to carve precise, seamless contours in pink foam.  Well, with a little practice, not really.  For that matter, to speed things up, you can get the contours close, then smooth over the seams with some lightweight spackling compound (available just about anywhere that carries home paints).

It is best used in 1/2" sheets to establish rough contours. Then, cover the whole thing with other materials as I described above.  If you want to build a big mountain, three or four 2" thick foam sheets will go a lot faster than a whole bunch of 1/2" thick sheets.

The N-gauge dioramas are beautiful, but I disagree that scale doesn't matter. N gauge requires careful sculpting of every detail.  Huh???  Yeah, well, okay, we'll assume you're correct on both counts.  I've included some more pictures of a couple of O-gauge dioramas that I recently slapped together.  You wouldn't believe how much faster I put these together compared to my N-scale dioramas that I posted earlier.

Pink foam is great for this. In O gauge, I find that you are better off building up the terrain details additively rather than subtractive carving in most cases. I do LOTS of carving of pink foam, but it is usually to simulate stone, brick or concrete, where the details are important.  Good point.  But I wouldn't hesitate to use either method (additively or subtactively), whichever provides the best results (first choice) or faster results (second choice, if no difference in results quality).





Here's a few pic's of some O-gauge dioramas I put together recently.  They are merely some 1" thick foam bases with some more 1" thick foam pieces glued to the tops to provide a little variation to the ground contours.  The sky boards are some scrap corrugated cardboard pieces painted a sky blue color.  Unlike the N-scale dioramas I posted earlier, these went together much faster since I didn't have to worry about fineness of detail that N-scale requires.   

I use DAP clear caulk or LocTite Power Grab caulk for gluing foam pieces together.  Apply the glue in a zig-zag pattern, then press the pieces together and weight down if necessary to dry.  Usually overnight does it.  Note: do NOT apply a big circle of glue around your zig-zag pattern of glue.  Polystyrene sheets are water-proof.  The outside circle of glue will dry, and whatever glue is left inside the circle will remain wet forever, as it is no different than being back inside the tube again.

I tend to use cheap, long butcher knives and steak knives (from dollar stores) and cheap, retractable, box-cutter utility knives for slicing and cutting foam pieces in the rough shaping process.  With a little care and some careful work , you can actually get precise, seamless transitions if so desired.  Or, you can merely get the seams close and use lightweight spackling compound to smooth over and hide the seams.

I also make use of Surform rasps and coarse foam sanding blocks for shaping the foam.  This generally works best for a smoother ground surface, where one might be trying to form dirt-style hills or ditches or other land forms instead of rock outcroppings.  This is where you REALLY need a good shop-vac for clean-up.  Yeah, it's messy, but you only make the mess once in any particular area.  There's been a lot of information posted on carving rock and stone out of foam, so I won't go into that here.

Once I get the foam shaped to my liking, I paint it with a flat, latex house paint in a suitable ground color.  Interior or exterior paint, doesn't matter.  Often times you can find mistints for sale wherever they mix paints, for a considerable savings in money.  Most of my model railroading ground paints over the years were purchased thus.

After the ground painting, you can really go to work with various colors and shades of ground foams, rocks, pebbles, natural and artificial weeds, turfs, dirt, debris, stones, pebbles, rocks, trees, shrubs, etc. etc.  This portion goes REALLY fast, just sprinkle a little bit of this and a little bit of that, until you achieve the look you're after.  Secure it all down with home-made or purchased "scenery" cement (i.e., watered-down glue).  You can put in roads (paved and or gravel), parking lots, buildings, track, ballast, whatever you want, really at anytime during the building process.

Well, this pretty much sums up my methods of scenery building,  There really is no right or wrong way to do scenery.  Just whatever works best for you and whatever produces the most pleasing effects.

Hope this helps a little more yet. 



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Well the great stuff did great damage......I used liquid nail to glue down the foam to each other....looks like the great stuff penetrated the first and second layer on the front side went underneath and broke the seal.  I guess I did a better glue job between sheets 2 and 3 but then again #4 was lifted as well.

I watched the Ambrosi you tube video - but maybe the difference is he didn't have layers of foam but blocks of foam.....not sure there is an easy fixe here - but maybe to start over








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Last edited by msp

Okay i fixed my problem and did the other side...put in a couple of rocks...

I am going to shave it down some...flatten some of the slope then I can

If I understan AlanRail above I can then fill in gaps with joint compound and the paint.  I think that is the approach I have decided to need for plaster cloth at this point....

we will see what happens.





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Last edited by msp

A little different, 20+ years ago.   Wads of newspaper and plaster cloth added the detail.  Interior tunnel mold, Woodlands Scenic, adapted from HO to O.  

Rock molds are Woodlands Scenic.  Three different molds were used, with joint compound and plaster of paris.  Rocks were secured with construction adhesive.  

Last edited by Mike CT

Okay here is the latest...I have put plaster of paris over my great stuff and foam.   Hope that is not a chemistry experiment gone bad  

See attached questions.


1.  What is difference between plaster of paris and sculptamold?  I used PP because that is what I had.

2.  Do i need to apply the PP to the riverbed or will the WS water go straight on my MDF board base?

3.  My plan is to do the first coat of paint or so on the bench then move the 2X2 piece to the train table.  From there i will do the final detailing in place.  I think I can envision it better there also.....I plan to make this like a puzzle so I will not finish the edges and put my next piece (built primarily on the bench) put it on the table then do the edges of both pieces once on the table for conformity.   Does that make sense?

So with what you see I think next is to sand a bit then paint.    Does anyone have "go to" colors for the river?

Thanks again, and I am open to any comments or suggestions...






You need to seal the gaps and edges of the terrain/mountains on each side where they meet the riverbed so that, when you do the water pour, the product will not escape or bleed under the terrain, but stay in the riverbed. Not sure how you are incorporating the scene into your layout, but you probably also need to seal the ends of the riverbed as well so the water pour doesn't run out the ends.

There are a number of ways you can do that sealing along the edges - paintable caulking, sealant, flexible joint compound, etc. 

Not sure if the base wood you are using is waterproof but, assuming it is not, you also need to seal it. I use a latex paint on the riverbed which seals it all along the flat part and up to where you have sealed the river edges and, at the same time, provides the color I want for my riverbed. Dark greens, browns and blues are typically used for riverbed colors, but the choice is yours, and multiple colors can be blended from the edges to the center. Some water effects can also be tinted before pouring which may also effect how you paint the riverbed.

Don't forget to glue into the riverbed some rocks, stones, tree branches and whatever else you think looks good before your water pour.


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