Yesterday, the pink stuff was glued down on my new layout and today I affixed the fascia. I’d like recommendations for a product to fill the cracks between foam pieces, and to fill the gaps between the foam and the fascia. I went through my scenery materials box to see what I had on hand and here is what I found:
Woodland Scenics Foam Paste
Red Devil OneTime Spackle (I am concerned about this stuff cracking as I work on the layout)
A product called FoamPrep purchased a number of years ago - it was advertised as a sealant for the bead type of foam
Acrylic silicone caulk (paintable, clear)
On a related question: what can I use to seal the foam? I intend to use triangular pieces of foam to kind of radius the backdrop corner. I hope there is something that will seal the surface of the foam so I can paint it the same color as the backdrop.
I used white marker board material for the backdrop. Light, easy to cut and cheap; and it fit nicely into the plastic track material I am using. For various reasons, I installed the backdrop with squared corners.
Rather than rigid foam, I am a fan of expanding foam (i.e. “Great Stuff” that comes in a can with a long nozzle). I don’t use the foam itself as finished scenery, but rather I cover it with a “soil” layer of home-brewed plaster. Actually, it’s more like papier-mache, blended with joint compound and other color and texture agents. It’s all water-based and can be applied nice and thick, such that it fills gaps on its own. In fact, I rely on the gap-filling to get it to lock into the lumpy expanding foam, as there is no natural adhesion between my soil plaster and the sheer skin of the foam.
So I guess I have two recommendations here: try expanding foam (perhaps the low-expansion variety sold for sealing windows), and consider using a finish plaster coat over everything.
To see more about my technique, check out this article on my web page:
Now there’s a great idea, seeing as I will have a bit over a 2 inch gap from the edge of my pink foam to the fascia. I think I will put in a bit of a tape webbing or something similar, I don’t want to fill up the entire space behind the fascia all the way to the bottom with expanding foam. Or have it just run down to the floor.
For the gaps in the foam between modules, it depends on how big it is. The smaller ones, I just put scraps of foam in the gapwith some caulk to hold it in. At right angle joints the gap is wider because of the 1x4 side boards, for those I put a scrape of 1x lumber in the gap with caulk to hold it.
Agree with WP&P on filling the gaps. I think I’d favor the low expansion spray foam if you want a seemless look, as it is easily cut and sanded.
As for painting the foam, paint it, there is no need to prime it. Think I’d use the color full strength, but if you want, you could experiment with some dilution. Some folks seem to have good luck with diluted latex paint.
Scott, on small gaps where the foam edges would not quit seal, I have had luck with straight Elmer’s white glue. While the glue was wet I sprinkled on the ground foam.
I agree. I think a very good way is to use gap insulation expansion foam like SikaBoom or others. I used that one once and it is a great product and easy to shape.
BE CAREFULL with expanding foam, it can be a REAL MESS to work with, and a disaster if you do it wrong or use too much, make sure you use “minimal expanding” foam and realize even that expands ALOT. If you get any on your fingers or clothes IT DOES NOT COME OFF, so fair warning, experiment first BEFORE you do any final applications. At small cracks I am a big fan of adhesive caulk, if you are doing zip texturing over the foam, if you are plastering over the foam, then sealing all the cracks really isnt necessary as the plaster cloth will cover everything.
I use Great Stuff expanding foam, you can often find on sale at Lowes and HD. Wear gloves when using it and tape off any area you don’t want it to go. Give it at least 2 to 3 days for it to fully expand and cure before carving it as it will shrink where you carve it if you don’t wait. Seal the carved are with a soupy plaster mix.
I guess I’m too old school. I just completed a project for just that purpose. I had relatively small gaps between my scenery and fascia (1/8-1/4"). I mixed a thick paste of plaster of paris. I can work it in nice and flush with a 1" putty knife. Once it’s set up, I apply scenery to it just like any other part of the layout; paint, white glue, sand, ground foam and, now, static grass. I photographed it in steps, but haven’t uploaded them yet. Have to take wife to doctor this morning. I’ll post them when I get back. Hasta la vista, baby!