Foam over plywood isn’t going to be a practical option for me in doing the scenery on my layout, so I was wondering a few things about plaster of paris.
How thick can it be applied without any sort of form underneath to make small hills, culverts, ditches, etc?
Is the best (most practical) method for making mountains with plaster of paris using plaster dipped shop towels over wire mesh?
Hydrocal isnt’ readily available in large quantities in my area, but plaster of paris is, and is also much cheaper. Is there another alternative to plaster of paris (that can be found at home improvement centers) that would work better as a basis for scenery?
How long does plaster cast hills and mountains usually last without crumbling or causing future problems with the scenery?
Weight isn’t an issue with my layout, but I was wondering… does 20lbs of dry powdered plaster equal 20 lbs of set up plaster after it’s applied to the layout?
Plaster does not stick well to plywood. For mountains and hills use screen door wire mesh (plastic or metal). On flat surfaces staple wire over the area to give the plaster something to bite to. If the area is small just use staples but leave them stick up about 1/16 to 1/8 inch.
Is there a reason for not using foam. You don’t need to cover the plywood completely. Contoured layers of foam, or chunks of foam to support screening or cardboard strips are all various methods that are generally used for scenery. If you feel that the plaster won’t have enough bite to the ply, staple some wire screening down then run it over supports for the shape you want. Plastercloth or plaster/ hydrocal soaked paper towels can be laid over it. A product that bonds well to plywood besides the floor leveler is USG Durabond, sticks to ply very good but the only drawback is it sets up to unworkable in 10-15 minutes.
Bob K.
I cannot comprehend this obsession with foam. It first showed up in a September 1959 Model Railroader. I had a chance to use the blue foam back in the mid-70’s and saw no advantage it’s use in a permanent layout. The cardboard lattice covered with plaster towels sure costs less. At $28 a sheet I can think of better investments than foam sheets for scenery. The argument that it easier to make below track level terrain with the foam is highly overrated. Just cut a section out of the plywood and frame like this:
That was all done with cardboard lattice and plastered towels, with less mess than cleaning foam “boogers” off everything. The river is below the plywood.
I’m with you on that point Harold, (at the risk of getting chased into my corner) esp. on the pricing front, I cannot see how foam can be more ‘application flexible’ than contouring your own base with either cardboard lattice or wire mesh/poultry fencing, (although I have no practical experience of foam to base this on).
Sure, I can see ‘some’ advantages in certain situations or layout locales, but to do an entire layout this way sitting on 2" of foam to me seems a waste of resource/time/effort/$, its just a preference thing I guess but thats my [2c].
An open grid bench work with a fixed roadbed surely gives you more options for sub-roadlevel modeling rather than having to sit the entire roadbed on 2" of foam just so you can excavate in one or two specific areas [%-)] , and if you do take this route you can only go down as deep (or almost as deep) as the layer of foam you are modeling on anyway, before you need to add more terrain under the foambed, which kind of for me defeats the purpose of using foam for the ability of lower scenery.
I’m going to try it on a section of my new layout to see what its all about, but I sure wont be laying it all over the place and then covering it up anyway making it obsolete.
Like I said, it’s a preference thing, no right or wrong, just diff of opinion.
jshrade, I have limited experience; one modest layout, and I did use the foam. I enjoyed its use, but I can certainly see the benefits of other methods, not the least of which is a substantial reduction in costs. The photos regularly posted by these other two gentlemen speak for themselves.
Plaster, especially if painted, and if left undisturbed, should last a very long time…years.
However, it will have to be shaped and supported, or reinforced, with an eye to helping it to last. So, I would use metallic screen with apertures anywhere from 1/8" to 1". So, window screen to chicken wire. Over that, at least two layers, overlapped, of plaster cloth of the type you describe. When that has cured, you can then affix thin molded plaster rocks, more plaster, or sculptamold, or what have you.
Remember that many use cardboard strips, either stapled or hot glued, to form their sub-structures. Some even use crumpled newsprint. So, you have options, and may wi***o try your hand at several test sections to see which works best for you.
As on of the forum’s foam layout advocates, I’ll chime in on why many of us feel that foam is a superior layout construction medium than plaster & it’s associated framework.
First of all, is foam perfect for every application? Nope. If you’re building a spaghetti bowl, handlaying track, or running #1 gauge steel live steam, you’ll need to use wood.
On to individual points:
Absolutely not true. Foam is the ENTIRE layout base, from the subroadbed to the “add flocking” layer. If you buy all the materials required to built a traditional layout from that level, your costs are between 2 to 3 times that per square foot, as compared to a sheet of foam. With foam, you have to buy the sheet of foam. With traditional construction, you have to buy the foundation subroadbed lumber, upright support lumber, roadbed lumber, screws, cardboard, screen wire, newspaper and plaster.
a 2" thick piece of 4’x8’ pink foam cost $19.50, as of last Friday. A 4x8 sheet of 3/4" BC plywood cost $32.98. YOu can use ALL of the foam when constructing a layout, but you’ve got a LOT of scrap plywood if you’re cutting out cookie-cutter subroadbed.
OK Harold, I’ll bite. Who are the guys on top of the freight cars, and what are they doing?
I’m an open grid fan, too. I don’t mind the woodwork and I’m in no ru**o get to the finished state. The science of all this ends about the time the plan is complete (which, of course, it never is) and then the art takes over. After I lay subroadbed, I take some time to look at it, complete with the track lines. It might stay that way for weeks. Sometimes I get a better idea and a section gets redone. Pretty painless (and cheap) to do before the roadbed and track is laid. Then I do the same thing with the roadbed down. Then again with track laid. I sort of enjoy the construction process. I have a 40 x 14 N-scale layout underway, and it’s amazing the amount of subroadbed I can get from a sheet of plywood. Weight is not a consideration, the layout is not going to be moved.
In the end, it is the final product that matters. Whether somebody uses open-grid, a door, a solid table, foam or their backyard makes very little difference. As long as they enjoy it and it makes them happy, that’s what this is all about.
Unless my lovely wife, who seems to want to pack up our things and move every few years, builds up a head of steam in that direction that I can not bleed off. If so, the railroad won’t be moved, but disassembled into its components and those reassembled later in some other form.[:(!][banghead][banghead]
What are legs? My layout’s attached to the walls with shelf brackets.
If you MUST have legs, 2x2 legs, attached to 1x2 L girders glued & screwed to the foam are all you really “need”. But even if you decide to add a full sheet of 1/4" plywood under the foam, it’s still a lot faster & cheaper than building L girders & plywood roadbed.
My railroad depicts the 1870’s so I take pictures that look like the 1870’s photos. The photos from the period always had the train stopped and everyone got out and posed on the train. They are the brakeman. When I was doing On30 and the equipment was 1920’s I tried to duplicate that photo style.
I just think the “blue foam” movement is over cooked. My 4x8 test railroad uses 9/16 OSB for the top and backboard. It duplicates the $28 a sheet foam for only about $12.
The foam has no structure to attach un-wobbly legs. If you build such a structure you might as well have built with wood. A directional lighting system such as my 4x8 has cannot be attached to a foam layout cheaply. I detail my 4x8 at:
The Great Foam Controversey, part ???
I like to use this stuff, under vinyl siding and insulating foundations. Oh, every so often it works great to sculpt my scenery on the layout. But to have the trains running on foam instead of spline, not ready for that, and no one can convince me of it’s structural integrity, to only glue the railroad together. Must be my old school thoughts and 30 years as a finish carpenter/ builder.
On the other hand, for light weight, portablitity, speed of construction, and costs etc. foam should work .
Just my thoughts.
Bob K.
Well, my 8’ X 11’ ‘two-by-four’ and plywood monster, heavy though it is, has 1" extruded foam glued directly to the 5/8" plywood. I have no way of confirming that the 2" foam suffices as its own table top, but surely Ray knows of what he speaks…he’s running trains just fine that way, and he isn’t the only one on this forum.
My arrangement is rock solid, although diagonal two-by-four braces helped hugely. I will admit that the foam is not rugged in that you can’t clamber up on it without some form of load-spreading item, like pieces of plywood. I learned that right quick. For those smart enough to make shelf-type layouts where they don’t have to climb up on them, I’ll bet that even the 2" foam, by itself, is overkill. And, the 2" stuff sure makes adding layers for sculpting topography a breeze. Literally minutes…once the glue is set.
All this said, I admire the work, and respect the perspective of both of you gentlemen. To each his own.
I too, was reluctant to try foam, until I got some, glued it down and started carving. In a sentence, “IT’S GREAT!!” (Apologies to Tony the Tiger). You don’t really even have to cover it with plaster. I use a hand wire brush and shape it, a screwdriver to create erosing effects. I paint it an earth color, sprinkle ground foam on while the paint is wet. If you’d like to see some examples, check the January - March(?) 2005 issues of Model Railroader for Pelle Soeborg’s series. My layout is a combination of plywood subroadbed and foam. I happened to go by a construction site and they were throwing away huge pieces of foam in the dumpster. They told me to “help myself”… I wished I’d had a bigger truck that day. I just layer it, carve it, paint it, sprinkle ground foam on it, and voila! If you live in an area where there’s construction going on, stop by and talk to the foreman. They’re usually going to have scraps that are more than big enough for you to use. If nothing else, give it a try, you may like it.
Well I didn’t exactly intend to start a ‘foam vs plaster’ war, or a symposium on ‘which is better, open grid, or foam on supports’…
Fact of the matter is, foam is not an option for me, because quite frankly youI can’t fit a 4x8 sheet of foam in the back of a Jeep Wrangler, and I don’t have any other means of getting sheet foamto my house. Not to mention it’s nearly impossible to find 2" foam here in the south (most building supply places down here only carry 1/2 and 3/4 inch at best). I built my plywood on L-girder benchwork while I had a pickup truck, so hauling the 4x8 sheets of plywood wasn’t a problem then, but that was several months ago, and I’m ready to start working on scenery, which is why plaster has come to mind.
As far as cost, I didn’t expect this to be a cheap hobby, just a long-lived one, and one I could enjoy for many years, so I only asked about plaster to find out what’s been tried with success and what options are available.
My plans are to model the piedmont region of Georgia, which consists of mildly rolling hills, distinctive of where I live now. I’ll only have one ‘mountain’ which will only be about a 2x4 section of the layout, and it won’t be very big anyway. I’ll have four distinct regions on my layout, city and railyard, coal mine and mountain, small town branchline, and rural Georgia whistlestop. The city area will be mostly flat anyway, the coal mine and mountain will only display the lower portion of the mountain and associated foothills, the branchline will be modeled after my local town, which has very gentle hill, and rural Georgia will be primarily flat farmland and fields. Most of my scenic contours will come up from the benchwork, instead of down. The few areas that will be lower than the rest of the layout, I can easily cut out of the plywood base with a jigsaw.
I got into this hobby expecting it to take at least a year just to get the basics up and running, and at least another 4 years before all the scenery
On my previous layout, which was open grid with plywood/Homasote-like roadbed, I too used Plaster of Paris because of cost and the difficulty in finding Hydrocal. To me the simplest method to span the fairly large areas without any track - it was a harbor layout - and support the plaster, was to use fiberglass window screen material. It’s cheap, doesn’t cause mysterious electrical shorts, doesn’t tear your hands forming it, and staples to the plywood sub-roadbed quickly and easily with a staple gun. I then used the reinforced kitchen paper towels (Bounty?) to dip in the plaster mix instead of the brown paper towels recommended in the MR articles. The window screen was good at preventing the plaster from going on to the carpet below - only the very runniest mix got through! The resulting scenery base survived multiple trips in moving vans without chipping or cracking.
The screen and reinforced paper towels solved the plaster of Paris strength problem, and added a very limited amount of flexibility to help resist cracking. For me, installing and forming the screen was much more intuitive then trying to create shapes with cardboard strips (been there, done that). I used scissors to cut the screen, and a staple gun to fasten it. Added cheap wood lath “risers” stapled to benchwork to support screen shape only where needed. Joining 2 pieces of screen was simply jamming the cut edge of the added screen into the mesh of the existing screen, and smoothing the joint with my fingers. If for some reason the joint needed more strength than the edge jam technique provided ( I think I did this once), I would staple through both pieces of screen into a strip of corrugated cardboard.
Did some more thinking last night after posting my response. The 4 primary scenery bases in widespread use that I know of are foam, plaster impregnated gauze, free-standing hard shell Hydrocal; and plaster on screen. Each method tends to produce different types of terrain naturally, and it takes a lot more effort to get a different type of terrain from a given method.
The foam lends itself very well to shallow shelf layouts where the proportion of track and structures is relatively high when compared to other layout styles. Foam naturally produces flat and/or smooth terrain that is well-suited for mounting structures on. It also can produce your relatively smooth rolling hills without a lot of effort. Producing craggy Western mountains with numerous gullies and other rough terrain takes a lot of extra time and effort with foam. At the Home Depot where I bought my foam, it only came in 2 ft x 8 ft pieces, and 1.5 in thickness. You can easily cut or snap the pieces to smaller size for transport, since you will rarely use a full size piece in filling in scenery.
Hard shell scenery made from plaster soaked towels naturally produces very rough terrain, even when applied over window screen. It takes extra effort to avoid wrinkling the towels to get smooth terrain - and the pressure is on when the plaster sets so quickly! Also, a sturdier underlying form is needed to lay out the paper towels without wrinkles, which is required for smooth terrain. Balled up newspapers and spaced cardboard strips generally aren’t good enough. Placing structures on hard shell requires lots of pre-planning or a good supply of blades (plaster dulls them quickly) for whatever cutting device you are using. Typically for structures installed after the scenery base, a hole is cut and some kind of flat base (usually foam or wood) is inserted into the hole. Placing a structure on top of hard shell is likely going to leave gaps around the foundation unless you are going to simulate bulldozing some earth up to
I agree, Fred. In fact, I have become and advocate of the ‘eclectic’ approach. I like to use at least two methods in combination. You could build up a couple of layers in foam, with the associated and requisite sculpting and modling to vary the terrain, and then build craggier cliffs and hills with wire and plaster over the base foam.
