Feb 23, 2018
What is the best for top coating on scenery plaster cloth, plaster or drywall mud, or?
Since the plaster cloth dries with a rough and porous texture a thin coat of drywall compound or plaster will work fine. Advantage with plaster is you can thin it out to a wash and brush it on and it dries faster.
Plaster cloth with its rough texture makes a fine base for applying scenic material, such as grass, directly on it with a glue like Elmer's white Glue-all. I wet the surface and then apply the glue directly to the plaster cloth, then scenic material, then follow up with a few drops of diluted Elmer's. Scenic material can simply be removed by wetting it to do some work.
Last three modules I've done have been two-layer; plaster-soaked paper towels (cut up usually to about 1x2" in size) over various supports (hard shell, cardboard web, foam) with a second coat of patching plaster brushed on before first was entirely set. It's available in small quantities, and the 'glue base' stuff seems better than just patching material. My support layer usually has a final layer of newspaper taped on top to keep it smooth, and I may or may not tear loose the supports after everything is done.
Patching plaster seems to deal well with the differences between previously-done areas and new. If you have areas to build heavier, fill, or profile, another coat brushes on fairly well.
I also mist it lightly to make sure it gets fully hardened & set, don't mess with it until it starts to warm up to room temperature again.
I then paint everything with a brown latex paint, which seals the surface and keeps it from chipping as well. I'll do standard ground foam, dirt, leaves, whatever, over top of that.
The disadvantage is that it's heavy, but it can be carved and precisely controlled, and never looks like foam layers. And I also have to have a 'lot' of removable scenery to access the inside of modules, these plaster methods work well with lift-off sections. This is the semifinished Ross Run module. The dowels sticking up are actually lift-up handles that will be in the trees.
Like most things, you do what you are comfortable with, and I've evolved this hard-shell stuff over about 45 years of modeling. The biggest 'oh, CRAP' with this method is if you have 'stale' plaster that doesn't set up rock-hard (was allowed to get damp in the package), I usually to a little test mix in a paper cup first and let it set up to make sure my plaster is still good before I make a commitment for a permanent piece of scenery.
If you've been at Altoona you've seen me plugging away on building the support web on this one, I've done a 'live scenery build' on this the last couple years.
I have been using drywall mud applying it with a putty knife then smoothing it out with an old wet paint brush.
I use extruded polystyrene foam insulating boards (come in pink or blue, NOT the white expanded foam board). Cut and sanded to shape with any seams or gaps covered in light weight spackling compound. You end up with a very light but still very firm base for scenery.
I am presently using Molding Plaster by USG, National Gypsum even manufactures it. It does come in a 50# bag. You have to purchase it from a Drywall supply company. You can either apply it thick to create Mountains and rock cuts or wet to seal plaster cloth. Complete hardiness of the Material (to carve rock cuts or faces) is 24 hours. I fell it is better than Hydrocal.
Is hydrocal plaster? I use it instead of drywall mud. Similarly, bought a 50# bag, not too expensive. I think it sets quite a bit harder than drywall mud, so more resistant to scratches or damage.
I have used Hydrocal for many long years. Drywall mud may indeed work. When I have done room finishing, in a couple of houses once owned, I found that mud did not like to be applied very thickly. So building up a surface, if too thick tended to have cracks when drying. Much more so than Hydrocal. But, if mud works for you, by all means go that route. As it is inexpensive and more readily available in large quantity than Hydrocal.
Scenic express gypsolite works like plaster, but has a gritty texture. When painted it looks more like rough ground. You can't cast rocks with it, but I like the look for ground base. It can be mixed in different consistencies depending on how you need it, ie brushing, or whatever. Also when using plaster cloth you can smooth it by rubbing the plaster around with wet fingers for a smoother finish.
That's it, that's all I know... oh wait, fig newtons are named after the town, not the scientist.
These are all well known techniques/materials (although, except for the extruded polystyrene foam board, pretty dated) ...but one major material hasn't been mentioned yet, which I find pretty strange, because, over the course of 25+ years, it has proven to be one of the easiest to use, most forgiving, and gives superior results...Sculptamold.
Sculptamold is part lighweight hydrocal, and part cellulose product (paper mache), combining the best of both...it is easy to mix and use, plus has the MAJOR benefit of being able to be precolored (with acrylic or latex paints)...this is beneficial, especially for modules where the scenery forms may be chipped-with plaster or hydrocal, chipping will expose the white product underneath; by precoloring, and chips will only reveal the same color material beneath.
Sculptamold can be applied on any type of scenery form, and can be mixed thinner, or thicker...when dry, it can also be sanded and carved.
I use just bare form (can be sanded and carved to a high level of detail), or foam with a Sculptamold layer.
For this NTRAK module, I created low rises with shaped foam, covered with precolored Sculptamold, then carved shaped the erosion lines in the exposed cut...
For this NTRAK module, I built the entire mesa from foam, then, again, covered the entire form with precolored Sculptamold before carving detail...
For this T-TRAK module, I built the forms from foam, covered only the slopes with precolored Sculptamold, and carved the upper strata into the bare foam.
and on this T-TRAK module, there is no Sculptamold whatsoever...rock strata was cut into the bare foam, then painted, before ground scenery was added...
But beware, Hydrocal and drywall mud are two entirely different things. Hydrocal is plaster, it sets and gets hard quickly, and has a surprising amount of strength. Drywall mud is something that never sets, takes forever to dry and can't be put on in any amount without problems. And a bit of moisture, like when doing scenery, it's soft all over again. I know there are folks that use drywall mud and get away with it, but why take chances.
Have no experience with molding plaster, but I can see where it would have advantages, my next layout will be that or hydrocal.
I tried dry wall mud, so far I'm liking it. I thined it down a little so I can paint it on.
Drywall "mud" works fine and is what I have used for along time over foam. I buy 25lb bags of the 25 minute set and mix it myself to get the consistency I want as opposed to the pre made stuff, that can work out a little more expensive. Either way, I've not had a problem with it in 5 years that I have used it. The "mix it yourself" stuff goes a lot further as well.
I buy 25lb bags of the 25 minute set and mix it myself to get the consistency I want as opposed to the pre made stuff,
There's an idea. That's "setting mud" which is for all purposes the same as plaster. It is important because the usual kind, premixed or not, could bring big problems when doing scenery or ballasting track because it will redisolve with water.It concerns me that some will see the statement that drywall mud works fine for me and go get the other kind,
Your so right, my mistake. This "mix it yourself stuff" (can't think of the name of the top of my head, but is bought from Lowes) has tolerated water and alcohol when ballasting my track very well. I can't recall having any problems with it.
Have to agree with Bruce. Started using Sculptamold more years ago than I care to admit. Its light weight, paint and glue acceptance made it my first choice.
Ughh! When will these archaic paradigms die... never seen any part of the earth that looks like latex brown paint.
Doesnt chip? Wannabet?
I could paint it hot pink and have the same results, because by the time I'm done, none of it ever shows anyway. I pretty much dip all my support wood, roadbed, everything in it more as a sealer. It's never a final color. But it's really important when you're adding layer after layer of water-soluble material on top of things - dirt, ground foam, ballast.... to do something to seal the plaster coats. Pick any color you want, just don't leave it white.
Here's an overhead of that same module showing the 'in process' layering on top of that brown latex:
The dirt is....sifted dirt.
Did this back about 1990, still not chipping and that entire section behind the train is removable as a lift-out.
Did this one back in 1976,....hmmm..... still not chipping.....
If I do miss a final scenery spot somewhere, it's nice that it's under there - brown instead of white. And at least on patching plaster, it soaks into it to the point where it really does make a difference. I'm not saying chip-proof, I'm just saying that you need to do something, either tint or paint, underneath any final texturing, if you're using plaster. Paint helps, three layers of glue, foam, and dirt really forms a shell.
I hadn't done any hard shell for decades until I did the T-trak modules last year, then went back and did the Ross Run logging module after I got my mojo back. It's still one of those things like working in watercolor, pencils, or oil, you get a feel for the media and kind of stick with it if you like the results. The only catastrophe I've ever had with plaster products was using stale stuff that never really set properly to a hard result.
I can't imagine using standard drywall mud, between solubility, shrink and cracking.
Always wanted to try sculptamold, but my areas to do have been so small in comparison to most that it seemed unnecessary. Lot more tempting if I was doing major square footage.
I do a similar thing. Give my white plaster a coat of color, a brown, to help seal it before applying anything else. Once ground cover etc is added, the initial color is not seen or blends in with everything.
Don't avoid sculptamold. For large expanses of scenery it will be more expensive and a bit troublesome to use, but both David Haines and I used it for things like rock faces.
The good and the bad with sculptamold is that it takes a really long time to dry. That's good when you are doing carved rock faces because it remains workable a lot longer than plaster, and responds to carving and different tools in different ways as it dries. But for covering large areas, what a painit would be. We found that it often took more than a week to completely dry and set! And it must be completely dry and fully set before you can paint it.