Scenic design: Possible framework materials for creating "rolling hills."


My hills are created using two things:

1. Extruded foam, and
2. Quick set Plaster (Powder)

I form the basic shape of the hill I want with the foam then give it a coat or two of plaster, using the plaster to create definition etc. Basically I cut out the shape of the base of the hill then cut similar shaped pieces of foam (slightly smaller than the last) and lay them on top of each other until I have the height I want. Once I have the basic shape, I cover it all with plaster to form the final shape, be it a smooth rolling hill, craggy hills or rock faced cliff. Cheap, quick and works well for me.
 
riogrande said:
You can get about 40% more plaster cloth for the same money if you order Activa brand on Amazon btw!
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Thanks for the tip! I scored a single roll from my orthopedic doctor the other day (they only had one expired roll). Good to know of a budget-priced option available online! I'm slowly warming up to the idea of using plaster-cloth since it seems to be one of the most effective construction methods.
 
riogrande said:
Here are photo's of my progress using that method:
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Holy crap! I've seen that thread before somewhere. Your canyons are amazing! I just bought a five-pound box of Activa plaster-cloth for $16.19 with free one-day Amazon Prime shipping. Hope that's a good price. Again, your layout looks really amazing! Thanks again!
 
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wombat457 said:
I form the basic shape of the hill I want with the foam then give it a coat or two of plaster, using the plaster to create definition etc.
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Thanks, man! I'm getting my Woodland Scenics rock-molds next week, so I'll be giving that a go with some plaster of Paris.
 
Yes, plaster cloth over a cardboard lattice, followed by an overlay of some type of plaster (Plaster of Paris, Hydrocal, etc.) makes great scenery. I also mix powdered tempra paint in with the overlay layer. That way if you chip it, you won't have white showing through. If plaster cloth isn't available, however, heavy paper towels dipped in a slurry of plaster will work, too. I also have used plaster over screen wire on my older layouts. Doesn't go as quickly, as the amount of plaster you can mix up and apply before the stuff gets too hard to work with is limited.
 
Thanks for the tips! I was planning to use aluminum wire-screen as a base, recommend by Michael Rose (an active poster on other MRR forums with an extensive layout). The Activa five-pound box seems a good deal since the similarly priced Woodland Scenics' product weighs only a few ounces. I also just bought some Woodland Scenics' rock-molds and plan to pour plaster of Paris into them. My questions is, how do you attach plaster of Paris molded rock-forms to the hardened plaster-cloth mountains?
 
Dampen the hardened plaster-cloth and the back side of the molds, and apply a thin coating of Plaster of Paris. Then stick the rock moldings on. You may have to hold them there while the "glue" layer hardens.
 
Chevron_GATX said:
Thanks, man! I'm getting my Woodland Scenics rock-molds next week, so I'll be giving that a go with some plaster of Paris.
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Chevron,

If you are going to use rock molds then I would strongly recommend you use "Dental Stone" rather than Plaster of Paris. Dental Stone is a little more expensive but dries "rock hard" and will not break like plaster of paris might. Dental Stone is well worth the money and recommended for use as a casting material. I have used both products and would never go back to plaster of paris for use in any type of mold.

Also, be aware that plaster cloth has very little in the way of plaster in it so you will need to overlap the cloth you lay by 50%, then, once dry, cover that with plaster of paris to get any sort of rigidity and strength. Plaster cloth is a good "template" for your hills, valleys etc but don't rely on it for an end result unless you want to layer the cloth 5 or 6 times to get the strength from it. That becomes uneconomical though I would think.

I should add that Dental Stone mixes 100% and mixes to the consistency of a thickish cream texture. That is a huge bonus as there is no possibility of getting air bubbles or little bits of paris of plaster that don't mix properly. One other thing I used it for was the formation of roads and footpaths/sidewalks. Because Dental Stone is less porous when dry, it doesn't absorb paint or other moisture like paris of plaster does.
 
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I see there are five types of dental stone. I was looking at getting type III:

Type 1 Dental plaster, impression
Type 2 Dental plaster, model
Type 3 Dental stone, die, model
Type 4 Dental stone, die, high strength, low expansion
Type 5 Dental stone, die, high strength, high expansion

Amazon sells a 25-pound carton of Garreco type III base stone for $36.07 with free Amazon Prime shipping.
 
According to a Hirst Arts youtube video, USG Dental Plaster (no type specified) is only $30 for 100-pound bag. I see from the Hirst Arts site that they recommend a Garreco-supplied dental stone with a compressive strength of 18,000PSI. That would be type IV. Type III is only as strong as Hydrocal, about 8,500PSI.

I later found that several companies recommended on the Hirst Arts site sell a product called Merlin's Magic, which is a Garreco product, and drop-ships from Arkansas. It's only $30.99 for a 25-pound box or $44.99 for a 50-pound box, but the shipping is expensive since it's heavy and comes from Arkansas. It comes in white, buff (yellowish), gray, and dark gray under the Merlin's Magic brand. This particular product has a compressive strength of 12,500 PSI, setting expansion of .08%, and setting time of 9 to 11 minutes.
 
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Chevron,

I use the Merlin's Magic Dental Stone. I bought a 25lb bag/box of it and with everything I have used it for, still have 3/4 of a box left. I can't say abut the other makes but the company that makes the molds I use for stone walls etc highly recommended the Merlin's Magic to me. I'll take a look at the site and let you know which type I bought.

"...This particular product has a compression strength of 12,500 PSI, setting expansion of .08%, and setting time of 9 to 11 minutes....
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This sounds like what I bought, but I'll double check. I know the setting time wasn't all that long and a heck of a lot quicker than paris of plaster.

Okay, this is what I bought and am very happy with:

http://merlinsmagicplaster.com/product/merlins-magic-plaster-buy-white/
 
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Metro,

Nope, just run them under cold water so they are damp/wet and that's it. Once the mold is dry, "peel" the mold back from the plaster and it will pop out very easily.
 
I purchased 50lbs of hydrocal some time ago and it was very cheap, like $1.00 a pound or less and shipping was about $50 as I recall. It may be more and I'll try to find the information if you are interested. I find that it was the best to work with because it stays green a long time so you can carve the surface if you like.

Dave
 
Thanks, but I found Hydrocal locally for only $44 a bag for a 100-pound bag. Just trying to decide if I should go for wombat's fancy dental labs ton material instead: $30.00 for a 25-carton, plus $30 ground shipping, a week from Arkansas. The neat thing about Merlin's Magic (Garreco dental labstone) is that it comes in different colors.
 
Dental-plaster supplier update:

I found a local dental laboratory supplier in Los Angeles and bought a 25-pound carton of dental-stone plaster for only $22 (plus, they even gave me a discount for picking it up!). I then went to Home Depot and got several colors of Quikrete liquid concrete colorant to make my own color-all-the-way-through molds, and they worked out great. The dental supplier I found carries a number of dental lab-stone and dental die-stone plasters in-house. Here's a PDF of their catalog: Star Dental Supply.
 
Unfortunately, Star Dental no longer carries Zhermack products. Here's a premium dental-stone sold by the only supplier I could find: Zhermack Elite Rock type IV. Type IV is very strong (18,000PSI). The unique thing about this dental plaster is that it comes in a silver-gray, whereas most of the other type IV plasters sold at Star Dental come in "dentist" colors, either pink, blue, or green. They apparently make two versions: regular-setting (14-minutes), and fast-setting (10-minutes).
 
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