Hello everyone,
I’m working on a friend’s layout and we are in the process of building mountains. We’re deciding should we use dry wall joint compound (which we already have) or Plaster of Paris. Which material is preferred? We are you open to any suggests. Thanks in advance!!!
I used dry wall plaster over metal screen on a layout once. If I kept it thin, lest than 1/4" thick it did not crack to bad but I had some large cracks to fill any way. I also found that it cracked a once in a while for about 2 mo. I just covered the cracks with ground cover.
It was not able to take much stress with out damage.
I do not use it for mountains any more and prefer plaster soaked paper towels for mountains now. I still use joint compound to fasten and blend in rock castings, if it cracks it looks natural.
I have used compound to make streets and side walks and it has worked well. I still prefer plastic for streets but have used compound to fill gaps.
One thing to evaluate is the amount of shrinkage and then cracking that may occur later, if there is any. Woodland Scenics has a lighter compund that they claim won’t crack or shrink. If it is like that, then maybe it will hold up. I have been experimenting with all types of “mountian making” techniques. I’ll share them.
this includes:
Cardboard webbing with industrial paper towels dipped in think mix of starch.
Cardboard webbing with contractors red resin paper, painted with starch.
Cardboard webbing with plaster soaked paper towels.
All of these give the same base results. Starch is probably the cheapest. One I have been using 90% of time.
Then:
Textured (sand) paint, mixed thin and painted on several times. (long drying time. easy to work with, but gets soft if spraying on colors or if it gets wet from set color applications.
Plaster- works fine, but not much time to carve before it gets hard. Which I prefer to do.
Sculptamold- probably the best and most workable. Expensive compared to plaster.
Celluclay-- long time setting, but can almost immediately begin carving and it holds its shape. Long drying time until coloring can begin. and you have to watch if wettness from coloring is applied. will soften. Cutting the mix with sculptamold makes it harder when dry and goes further.
Cletus
A much better alternative for mountains today is styrofoam. I have used a couple of methods. In the first method, I used the styrofoam blocks out of computer boxes or similar items, glued together with caulking compound, and then covered with an old towel, blanket, or whatever, for a very large mountain. This can be seen on the Cochise & Western Model Railroad Club’s layout (http://users.ssvecnet.com/cacole). I have found Casting Plaster to be the best, because it doesn’t crack as it dries, and it cures in 20 minutes or less. What I did was mix the plaster watery and pour it on from the top of the mountain and let it naturally flow, and spread it with a cheap paint brush where it didn’t flow. Several coats were added until it got stiff enough. Water-based paint can be mixed into the plaster to color it as it is applied, but paint makes the plaster set faster, so you have to work fast.
The second method I have used is to stack 1" thick styrofoam sheets to the desired height, glued together with caulking, and then cut into shape with an old bread knife. Casting plaster was then applied directly to the foam without the need for a cloth covering.
cacole’s idea of using the styrafoam is the best way to build the mountains…I use a little of both…plaster of paris and styrafoam…the plaster is used to hold the styrafoam together and to fill any cracks that may be present in the styrafoam joints…but to answer your question…use the plaster of paris…it dries very rapidly and holds up under stress a whole lot better than joint compound…joint compound has to be put on thinly because if it’s thick it takes way too long to dry and after it does dry you’ll experience cracks everywhere…the only place i’d use drywall compound is to tape and float a wall or build sections of old roads from it…the cracking looks good on modeled roads…not on the mountains…Chuck[:D]
Hey has anyone tried crumpling up brown grocery bags and diluted drywall mud? GRREEAAATTT!! Actually I start with the cardboard strips and a couple layers of heavy paper towels with the soup and then the last layer or two is brown bag. Then you can finish off the scenery details a little at a time.
I use cardboard webbing covered with MEDICAL plaster gauze and finish up with a thick coat of Plaster-of-Paris. The plaster gauze is strong by itself and the Plaster doubles that. Plaster of Paris sets pretty darn fast, but you can use distilled water to slow it down a little. Make small batches only. Very good results with this method in strength, money, labor, and looks.
The Medical plaster gauze is a lot cheaper than Hobby types. If you buy it by the case it will cost about $4.00/6"x20’ roll. While gauze obviously will cost more than towels, the strength is worth the investment. You can get the medical gauze at a med supply house or ask a medical type friend to help you.
You can also cover wadded newspaper with the gauze for the smaller hills.
Try a couple of capfuls of vinegar…vinegar works really well to slow down the drying process…Chuck[:D]
On my layout I have used several methods for making my mountains. I have a mountains range that runs 24 feet in a L shape that my trains run on in 2 levels.
Hard shell made from industrial paper towels from car parts store dipped in joint compound. You don’t have to rush and worry about the setting time of plaster. This made a good first layer, but it doesn’t harden the way plaster does and it doesn’t have a good detailed finished look.
I have used rock molds with plaster of paris over the drywall compound in some areas, but for the size of the area I needed to cover it would take forever.
I used the old tin foil rock method from the Aug 67 issue of MR.
Take a piece of foil (6 X 6 inch is easy to work) with crumple it gently. If you wadd it up into a ball the wrinkles are too fine and it looks spider web like.
Then gently spread it back out.
Mix the plaster at 2 parts plaster to 1 1/2 water ratio,
Pour the plaster on the foil, about a quarter of an inch thick.
Spread it with a spatula or your fingers.
Mist the hard shell area you are working on with a spray bottle. Not too much if you are using a joint compound hard shell.
Then put the foil and plaster in place.
I was able to create some nice strata layers, where I made quater inch and half inch fan folds running the length of 2 foot by 1 foot sections of foil. You don’t need to pre-wrinkle the foil, the fan folds will do it as you wrestle with it.
When I placed the foil mold on the hard shell I angled some of them at a four to six degrees to simulate the rock being thrust upwards.
I have also used 1 inch sheets of styrofoam from home depot like another member described that I to make tunnels and sereral lift off sections for easy access And then coated with plaster .
Cost is about the same for plaster or joint compound. But plaster is better for carving and taking stains. Joint compound
Around here many use joint compound and it seems to work fine for modeling low hills and general terrain. It cracks but so do many rock formations and doesn’t really present a problem for us. For mountains, tunnels and such, our techniques vary but usually use some sort of foam, and/oror the Hydrocal soaked heavy duty paper towel over some sort of cardboard strip webbing generally. If I were doing this I think I would use cheesecloth in place of the paper toweling.
I haven’t tried this but I think I heard some place once that you can do the bulk of your landforming using joint compound, and then apply a layer of Plaster of Paris over for strength and “carveability”.
Some will dispute this, since foam is highly flammable. You can use it, and the chance that your layout will ever catch fire is slight, but if a fire ever does get started in the layout room, good luck getting it put out. And burning foam fumes are toxic.
Plus running feeder wires, turnout linkage, etc through the foam can be an issue.
Call me old fashioned, but cardboard strips, hot-glued together, covered with 2" masking tape, goes in really quickly to get a basic idea of the scenery contours. Then I paint a plaster, cement, and vermiculite mix on the masking tape because it has a nice gray color to it, is lightweight, and has an almost “rubbery” texture to it, making it easy to poke holes in for planting trees.
If you haven’t gotten the idea by now, joint compound is great for filling small cracks and holes, but not over large areas, in thick applications, or in applications that take any kind of stress. It is much easier to work thatn plaster due to the drying time, but it will not hold up to any kind of a beatins, which plaster will.
Ron
Joe ; I agree with you on the dangers of using foam, BUT – like you said , chances of it catching fire are low. Not much electical current there in a 12v short circuit . Your same argument could be used for curtains, couches, pillows , comforters,etc. People smoke ; there are shorts in house electrical lines; people get careless with candles , faulty appliances,etc. , etc. No reason to get people paranoid about their couches ,drapes bedding etc…Wire properly and unplug the layout when finished. Use with proper care, like everything else in life.
Before ever considering to use joint compound for roads, small cracks etc., try using durabond. It sets rather quickly (15- 30 min working time) However when dry is much harder than j-compound and somewhat water resistant. Resists cracking and very little shrinkage. I don’t typically use either product on my club layout though. Scenery is wire screening w/ unical plaster base- masonry dyes added to the plaster for top coats-various browns represent earth w/o having to paint before applying ground foam. Rocks and outcroppings usually are rock castings of dyed hydrocal. Masonry dyes come in various colors w/ black, brown and brick red being the most popular. Add powdered dye to the plaster this color will represent a slightly lighter than the final product.(think of tile grout) once wet the color is very dark will lighten when dry. For very steep/ large cuts I can only recommend Laying up layers of plaster and carving the cut face-the colder the mix water the more working time, also when carving hardened plaster wet it down as you work . Dry scoring/ gouging can also give the ragged and chipped look. Roads and parking lots are done using heavily dyed unical spread w/ putty knives/ trowels. many times roads when dry only need final weathering and lining.
Some areas of the layout have been sceniced using polyurethane foam(pink or blue) hot wire cut and stacked , Glued w/ ceramic tile adhesive using a notched trowel. This adhesive was happened upon by accident during a school project- give it a try if you glue up foam- cheap,fast tack ,high strength and water clean up beats liquid nail any day. Weighted down overnight and is ready to continue.
Bob K.