First time with plaster shell terrain - advice?

I’m about to try my first plaster shell terrain. I’ve got some black fiberglass screen and plaster cloth coming. I have seen crumpled paper for support as well as cardboard profile supports. I’m going to try the cardboard first as it seems like it will give more control over the finished product.

How is the cardboard mounted to the surface? A couple of bent pieces glued in place at the bottom? Some other techniques? I see lots of examples of what the terrain contour looks like but not much showing what’s underneath.


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Unfortunately I don't have any photos from my layout to share, but I typically cut the cardboard into 1" wide strips and hot glue them to the structure of the layout. Just as you describe, you can fold over the ends of the cardboard and attach to the layout. You can hot clue or staple them, or use any other adhesive of your choice. Hot glue's main advantage is quick setup time. I then "interlace" or weave the strips and build p the scenery support from there.

Crumpled paper makes a good support as long as there's something for the paper to rest upon. Then I suppose that you can either hot glue or staple the black fiberglass screen over the basic form and then start applying the plaster cloth.

However, if you weave a tight enough lattice of cardboard, you may find that you don't need the screen.

 

Another method is to build it up with foam sheets. Cut layers to the profile wished, trim to get closer to profile wished and then if desired us cans of foam that is like whipped cream to file in voids and smooth the profile. Then when the glue and foam are dried cover with plaster adding more shape if desired.

 

Plaster isn’t the best material for layouts, it’s pretty weak. Most use Hydrocal, which is a cement, not plaster.

Thin shell scenery sounds great until you plant trees. The trees will soon point in every which direction, since there’s nothing to hold the “trunk” from rotating.

A great way to color plasters or Hydrocal is Mortar Color. This color is mixed into the water before you add it to activate the plaster. Home Depot carries it in the cement section.

Setting plaster is exothermic, which means it heats up. Using hot water from the tap aids the heating process, resulting in stronger plaster or cement. Of course, it also sets faster but chemistry could care less about working time...

 

With hydrocal I use the same paint I use for ground cover in the mix. That way if you get a chip out scratch you won't see white.

 

The problem with paint is that it interferes with the chemical reaction. Latex isn’t plaster, so the result isn’t as strong.

 

cut your cardboard into workable strips (1" or so wide) and simply hot glue each end to whatever you are securing it to. Fairly easy. When you do plant trees and what not, a little bit of glue on the trunk will help hold it to the terrain. You may occasionally have a fallen tree, but personally I haven't had any real issue with fallen timber, even when I moved those parts of the layout to our 'new' house a couple years ago.

 

Wish I could remember were I saw cardboard cut up into strips for sale. I would check back to see what it costs. I don't get much stock to cut up.

 

Shortround....buy a sheet of plain white poster board and use that to cut strips. Those boards are a decent size and surely under a dollar.

 

Micro-Mark sells the strips under corrugated scenery strips. Item # 83081 Pkg. of 90 $ 12.95 1" x 24"

 

I've had good results with strips cut from corrigated cardboard boxes. The extra thickness of the corrigation structure is easier than solid cardboard to shape once both ends are hot glued and also supports trees better. Your nearest grocery store will give you all of the boxes you want.

 

I use old metal/aluminum window screen materials which holds its shape very well especially with an occasional 2x4 riser for support. The screen is often free at glass/window businesses in the trash. Then I use paper towel strips dipped in a soupy Hydrocal mixture layered over the screen.

 

building material yards have drywall butt shims by the large package, they are about 1 1/2" wide and 4 ' long to build up the thickness behind the drywall next to the butt joints to allow the mud to fill a depression instead of making a hump. They are cheap and ready to go. I have a large supply of yard sign wires and will use them to create a form between wood splines for my layout. I'm planning on drilling holes for the ends of the wires in the wooden splines. They are roughly #9 gauge and will form the same type of lattice as the cardboard method, but will also build tall hill shapes behind the last track into the wall behind. In traditional plastering this called the armature and is covered with wire lathe.

 

I will be curious to see your results.

After Gordon Odegard introduced foam scenery on the MR Clinchfield layout a lot of people switched to that. But I am interested in big rocks and mountains that look like the rockies. I once made a small layout using rubber home made molds and Durhams water putty. It was nearly unbreakable, but did not take paint well.

The Irony of that attempt is that I had used pink foam and before long the pink foam was completely encased in water putty molds. It seems to me the older cheaper method of woven stapled cardboard is cheaper and easier to work with.

I did really enjoy casting the rocks in place and blending them.

 

I am also going to experiment with using old blue jeans and Carhart cotton duck to make my own plaster cloth ( I have too many destroyed work pants).
My goal is to avoid buying small packages of things I can do my self. Although i have used foam in great quantities on buildings, I also try to stay away from such manufactured products if more natural exist. The plaster I'm using is molding plaster and comes in 50 lb bags. I use it to make architectural moldings. It costs about 30 bucks a bag, sets pretty quick and can be sanded or scraped or scratched in a hour or so (takes a long time to fully dry.)

 

Remember, plaster and hydrocal (recommended) is exothermic, which means it gives off heat when you wet it. Cold water absorbs the heat, and the reaction poops out before it’s done hardening. Use HOT water from the tap. It sets faster, but sets up really hard!

 

I would never use hot water' just plain tap water set up fast enough and still harder than rock. Just my take.

 

The call for hot water is on the instruction sheet. Is it hard with cold? Sure. It’s twice as hard with hot though.