General Discussion (Model Railroader)

Here's a brief description of how I make rock strata. There are other ways to make rock strata, but this method works best for me.

I will be typing directly into the forum now. If you will bear with me while I do that, I will appreciate it.

First here's a couple of completed locations that include scenic details. I sometimes include some stone retailing walls in a scene to add variety.

NEXT >>>>>> "Before and after"

BEFORE:

In this location, the lower line is descending from left to right. Meanwhile, there's the mainline ascending from left to right. Above it is the end of a branch line that enters the scene from the right.

AFTER:

Here's the completed rock strata. The scene is not totally done becuase I should add more scenic materials and some details.

>>>>>>>> NEXT ..... stuff you need.

You need the following material:

Plaster of Paris, construction adhesive, lightweight spackling compound, spray bottle with water and dish detergent, artist acrylic paints.

You need the following tools:

Calk gun (adhesive), flat pan (cheap, disposable, aluminum broiler pan), utility knife, common putty knife, small wire brush, single edge razor (in wallpaper hanger tool that hold blade)

STEP ONE:

Mix plaster making it more watery than normal and pour into pan to about 1/4" thickness. The thickness can be varyable to some extent because it will make final result more realistic.

Break plaster into pieces.

The pieces in the bucket are to be broken into smaller pieces when the are installed.

Next step is to install broken plaster pieces using construction adhesive. Each plaster piece should be broken to an appropriate size.  Try to select pieces that fit together closely. You do not want perfection, however, as you fit pieces together. It will look better for some rocks to protrude more than others. I will take care of gaps between pieces in the next step.

If a pieces has lumps on top or bottom surfaces, srape them off. Use plenty of adhesive by try to keep it from oozing to the visable face of the strata.

The blue foam board is optional, but it will make the strata more sturdy if you place it behind the palster pieces and use adhesive to hold the plaster pieces to it.

I should have mentioned earlier to protect trackwork as needed with plywood or other suitable material.

Now, it's time for gooey hands.

The cracks need to be filled. I've tried using plaster for this part, but lighweight spackling compound works better. Spray the rocks with a solution of water and dish detergent. Only use a tiny amount of detergent because you do not want bubbles all over the place.

Then, get a handful of spackling compound and work it into the cracks. Spray more detergent water onto the surfaces as needed. Try to get all of the spackling compound into the cracks.  

NEXT: BEGIN COLORING.

Here's why I prefer plaster over other materials such as broken ceiling tiles. The plaster can be made to have more realistic colors.

It's important to remember to use only watered down colors. You need a very thin mix. Each layer of color will make only a small change in the color of the surface. It will take many layers of different colors. Each layer must be completely dry before another layer is applied.

Important. Remember ........... Very thin coats.  Dry completely before next color is applied.

My choice for the first color may surprise some of you. I will post the picture next.

Before painting cut out some of the adhesive that oozed out. If some still remains, however, don't worry. You will not see it later on.  

The first color is YELLOW. Trust me. I know it looks like the family pet had some sort of an accident, but use yellow on the first coat anyhow.

Some of the yellow is too dark. After it's dry, I lightly brush the part that's too dark with a wire brush using only horizontal strokes.

After the yellow is completely dry, mix a small amount of raw siena color with water. Each color will have a few drops of acrylic mixed with about 4 oz. of water.

As with the yellow paint, a use a one inch paint brush to quickly spread the color on all exposed surfaces. Work the color into each of the crevices.

After the raw siena is dry, you can start to see how the surfaces may appear at the end of the process.

There may be areas where it will look better if there are more crevices. You can add crevices with a putty knife. Use a board to keep the putty knife horizontal. Press a corner of the knife into the dry plaster and pull the knife backward along the board. Repeat until the groove looks deep enough. The length of each groove should be variable Perhaps, 2 oto 4 inches is about right. Then use the knife to chisel out small random chunks of plaster either above or below each of the grooves.

Then use a wire brush horizontally to remove extra acrylic colors as needed.