Model Railroad Terrain - Rocks and Outcroppings

Once you have your model railroad terrain created, using whichever method from our last post, you are ready to add some rocks and/or outcroppings.

When initially creating your terrain, I find it's easiest to plan ahead a little and create some flat surfaces to add my rock outcroppings to when I reach this stage. (More on this a little later on)

Using Commercial Rubber Molds

Material needed:
* Rubber Rock Molds
* Hydrocal
* Spray bottle with water and a couple drops of dishsoap

Rubber Rock Molds are available in a variety of styles. Choose the ones that work best for what you plan to do, simple rock outcroppings in a hillside, mountain face outcropping, or a rock wall. Try and match the molds design to the area you are modeling.

Here's one example Woodland Scenics Rock Mold Facet Rock

You can also make your own rubber molds, I've outlined how to make your own molds in an article here. You don't need a large number of molds, you can turn them upside down, rotate them a little, distort the mold when casting the rocks, etc to create a varying rock face using only a few molds.

Hydrocalis a plaster-like material that is used to make the rocks. I have used simple Plaster-of-Paris, but I think you get better detail using Hydrocal. It's also lighter than plaster, a factor if you ever need to move your layout.

The spray bottle of water and dishsoap is used to lightly spray the molds before you pour the Hydrocal. It helps makes freeing the rock from the mold easier, once it has dried.   

Steps to making rocks:

* Prepare the rubber mold by lightly misting the inside with water that has a couple drops of dishsoap added. Don't douse the mold as you don't want bubbles remaining in the mold as this will decrease the detail of the mold. As I stated the water and dishsoap makes it easier to remove the rock from the mold.


* Mix the Hydrocal according to the directions. I actually make it just a little thinner as I feel it gets in the finer detail of the mold better. Don't make it to soupy or the resulting rock will be brittle.

* Pour the prepared Hydrocal into the mold. I try and "tap out" any bubbles by lightly tapping the mold on a solid surface.

* Allow the Hydrocal to dry. I've seen examples of the molds being applied directly to your terrain before the Hydrocal is dry. I haven't had the best luck with it, but, the idea is to wet the terrain you are applying the mold to so the mold sticks better. Allow the mold to dry right on the terrain, and gently peel the mold off leaving your rock face.

I have good luck thoroughly allowing the rock to dry and then securing the rock where I want it. I wet both the backside of the rock and my terrain which is usually plaster cloth or something similar. Wetting both surfaces helps the plaster adhere much better. Once applied, simply let it dry. I then use some Hydrycal, Scuptamold, or plaster to blend the rock into the terrain as needed. This is why I try to create flat spaces where I know I'll be wanting an outcropping when I'm building my terrain, as eluded to earlier in this post.

That's it. It's a very simple way to create great rock outcroppings and doesn't take a huge amount of artistic talent. Until my next post you can catch of preview of how I paint my rocks in an article here.

I do like to wait and paint my rocks after they are applied. I find it's easier to blend the colors by painting the rocks at the same time I paint my terrain. Pre-painting the rocks makes it more difficult to get a good match with the terrain. But it can be done either way. Try this technique out let me how it works for you!