I have seen different kind of rocks on pictures but I don’t know what the types are called. The reason I ask is because I want to learn more about modeling rocks and rock molds. The rocks in the royal gorge, where the D&RGW hanging bridge is located, what kind of rocks are they? And can I buy rock molds for that purpose somewhere?
You ask a huge question.
First, Woodland Scenics, along with others, sell good rubber rock molds.
Second, you need to do a little reading on Geology. Knowing a little about where the rock formations came from helps. Sedement rocks are different from volcanic and from tectonic. To model different rocks, it is helpful to use prototypical techniques. For instance, for sedimentary, carve lots of horizontal lines. If tectonics are included, the lines will not be parallel with the horizon.
Third, after a little study you start to recognize rock types and can then look at molds and see styles.
Fourth, there is no substitute for practice and refinment of skills. If you like scenery, I think you will find the crafts challenges harder than the artistic.
Keep us posted with your progress as we are all learning together.
EL, if you intend to use Joe’s formula for plaster in creating your topography, you will do fine if you also copy his technique in carving shale and sedimentary strata during the setting of the second layer, as he describes. Study the Gorge photos that you can find, and if there is sedimentary stratification, a putty knife and the texture of the material are all you will need…I’m quite certain of this.
-Crandell
One technique I have heard about but haven’t tried yet is to use expanding foam instead of plaster in the rock molds. I see several advantages. One is that it would be light weight and wouldn’t be as brittle as plaster. I don’t think it could be carved as easily as plaster after it sets up. Also, I would be careful about using too much because that stuff really expands a lot. My expierience with it in other applications tells me it might stick to the mold so I might try coating the mold first with cooking spray or maybe sillicone.
A terrific source of assorted rock molds can be found at Bragdon Enterprises. You will also find supplies and instructions for the foam technique if you want to try it. I’ve seen it demonstrated at shows and it is extremely light-weight and easy to use. The downside, it seems to me is that it is more expensive than plaster and does require several steps to achieve the desired results. Also the rocks have to be painted, not stained,as with plaster castings. Nevertheless, the molds, while a bit expensive, are large and can be manipulated around so that the same mold can produce multiple scenes. You might want to check out their site for yourself. Good luck.
Art has really laid out the basics for rock formations. When scenicing igneous outcroppings and blasted cuts you not only need to know the proper molds but proper mold orientation is also required. Once you are satisfied with the type of molds, and you should have a good half dozen or so, examine the strata orientation for placement. I have even made sample castings and numbered them to correspond to the mold and marked position orientation w/ an arrow. I do this so that doing large cuts the rock will look more natural when the next selected mold is to be placed. Many times I don’t just glue the cured molds to the base, I place a partially hardened mold and hold until it is firm. By not seeing the actual casting in the mold the sample tells me the position. This past week I have started a few areas of the club layout where these particular molds are to used. It’s been about a year since the last session and I need to sharpen my skills and get the hang of it again. The next area is a very long and tall cut for the mainline and it is right in your