There are a lot of rocks on the Greeley Freight Station Museum and the Oregon, California and Eastern model railroad, and the color is always consistent. In this video, David Trussell demonstrates how he creates those consistent colors. David uses rock remodeling from Risk Canyon, which is the same as done with Canyon and Colorado. This is the color we’re trying to accomplish.
He starts with a piece of Hydrocal that’s cast off a lump of coal. He sprays on the basic light colors first. Using Naples Yellow, he squirts it onto the rock, making sure it’s all covered. He then sets it aside to dry overnight. Next up is the darkness scale. Using raw sienna, he coats it first and then takes a piece of towel to blot it ever so slightly. This way, just a little bit of that secondary color is removed.
The next orange color may look scary because it just doesn’t look realistic. However, after blotting it very well, it adds a natural orange tint. Next, the darker color goes on. This darker color is actually a watered down India ink that David sprays over the rock. After blotting, the India ink is left in the cracks in the rock, adding great contrast. Once completed, the rock looks almost as good, if not better than the original version.