The rock outcropping on the Union Pacific Cheyenne Division of John Gray looks so real. Because of the size of the layout and the fact that it was really built by Phil Gazzano, John Gray himself, and others, they tried to come up with methods that were not labor intensive. So they came up with a method using bituminous coal.
A plaster mock-up is used by Phil Gazzano to demonstrate the coal rock outcropping technique in this video. Phil uses vinyl spackling and applies it with a palette knife to the ridge top. This will become the attachment for the coal, working like glue. The beauty of this technique is that it can be used on finished scenery as the mess is very minimal. A finished scene can be returned to, and a rock outcropping can be added at any time. Next the coal is placed right down in the spackling paste with the straddle lines aligned. The outcropping won’t look real with varying straddle lines.
The next step is to take broken coal bits and fill in around the already placed pieces. Patting the coal bits into the paste with the palette knife really sticks them down. The next step is to take diluted white glue and water pour it over the placed coal and chips, fully saturating the surface. Too wet, and the smaller flakes will run away. Let the solution dry overnight to set the glue. Coming back, the next step is to coat the base rocks with a base coat of paint. In this case, Phil uses Floquil oxide red with a touch of white added. He brushes this on with a brush to coat all the crevices and cracks. This again will be left to dry overnight. For more tips on creating scenery or info on how to create rock scenery, visit the Model Railroad Academy archives.