Phil's Practical - Model a rock face

06 August 2020
Rock faces are very handy on a model railway. While the prototype tried to avoid blasting its way through the countryside, we are often faced with a need to bring lumpy hillsides and flat track beds together and so a steep-walled cutting is a necessity. Producing a realistic model of one can be another matter altogether.

American modellers love mountains and cliffs even more than we do, so it's no surprise to see a brand new product appear in the Woodland Scenics range to make life easier. Shaper Sheet is an ingenious foil-backed cloth that arrives on a roll but can then be bent and creased as required. The thick foil ensures it has strength and retains its shape.

To support the rock face, we carve up some 4-inch thick polystyrene. A Proxon hot wire cutter made quick, and not too smelly, work of this, a bread knife or saw would work just as well, but it would be a lot messier. A pretty basic shape is sufficient as all the fine detail is provided by the shaper sheet material and plaster.

Shaper Sheet is a foil-backed cloth material. To use it, simply cut a length slightly longer than required, screw it up and then flatten out again. Here, the sheet is bent over the polystyrene and fixed with “No more nails” thick white glue.

Although you can use the cloth surface on its own, the best idea is to cover it with Carving Plaster. This needs to be mixed well before use, aim for a texture like double cream. Thick but spreadable.

To smooth the rock face a little and add some strata, drag a damp brush over the surface, trying to keep the lines horizontal. Keep washing the bristles as you work, and the effect will be a lot like sandstone. Leave to dry overnight.

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The Earth Colors kit contains 8 pigment bottles and a foam brush. Before use, the pigments have to be thinned in water. One part pigment to 15 to 30 parts water is about right. More water just results in a lighter colour.

Pick a couple of base colours, 'raw umber' and 'slate gray' in this case, and dab them randomly over the rock surface, letting the colours run and blend on the plaster. Once dry, the rock face should be sealed with Scenic Cement sprayed from a hand pump or airbrush. We used an empty shower cleaner spray bottle that had been well washed out.

Finally, shading is provided with a wash of black. If the result looks too dark, spray with salty water and the paint fades.

The finishing touches are bushes made from lichen around the base, and scatter material on the top, while also providing leaves on the bushes. The process is quick and easy, but you do need to allow time for the plaster and paint to dry between stages.