In the quest for a realistic scenic product for my next layout that is light in weight, easy to work with and low cost with a natural and lifelike appearance I made one of the greatest discoveries of my railway modelling journey at the “N SCALE CONVENTION” held at Quakers Hill in Sydney N.S.W. My thanks go to Mark and Angela Fry, (the creators of the award winning layout “SWANS CROSSING”, who ran a clinic on ‘Soft Rock’. This article is based on what was taught. I also, with Mark’s permission, was able to videotape the clinic.
The most obvious advantage of this technique is the significant weight reduction and flexibility of the rockwork. A soft rock is chip proof, readily altered and/or removed and this is completely recyclable. The raw materials are easily obtained and are literally ‘dirt-cheap’.The size of the soft rock is only limited by practical application; they can be made as small as a pebble to an entire mountain range.The technique lends itself particularly to exhibition style and portable layouts due to not only its inherent lightness but also to the ability to butt-tip on module joints completely disguising them. This has proved itself on my latest layout ‘Snowy River Canyon’. One final advantage with this technique, which sets it apart from any other rock building method, is the ability to create rocks which have reverse curves within them including caves/caverns etc.
1. Using a broad tipped felt pen, mark out on the foam rubber an approximate rock shape using a photograph as a guide.
2. Cut around this outline with a ‘snap-off blade knife’. I use an electric carving knife.
3. Carefully slash some horizontal grooves of varying depths and carve out from the sides of the rock across the face. 4 Using a ‘Surform’, (Rasping Tool) round off any angular protrusions on the foam to create a more rounded weathered look, if applicable to the rock type, eg. Sandstone.
5. Additional weathering effects can be achieved with the ‘Surform’ on its side to gouge out sections of the rock face (remember to vary this to avoid uniformity) or use your fingers to pick out cavities as in honey combed sandstone formations.
6. Smear liberal amounts of Selley’s brand “NO MORE GAPS” all over the rock face, completely covering the foam. This also contributes to the final texture and in some cases could be the texture alone depending on the rock type. (See Variations).
7. Working over a tray, sprinkle on samples of the rock coloured sands you have collected and sieved, (In Australia I have found ‘Chuck’s Ballast’ has a good range of ready to use soil types), covering the foam excessively ensuring the sides also receive ample coverage.
8. Lift the soft rock and lightly tap the back of the rock to shake off the excess materials. These can be recycled and used on the layout. I have found that a light spray with a cheap Hair Spray will help hold the material on while drying takes place. Place your new soft rock on a sheet of newspaper and leave in the sun for two days days or until dry.
Once dry and a number of rocks are ready to be placed on the scenery base (which can be plster shell, polystyrene foam of wood) position ‘soft rock’ using photographs as a reference and adhere with a hot-glue gun. Gaps between rocks can be filled with ‘No More Gaps’ and scenery materials or recycled excess sand colours. Once basic rockwork is complete, paint in shadows using ‘Oil-wash’, and water streaks using Polyurethane Varnish, eg. Tamiya Sky Grey for grey sandstone effects.
As mentioned earlier a number of different types of rock formations can be made but are dependant on:-
1. Carving and Shaping: The carving and shaping of the foam rubber helps identify the rock type. Essential for this are some good colour photographs of the rock type you wish to model. Carving and shaping, can be done, not only by the use of a razor knife, fingers and surform but also by scissors, electric knife or suitable solvent, but beware of the fumes of the dissolving foam rubber. The beauty of this method is that it is so forgiving, if you carve off too much foam rubber in a spot, leave it and in-fill with some vegetation outcrop etc. or when it is glued to the scenery base cut it out, throw away and start again. Chances are no one will notice your mistake once it is all done. Study and look for the dominant strata lines or erosion effects of the rock in your photos.
2. Foam Rubber Density: The density of the foam rubber type you are using also helps determine the rock types you may wish to model.
3. The Texture Medium: Apart from the rock shape helping to identify the type of rock the application of the texture medium also contributes largely to this and makes it look more lifelike. Through the careful use of the texture medium this technique can be used in HO to Z scales. Generally the texture medium consists of sieved or unsieved soil of appropriate colours to the area modelled or rock type. Collect suitable soil types from railway cuttings, dirt roads, building sites and riverbanks to name a few. I always carry a plastic container in the car boot and sometimes get strange looks when collecting interesting soils. For finely grained rock I use finely sieved soil types, whilst for coarse rock use unsieved or lightly sieved soils. As mentioned in the “Procedure Section” ‘No More Gaps’ also contributes to the final texture of the rock, this being achieved by the use of different paint brushes or spatula etc. dipped in water and brushed over the already spread ‘No More Gaps’ skin. Paint pigments can also be applied directly onto the ‘No More Gaps’ and over the soil types of a conventional soft rock for more varied and pleasing effects Grey Tile Grout as a texture medium can be used And has produced some fine examples of granite boulders in the process.
The use of foam rubber as a medium for making rockwork can be further expanded. There is no reason why the entire scenery base could not be foam rubber provided the trackwork is firmly anchored to a soundly secured roadbed and suitable subroadbed and framing. The actual method of making soft rock can be applied to making entire landscapes of foam rubber. The foam rubber is quick and easy to carve, leaves little mass or dust and is totally recyclable. The downside of this is the cost of buying your foam rubber direct from a commercial retailer. It is best to look for foam rubber manufacturers and buy direct or look around for an old lounge or foam mattress (but not too old). The rockwork on “Snowy River Canyon” was made from one old Lounge Chair with plenty to spare. The original and best scratchbuilder of them all (God) gave us many beautiful landforms including rock formations to model. Soft rocks are just another means of trying to achieve this. Have a go at it and have some fun creating your own model landscapes just as He did in the beginning.
Broad tipped felt pen
150mm x 200mm sections of foam rubber between 10mm and 50mm in thickness
1 x cartridge of Selleys ‘No More Gaps’ or similar and 1 Cartridge Gun
1 x sharp snap-off blade disposable knife, large blade type
1 x small curved Surform
1 x large tray and a Container of water
1 x medium sized disposable paint brush
Photographs of desired rock strata
3 x different rock-coloured sand types finely sieved for N Scale and/or finely grained rock
1 x jar of Oil-wash (1 – 1 1/2 teaspoons India Ink and 345ml of Rubbing Alcohol mixed together
Newspaper and Hot Glue Gun
Tamiya Sky Grey (for sandstone formations etc)
Urethane varnish (gloss/high gloss for water effects)