Since Dartmoor is largely made of granite it largely follows that most structures on the moors utilise this hard and heavy stone.
Curiously, a by product of the aging of granite is china clay. At school we referred to it as rotten granite. The southwest remains one of the most important producers of china clay in the world and its transport to more industrial areas is still largely done by rail.
Anyway, significant permanent structures on the Boltorr branch will be built of granite, or at least, I hope they’ll look like they are.
I’ve tried a couple of techniques. I rejected using embossed plastic card because it looks rather too sterile and certainly too flat. But, so far I think I’ve achieved the best results with air curing clay over foam board.
The dam was made by gluing a thin veneer of DAS clay over the board structure, then embossing stones onto the surface. This worked fairly well, but the results do not match the technique I have settled on. That is to make dressed stone looking chips of clay and sticking them on individually.
This sounds tedious, and to a degree it is a bit more labour intensive than just embossing the stones, but it’s far more satisfying and gives a more realistic 3D surface texture. It also make it easier to place reasonable looking corner blocks, cornices and other embellishments.
The building blocks are made by rolling DAS clay to a thickness of about 1mm. I do this by using a crumpled sheet of non-stick aluminium sheet – as used in cooking – a couple of coffee stirrers or similar and a clay roller.
The clay “biscuits” take up to 48 hours to completely cure and dry. Then I just break them up as randomly as I can aiming for blocks with sides around 4mm to 6mm long. This represents 12-18 inches to scale. Some end up a little larger, some smaller. It doesn’t matter. Any that seem too big I just break in half.
Corner blocks are made by cutting strips from the biscuit and snipping off appropriate blocks squarely with a pair of side snips.
Since these structures are purely functional a bit of variation adds to the charm, so I measure very little. It just has to look right.
Next: How to build a granite dam…