Bolt Tor Tunnel Portal

I’m pretty sure that the rest of the granite structures on Boltorr Road will not be made in this manner.

Manufacturing and applying hundreds, if not thousands of clay chips to represent rough hewn granite blocks certainly gives a very nice authentic appearance.

But frankly, covering possibly hundreds of square inches in this manner would pretty much define my spare time for the foreseeable future.

So the rest of the major structures on the layout – the reservoir dam, the rail bridge and Boltorr road over-bridge, will be built using plastic card embossed with a more dressed stone pattern.

Since the Bolt Tor tunnel was originally built by French prisoners from the Napoleonic wars for the plateway used in the construction of the reservoir about fifty years before the railway commandeered it, it can look a bit rough.

The more modern features will look as if they were built by skilled Victorian masons.

Anyway, that’s my excuse.

The basic structure was fabricated from 2mm MDF and random pieces of very thin chip made from DAS clay.

The clay was rolled out to about 1mm thick onto non-stick aluminium foil which previously had be scrunched up and carefully unfolded several times to give a textured surface. This was left to dry/cure, for me, around 48 hours.

The layers of very thin clay was then broken into appropriately sized chips to represent individual granite blocks. Dressed stones required on the arch and elsewhere were cut out with a pair of side snips.

The individual blocks were applied by spreading a thin layer of PVA glue onto the surface of the MDF, about an inch square at a time. The PVA causes the edges of the clay chips to become a little softened so it’s easy to get blocks to cosy up to each other in quite a realistic way, using a pair of tweezers to position the chips.

Once again the model took a couple of days to completely dry out so that a rough coat of dark grey acrylic paint can be applied. You can just dab the paint on since you are looking for a natural variation. You really can’t mess up to the degree that needs undoing at any point in the painting of the stones.

Once again, let the model completely dry out. Believe me, the MDF and clay soaks up a lot of liquid which takes many hours to dry.

I represented mortar and other general weathering and variation by thoroughly mixing up a small batch of whitish acrylic paint – 1 part paint / 2 part water + 1 drop of dish soap / washing-up-liquid – in a small dropper bottle.

To treat a surface I laid it horizontally on the bench and just dripped the wash onto the surface and let it soak in and dry. I repeated this process a couple of times on each surface until I got the result I wanted.

Once this was all dry – another couple of days – I picked out some random blocks and used a tiny paint brush and some black and white paint on a palette to give some more variation to the surface of the blocks.

It might have been better to have done this during the adding “mortar” stage, but it seemed to blend in with a bit of buffing with a dry, stiff brush.

The portal is now at the point where I can fit it onto the layout and blend in the landscape around it. It needs a little more weathering work, water and mineral stains, and once in situ a couple of plants/ferns growing in niches to add a little more detail.

Anyway. If I can do it, so can you.