I’ve started a new building for my In-kopah Railroad. This will be the first building in the town of Mineral Ridge. It will also be an experiment in using PVC foam board (aka Sintra) and resin castings to simulate the look of stone construction. In the past I’ve used only real stone for my stone buildings, bridges and retaining walls, but there are limitations to what can be done using real stone. Since this building will be surrounded by real stone cliffs as well as foundations and retaining walls made of real stone, it will be crucial to get the simulated stone to look right!
A while back I did a real “quick and dirty” test on a scrap of PVC to see if it was even possible to texture it to look like a stone wall. Here’s what I came up with:
It’s far from perfect (though the photo doesn’t do it justice), however I know how to improve it. So I’m forging ahead…
The design of my building was inspired by this historic brick-and-sandstone structure:
Mine will be narrower, with different details, and the side wall will be of rubble stone construction rather than brick. Due to its location, only the front and left side of my building will be visible, thus only those two sides will need to be textured. I started by cutting out the front and side walls from 6mm PVC. The left wall will be worked on first. I marked the locations of the quoins with pencil:
Next I roughed up the surface by tapping it firmly with various rocks:
Then I used a carbide-tipped metal scribe to scribe a pattern of random stones into the surface. After scribing the stone pattern, I added more texture by tapping it with rocks again:
Here is the completed wall. The area at lower left will be hidden by a “boulder” so there was no need to detail that section:
Here’s a closer view of the texture:
Next I glued the front and two side walls together, and tested the fit on the concrete foundation:
The foundation was faced with thin stones, glued in place using paintable silicone sealant. I still have to make the sidewalk and stairs:
Here’s a wider shot of the town site and in-progress structure:
The front wall has sections which stand out, so I cut some 3mm PVC and glued it in place:
I also cut a subfloor from 3mm PVC and glued it in place. In this shot of the underside, you can see the strips of PVC and styrene that support the subfloor:
Now, the big question was, How to replicate the rough-hewn faces of the rectangular sandstone blocks? The method I chose is as follows… First I cut some 6mm PVC into strips of two different widths. Then I used a sharp hobby knife to carve the upper surface of each strip, as shown below. (I carved these during a two-hour wait while my wife was getting some medical procedure done.)
These strips were then cut into individual blocks, and the ends carved to shape. I decided the texture needed to be a bit coarser, so I used an old craft paintbrush to stipple a thin, irregular coat of automotive spot putty onto the face of the blocks:
I then glued the blocks to a scrap of rigid plastic sheet, and built up a low wall of styrene strips around the perimeter in order to make a silicone rubber mold:
Here’s the silicone mold:
I poured urethane resin into the mold, covered it with a piece of thick plastic film, and topped that with a flat, heavy plastic sheet. I don’t know what kind of plastic film I used – it came from a large bag that brass screen was shipped in. But it’s a pretty common type, and the resin doesn’t stick to it. After the resin cures, the plastic peels off easily and the castings are popped out of the mold. I added some colorant to the resin to make the castings light gray. They’ll be painted, but this way if the paint ever gets scratched, it won’t show:
That’s as far as I’ve gotten for now. More to come!
