1/24th scale simulated stone building

[Ray Dunakin]

I've started a new building for my In-ko-pah 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!

 

 

[Ray Dunakin]

Here's some more info about this project...

The material for the mold is called OoMoo 30. I like this stuff because you mix it in equal parts by volume, not by weight, so you don't need a fancy scale. It's also pretty forgiving of minor inaccuracies, so you don't have to worry about being super precise. It's made by Smooth-On, but I get it from this art supplier:

www.dickblick.com/products/smooth-on-oomoo-30-silicone/#items

The urethane resin I use is also made by Smooth-on, and is just as easy to use as the silicone rubber. It's called Smooth-Cast 300:

www.dickblick.com/products/smooth-on-smooth-cast-300/

It took me about a week to scribe the stone pattern in the side wall. That was doing a little at a time, an hour here, a half hour there. I did some of it in the waiting room at the doctor's office!

The small hole in the front of the foundation is drainage. There's a "pit" in the middle of the foundation for wiring the lights, and I don't want it to fill up with water when it rains. When I make the sidewalk, I'll have to include a "drainpipe" so as not to block the drainage.

I use PVC pipe cement to glue the PVC to itself. When I glue styrene to it, I usually use Weldon-16.

The stone block castings are 3/8" x 3/4". The narrower ones are 1/4" x 3/4".

A while back, I did an experiment with brick texture on PVC and got really good results. I'm planning to do a brick building next.

[Leon]

Ray thanks for posting.very nice work.

[multicam]

Wonderful SBS Ray. Very cool to read and inspiring. I've been daydreaming about stone walls and cobble stones, so this is great for me. Thanks for sharing:)

[deafpanzer]

Great blog... loving the result!!!

[Ray Dunakin]

Progress has been a little slow this week, but here's an update...

I made small sections of wall to be glued to the inner surface of the building's side walls, along the top. This provides texture for the small portion of the side wall which will be visible on both sides, and also makes the wall thicker:




Here you can see one of the pieces glued in place, along with a strip of styrene to support the roof:




And here's the roof glued in place. The roof was cut from 6mm PVC foam board:




When I built up the sublayers for the front wall of the structure, I scribed "board" into the arch area of the PVC foam. Now I've added some trim, made from styrene strips:




The interior rooms of the building will be removable units that can be accessed from the rear of the building. I got the idea from fellow modeler, Bob Santos. I built these from PVC, mainly 3mm thickness but also some 6mm. Here's the lower room. The ceiling is secured by stainless steel, #2 x 3/8" sheet metal screws. Strips of .250" x /375" styrene are glued to the top of the ceiling, to support the upper room at the correct level.:






Here's the upper room. The left wall of the room is recessed about 1/8" inch, to clear the window frame and glass which will be installed in the side wall of the building:




In this view from the rear, you can see how the interior units fit into the structure. The space between the upper and lower rooms can be used to wire the interior lighting. There will also be a gap between the rear wall and the back of the interior units, for wiring:




A closer view of the units in place. Note the slightly recessed wall on the upper unit, designed to clear the window frame and glass which will be installed later:




And here's a look at the lower room, seen through the front opening:




Next up was building the front door and window assembly. On my first attempt I tried doing it a little differently than usual, and was not successful. I started with a sheet of .040" thick styrene, and traced the opening onto it. Then I added the main frame pieces:




Before adding any further detail, I tried to cut out the window openings. The results were too crude -- having the straight edge raised above the surface by the frame pieces allowed the tip of the knife to wander slightly. Also, the knife left ridged that would need to be sanded down. I could have salvaged this, but it would be too much work:




So I scrapped it and started over. I first glued together the main frame pieces, cut from strips of .080" x .125" styrene. Then I used various sized strips of .040" thick styrene to build up what I call the "backplate" on the underside of the frame:




Then the finer details were added, using strips of various size. Here's the finished product:




Here's a closeup showing some of the details. I used .020" styrene rod around the perimeter of the windows and panels:




And here's the door and window assembly temporarily installed in the structure:






That's all for now. Enjoy!

[multicam]

Superb work, Ray! This is great! Very inspiring. I love the trim detail:) I can't wait to try this myself. Super cool. One question, when you say PVC, what are you using? Is this different from the evergreen or plastruct style styrene sheet/rod etc? Thanks for sharing and please keep it coming:) Great stuff!

Nate

[Leon]

Ray that is some scratch work.Details are well done.

[Ray Dunakin]

Thanks!

Nate, it's "Sintra" brand PVC foam board. Great stuff -- rigid, durable, made for outdoor use, yet easy to cut, sand or shape. I get it from this supplier:

www.foamboardsource.com/sintra-pvc-foam--sintra-pvc-board.html

[deafpanzer]

Stunning! Just great... enjoying this SBS very much! Really appreciate you doing this for us...

[multicam]

Thanks for the info, Ray. Very cool stuff!

[Ray Dunakin]

Time for another update... 

I did some more preliminary work on the front of the building. I had previously laminated some 3mm PVC foam board to create some raised areas. But I decided that the non-raised area above the upstairs windows needed to be taller. So I had to cut off some of the laminated material. After a bit of effort I got it off, however it damaged some of the substrate:




I patched up the damaged area with some automotive spot putty. It doesn't need to be perfect, since it will all be covered with stone castings later. I also decided to add the arched attic vents above the windows. Originally I had planned to use rectangular vents, but the arched vents looked so great on the prototype building, I couldn't resist them even though it means more work:




To make the attic vents, I laid out the radial "sunburst" design on a sheet of .040" styrene:




My intention was to cut out the indivdual openings, but this was getting too tedious for me. So I went to Plan B: Cut out the entire arc opening, then glue in bits of .040" x .060" styrene strips. It's not as elegant, but it works. Then I built up the frame out of curved and straight styrene strips, and added the "backplate". After it's painted, I'll glue some fine brass screen to the rear of the backplate:



Here's how they look installed in the structure:




The upstairs windows were built in conventional manner, starting with the large frame pieces. Then I added strips of .375" styrene to the rear of the frame as a "backplate". In this photo you can see how I used steel blocks, with a strip of .250" square styrene as a spacer, to align the backplate piece on the frame:




The finer details were built up using various strips of styrene. I cheated a little and built a fake sash into the lower part of the window frame. I didn't want to fuss with trying to cut glass precisely enough to fit into a real sash. This way, all I have to do is glue a single sheet of glass over the rear of the entire frame:




The side window was built the same way, but lacks the short section at the top:




Here are a couple shots of the building in position on the foundation, with all the window frames temporarily installed:





The styrene portions of the building (window frames, etc) are really pretty basic, and I'm sure for many of you guys I'm "teaching your granny how to suck eggs", but I figure it might interest someone anyway.  


The next phase of the project will be making the rear enclosure. After that I will be able to start attaching the stone castings to the front of the building.

[noll]

That is utterly badass.

Awesome!

[deafpanzer]

Great work again!!! You made it look so easy...

[Ray Dunakin]

Moving right along...

I did some more work on the interior, adding strips of styrene along the top of the interior walls to prevent vertical movement of the removable rooms:




I also attached strips of styrene to rear of the room units. When the rear wall is installed, these strips act as spacers to prevent front-to-back movement of the units. They also serve as convenient handles:




The rear wall is basically just an access panel. I made it from a sheet of 6mm PVC foam board cut to fit inside the rear of the building. On the outside of this, I laminated a larger sheet of 2mm PVC, to create a "flange". Hopefully this will keep out rainwater:




Here's a shot of the rear of the building with the wall secured by eight #2 x 3/8", stainless steel sheet metal screws:




The edge of the 2mm thick portion of the rear wall, was rounded off, then scribed to match the stone pattern on the side wall:




I cut a strip of 2mm PVC and textured it by tapping it with a rough rock. This was glued over the window on the side wall, to represent a rectangular, cut stone:




Finally, I get to the fun stuff -- mounting the stone resin castings! I used a drawing program to lay out some radial lines to match the arches. The lines aren't spaced to match the width of the stones, because I didn't know how to do that with this program. But they at least serve as a guide for getting the angles of the stones right.

I cut a bunch of the stone castings to fit the length of the arch stones. Then I sanded a very slight angle into the sides of each stone. I found it necessary to place the stones over the drawing as I made them, in order to be sure they all fit correctly. It is also important to start with the stone at the center of the arch, both when shaping them and when gluing them to the building:




This is how far I've gotten. I first glued on the stone castings along the sides, up to the top of the main window opening. Then I added the arch stones:




There are a few minor gaps which will be filled with putty later, and blended into the stones:




In this close up view you can see how I cut the stones at the sides, to fit around the end of the arch. I also had to cut a stone into a narrow strip to fill a gap at the top of the column. The stone castings turned out to be slightly smaller than the masters, resulting in some minor discrepancies in the arrangement of the stones:




When I installed the stones between the upstairs windows, I originally started at the bottom of the window and worked upwards. Then I discovered there would be a small gap due to the change in the dimensions of the castings. The gap can be filled with stones cut to narrow strips, however I felt it would look better if this was at the bottom rather than at the top. So I pried up the stones and reinstalled them, this time starting at the top and working downwards.




In retrospect, it would also have been better if I'd installed the narrow trim stones by starting at the center, rather than starting from the end. Then the stones would not have ended up off center. It's a minor thing though, so I'm not going to redo that.

You can also see some more small gaps that will need filling later.

Anyway, that's it for now -- more later!

[multicam]

Still amazing! Great SBS too. Keep it coming Ray! It looks awesome:)

[Leon]

Amazing work Ray.

[Ray Dunakin]

Got a lot more done...

I filled in the area above the main arch, cutting some of the stone castings to fit as needed. I also added castings on either side of the upstairs windows:




Between the windows and the attic vents, are stone slabs which are smoother than the other stones. I made these from strips of 1mm PVC. I used a rough rock to give the "slabs" a little texture:




The slabs are sandwiched between extra-wide stones. I made these by gluing together three regular stone castings, then using putting to fill the indentation between them. At first I used Squadron White putty, but it was too soft. Later I switched back to using the automotive spot putty:




I shaped some stone castings to fit around the attic vents, once again using a crude drawing as a guide:






After I finished the arches, I added the narrow, vertical stones near the top of the building. Alternating stones are mounted on strips of 3mm PVC. Before these were glued in place, I made sure that all the vertical stones would fit as intended, with a raised stone at the center, and a lower stone at each end. Once the vertical stones were in place, I filled in the remaining area, cutting some of the stone castings as needed to fit around the arches:




The next step was the fancy trim at the top of the building. For part of this trim, I needed a special shape that was built up from two strips of 3mm PVC. The narrower strip was cut at an angle along one side, and then glued to the wider strip:




The first "layer" of trim above the vertical stones is a row of thin stone castings. The next layer was done using 1mm PVC, with the same texture as the slabs. I built up the fancy bits at each end and in the center, using short segments of the contoured strip previously assembled:




In this closeup you can see some of the texture:




The two-piece, contoured strip that was assembled earlier, was smeared with putty and sanded using sandpaper wrapped around a dowel. I also applied the same treatment to the short segments that were already attached to the building:




The last "layer" of trim at the top of the building was made using a .250" x .375" styrene strip as a base. Short sections of 1mm PVC were added to create raised areas:




The top strip was finished with the application of stone castings:




And here's how it looks so far, nearing completion:




I still need to make some protruding thingamajigs for the top of the building, at the center and on each end. I also need to work on the quoins on the side of the building, as well as a few other small details. Later, I'll work on the interior details.

Stay tuned!

[Leon]

That is some awesome work Ray.Really like all the detail your putting into this.

[Ray Dunakin]

Thanks guys!

[bullardino]

This is one of the best SBS I've ever seen. Lots of techniques to learn and try, very clearly explained. Thanks a lot

[paulh.]

I got brain-ache- of the best possible sort
Yo0ur methods of building /scratching the dressed stone facings is sobrilliantly simple
Ray- can you confirm for me that the surface texture in the early shots is staight onto the card surface of the foam board and not onto a spackle/filler/plaster type coating?

By the way- have I said how much I like this and how inspiring it is

[406 Silverado]

I have to agree with Paul on this one. man my eyes bulged and jaw dropped as I scrolled and read through this. wow this is super helpful and I'll be making some stone work and molds in the very near future for something I have wanted to build for years.

[Ray Dunakin]

Mar 25, 2013 2:06:14 GMT -5 paulh. said:

Yo0ur methods of building /scratching the dressed stone facings is sobrilliantly simple
Ray- can you confirm for me that the surface texture in the early shots is staight onto the card surface of the foam board and not onto a spackle/filler/plaster type coating?

By the way- have I said how much I like this and how inspiring it is 

Thanks! Yes, the stone pattern on the side wall of the building is scribed directly into the surface of the PVC foam board.

[Ray Dunakin]

A little more progress...

I added pieces of .020" thick styrene sheet to the front corner of the side wall, to represent quoins. These were lightly textured by tapping on them with a rough rock, after they were glued in place. Because the resin rock castings ended up with different spacing than I'd originally planned, the quoins didn't match up with the scribed stone pattern on the side of the building. So I also had to add new scribing to fill in the blanks:



I built up the three decorations (crennelations?) at the top of the building, using layers of PVC foam board and some resin castings:






Now it was time to do something about the missing stairs and sidewalk in front of the building's foundation. I began by building a form out of 2mm and 3mm PVC. Here's a shot of the form, lying upside down. I scribed the inner surfaces to simulate wooden planks:



I bent a short length of brass tube and connected it to a small hole in the front of the foundation. This will provide drainage when it rains. Then I set the form in place, and secured it with hot glue. I used small scraps of foam core art board to seal gaps, particularly along the lower front of the form:




Here's a closeup view of the form, so you can see how it was put together. I had to make sure that no parts of the form would be trapped between the foundation and the concrete casting:




Then I mixed some high strength mortar and added a tiny amount of concrete colorant to give it a slightly darker tint. I poured this into the form, filling it about half way. When the first batch began to firm up, I mixed up some more and filled the form to the top. I skimmed off most of the excess mortar and then covered the top of each step with a strip of foam core art board, taking care to avoid trapping any air bubbles. I used a large piece of foam core to cover the sidewalk at the top of the stairs:




The following morning I pulled off the foam core strips and exposed the upper surfaces of the concrete. The steps turned out ok but there were many small air bubbles in the larger sidewalk surface. I sanded it down and eliminated most of the pits, then filled the rest with a thin layer of fresh mortar. When this set, I sanded it again, lightly, to smooth the surface a bit more:




Then I dismantled the PVC form and removed it. You can see some of the impressions left by the "planks":




Next I used a 1/8" masonry bit to drill some holes into the sidewalk and steps. (I wanted smaller holes but this was the smallest masonry bit I could find.):




I cut short segments of 3/32" brass tube and glued them into the holes, using paintable acrylic caulk. Sections of 1/16" rod were inserted into the tubes to aid in making sure the glued in as vertically as possible. Later, the excess caulk will be trimmed off, and eventually it will be painted to blend into the concrete:






When the caulk had set up, I removed the rods, coated them with solder, then reinserted them into the tubes. Then I soldered a scrap of square brass tube across all five rods, so that they could be removed and remain aligned. This temporary piece would be removed later when it was no longer needed:




Then I cut the tops of the rods off to the desired height and soldered on the horizontal piece across the top, following by the top angled piece. The end of the angled piece was bent around and soldered to the side of the upright rod at the bottom of the stairs, to form a simple handle. At this point I was able to unsolder the temporary piece of square tube. Then I soldered in some shorter pieces of rod to create the lower rail. My soldering method is pretty crude and results in lots of excess solder on the material, so when I was finished I filed and sanded down the excess:




The finished handrail was cleaned, then primed and painted gloss black. Later I will weather it. I also have to detail and paint the tubes that support the handrail, and eventually I will extend the sidewalk at each end, and weather the concrete. But for now, here's how it looks. Oh, and I used a Dremel to trim off the drain pipe:




I hope to begin painting the building soon.

[Leon]

My jaw just hit the floor.That looks awesome Ray.Just keeps getting better with each update.

[dupes]

Wow, man...all of this stuff is top notch! Great work!

[Ray Dunakin]

Another update!

 

To simulate the look of rolled roofing,  I cut a large Tyvek envelope into strips and glued them to the roof of the building. Then I sealed with acrylic gesso. (This is the stuff used to prime artist's canvas.) I made an access hatch from scraps of PVC foam board, cut away the Tyvek, and glued the hatch in place. I also cut the Tyvek from the spot where the smokejack will be mounted:

 

 

 

The smokejack was made from brass tubes and a block of PVC, sheathed with thin styrene. I also made a vent pipe:

 

 

 

At last, I could move on to painting. I sprayed the structure with a light coat of white primer.

The first thing I would need is a good "concrete" color for the mortar. To me, concrete has always been a tricky color to match. We tend to think of it as being gray, but aged concrete is usually more of a very light brown, often with a slightly greenish tint.

 

To aid in getting the color as accurate as possible, I took a small piece of old concrete to the hardware store and had them scan it on their color matching system. Part of the problem with concrete is that it's not a uniform color, but rather speckled. This can also make it difficult to match with the digital system. The color they came up with was pretty close, but too dark. So I mixed in some white paint. Here's the concrete sample with some of the paint dabbed on at the bottom end:

 

 

 

This looked pretty close so I decided to go with it, and painted the side of the building. I thinned it with water so it would go on thin and not clog up all the texture details I had so laboriously created. On the building, it seemed even darker:

 

 

 

I went ahead and painted a few of the stones, to get a better idea of how it would look. The next morning I took the model outside and photographed it on the concrete patio:

 

 

In this closeup photo, the "concrete" paint seems to match the real concrete pretty well, but as miniature mortar, it just didn't look right to my eye. I also wasn't very happy with the painted stones:

 

 

 

So I added some more white to the "concrete" paint, and brushed it on over the first coat. I had to use a fine-tipped artist's brush to paint the mortar between the painted rocks. When this dried I retouched the rocks, and painted more of the rocks. Here's another closeup shot on the patio. As you can see, the revised paint is lighter than the real concrete, at least in the photo, but to me it works better as miniature mortar:

 

 

 

Here's a closeup of the stones. I found that the key to making them look right is not to use a single, solid color on each rock. They need some variation. And in this case, where there will be a real stone wall next to the model building, it was crucial to match the real rocks as closely as possible. In this shot you can see just how much detail I painted into each stone:

 

 

 

This next photo shows the building temporarily in place on the foundation. Although the real stone wall is in shadow, you can still see how closely I was able to match the look on my painted stone wall:

 

 

 

Here's a closer view:

 

 

 

That's all for now, more later. Enjoy!

 

 

[Leon]

Looks like a perfect match Ray.well done sir.

[deafpanzer]

Great job on the vent... paint on stone wall look pretty good too!