Saturday, January 24, 2015

Lone Rock: A Canyon Country Diorama

The Lone Rock diorama was built to demonstrate rock carving and coloring techniques, and also to serve as a model stand for outdoor photography.


The Lone Rock diorama began with an email from Joey Ricard over at Trackside Scenery. When Joey's not working on his fantastic On30 Spruce Coal & Timber Co. layout, he's producing an awesome series of how-to modeling videos that you can watch over on YouTube. So when Joey asked if I might be interested in contributing to an upcoming video about modeling rocks, I was more than happy to agree. Joey's videos are always fun and informative, focusing on both tried-and-true and new-and-innovative techniques. Just my kind of project.

The idea for a stand-alone diorama that could be taken outdoors for photographing models had been percolating in the back of my mind for some time. Joey's video suggestion was just the push I needed to dust off the idea and get to building. I could document the build with video and photos as I went along, and wind up at the end with the photo-diorama I'd been daydreaming about. I wanted something simple and scenic, with a short length of track and one distinctive rock formation as center of interest. Most of the build is covered in the resulting video (below), so today's post will focus mostly on additional details. Here's how it all went together.

The 12" x 24" diorama started with a simple frame of 1" x 2" MDF and three layers of 1.5" white polystyrene bead-board. Some 1" thick gold polyurethane foam (Balsa Foam) was roughly shaped to form a single, towering butte. 1/2" plywood was cut to shape for track sub-roadbed and glued in place atop the foam. The white foam was shaped with a hot-wire cutter, and a small stone culvert made from Balsa Foam was created to bridge the gully. I used Loctite Power Grab construction adhesive to glue everything together.

The butte was carved from hard density Balsa Foam. This is a commercial version of the same gold urethane carving foam used by Walt Disney Imagineering and Hollywood special effects model builders. It's available through better stocked art and craft dealers.

A short section of the 1/2" plywood sub-roadbed was cut away and a chunk of 1" thick Balsa Foam was used to form a small stone culvert. The arch was created with sandpaper wrapped around a small bottle, and the stones were carved with a hard 5H pencil.

Using photos of rocks from Monument Valley, Moab and Sedona, Lone Rock Butte was carved from Balsa Foam using mostly a #2 hobby knife. The butte was then glued to the base with Loctite Powergrab adhesive. Four bamboo skewers between the butte and the base add additional strength. See the video for more details on the carving process. My part starts at about the 8:40 mark.

Sculptamold was used to blend the butte into the base and to form an embankment along the sub-roadbed right of way. A soft, wet brush is handy for smoothing things out.

Since there would be scenery below it, the stone culvert was finished early and installed flush with the sub-roadbed. It was painted with acrylics and the mortar lines were filled with spackling paste.

Midwest HO scale cork roadbed was glued down with yellow carpenter's glue before just about everything on the diorama was given a base coat of golden-tan flat latex house paint. Then a length of Peco On30 flextrack was cemented in place with Powergrab adhesive.

A wash of diluted India ink was sprayed onto the butte to darken cracks and crevices before final painting was done. Inexpensive craft acrylics were used to complete the paint job. Colors like raw sienna, red oxide, burnt umber and unbleached titanium were applied wet into wet, working from darker to lighter tones. See the video for a more complete rundown on the painting process. Painting and finishing starts at about 12:45 on the video.

The track was painted and weathered using Joey Ricard's easy techniques featured in this video from TracksideScenery.com. First the track is painted flat black. I masked off the diorama for this and did the painting outside with some Krylon spray paint. Next the ties are painted with a light tan acrylic. I used Apple Barrel "Khaki." Then the rails are painted with rust colored chalks suspended in 70% isopropyl alcohol. The final step is to give everything a good dusting with black and dark brown chalks. There's no power going to this track so I didn't bother to clean the paint off of the railhead. On powered track I'd use a Bright Boy or paint thinner to clean the railhead after painting.

The basic ground cover is Polyblend Sanded Grout. I mixed it up with a little water to form a thick paste and then just stippled it on with a cheep paintbrush (don't use a good brush for this! You'll never use it again). The erosion lines were pressed in with a pencil. The grout does a good job of representing soil while also filling and smoothing any remaining gaps in the foam base. This color is called "Sandstone," appropriately enough, and it dries a couple of shades lighter than it goes on. The wet grout generally stays where you put it but I also wet it down with a misting of diluted matte medium to lock it in place.

Once the grout had set overnight, the final coloring was done with light washes of acrylics to blend and unify the grout layer with the rock carving.

Real dirt and rocks were sprinkled on and then glued in place with white glue and diluted matte medium.

The track was ballasted with local sandstone, held in place with diluted matte medium.

Woodland Scenics "Field Grass" was used to make clumps of desert grasses and weeds, held in place with dabs of Aleene's Tacky Glue. Any loose fibers were later cleaned up with a shop vac.

A few more bushes and desert plants finish the diorama. The juniper bushes are Super Trees from Scenic Express covered in Noch dark green foliage. Clumps of gray sage were made with Woodland Scenics medium green bushes, lightly sprayed with gray primer. The prickly-pear cacti are castings from Pegasus Models. Lastly, the 1" x 2" frame was painted flat black to match the fascia on the Thunder Mesa layout.


Building the Lone Rock diorama was a quick, fun and rewarding project. Even if you don't have room for a full layout, I encourage anyone to try their hand at a small diorama like this. It can be finished in a week or so, and it's a great way to learn new techniques or to experiment with scenery ideas. I'll close out today's post with the finished video that Joey and I put together, and with a few photos taken outdoors in beautiful Sedona, AZ.


Set-up for photos in Sedona, AZ.

A small diorama like this is great for photographing models outside in natural light.


That's it for this project. Questions and comments are welcome below. Adios for now, amigos!
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