Module Construction

Posted on June 7th, 2010, by Mike

My N-Trak module, representing an interchange between two railroads, incorporates some of my not-quite-conventional modeling techniques. These under-construction photos show a little bit of what is “under the hood”, so to speak.

Scenery layers

This first photo shows the base layers for my scenery, as well as the unballasted track. Notice that I used HO-scale cork subroadbed (one half strip per track) rather than what is commonly marketed as N-scale, because the half strip of HO is both narrower and taller, producing a more elevated mainline. Of course, locating the cork and track is a bit more complicated, since you’re not butting up to a track centerline but rather to an offset from that centerline. But I really need the extra height since my scenery includes a “soil” layer, which will bury the edge of the cork.

The “soil” layer is a varying thickness of my home-brewed concoction of papier-mache and joint compound, to which I add various color and texture agents. The goal is to produce something with a natural grey-brown color throughout, so that any damage just reveals bare earth and not raw white plaster. I use tempera paints for color, both because they are cheap and also because they do not cure but rather can be re-wet; this means my finished scenery can be reshaped just by soaking it again. This soil layer, when first applied and while still wet, gets some sand or dirt sprinkled onto it so that the very top is, in fact, “soil”. I first developed this soil-layer plaster mix when I was renting an apartment and had no place where I could get “messy” – I needed a plaster mix that I could whip up in small batches and that would be more readily controlled than conventional hydrocal. I apply it with a plastic spoon, which I use as a sort of trowel and sculpting tool.

Under the soil, though, is my favorite discovery – expanding foam! I use “Great Stuff” which comes in spray cans at your local hardware store; it is sold as a way to insulate the small cavities around doors and windows. Its long straw-like nozzle permits relatively fine control, and I’ve developed a touch for squirting out just as much as needed for a given feature. Of course, it expands a lot as it cures, an imprecise process no matter what. But the imprecision results in what painter Bob Ross liked to call “happy accidents”; the scenery takes on random forms, and if I like what I see I can keep it. If I don’t, then an old steak knife makes short work of carving it to the contours I really intend. The lumpiness provides a form of mechanical keying for the soil layer, since that plaster mix has no real adherence to the foam. After many years of taking this module to shows, and all the wear and tear that implies, I have not had any issue of delamination of the soil from the foam. The papier-mache affords the benefit of being slightly flexible, hence must less prone to crack under the stresses of portability.

Module under construction

Every surface that is to receive greenery is first treated with the soil layer, so all the bare plywood seen in these shots will later be covered. The grass will not need to hide every square millimeter; in fact it may be better to leave some of the brown soil showing. However, as I am modeling the verdant north of Virginia, I ended up with some rather thick grass and very little of the brown now shows.

You can also see that I painted my track, prior to moving on with scenery. I used a simple technique, with two cans of spray paint. The first was a brown primer, roughly rust-brown in color, and the second was anodized bronze, a darker brown. All it takes is a low-angle pass with the rust/primer color, to get the sides of the rails painted, followed by a top-down spray of the bronze to hit the tops of ties but not the rail sides. Of course, wipe down the top of the railhead immediately after each spray, and you should be sure to mask the critical areas of turnouts beforehand.

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