Sunday, August 8, 2010

20mm Vietnam Riverine Terrain - Part 2 of 3

Part 2 of this project involves a major step forward, sanding and texturing the terrain, but does not display dynamic changes in the photos.

The next step in the process was to sand the terrain. You may want to wear a dust mask, and/or arrange for favorable ventilation, as this step creates very fine dust.

I use an older orbital mini-sander marketed by Black & Decker in the 1980's. The sanding pad is roughly 2"x3" and lends itself very nicely to working with foam. The AC/DC converter pictured below is the original B&D product, while the sander is identical to the B&D version except for that it is labeled as Minicraft from the UK. These models have since been replaced by newer models, including a smaller transformer, and a slightly different sander that used velcro sanding pads. I prefer the older style sander, as the corners of the sanding pads sometimes gouge the foam, a less frequent problem with the older model that has sandpaper wrapped up and over the ends of the sanding pad. Proxxon also makes a similar sander that works well:

I like ths sander almost as much as the original B&D, except that the sanding head is a hard plastic, while the older B&D/Minicraft have a foam pad. Again, there is a tendancy to gouge the foam, so I bought a small piece of rubber from Grainger ( ), attached it with 3M Super 90 spray adhesive (from Lowes, Home Depot, etc), and the sander worked great.

The older B&D/Minicraft model is shown below.

Okay, enough about sanders. Shaping the foam with the surform tool, as mentioned in my previous blog entry, leaves the foam a little rough. I sand it down to a smoother texture, that leaves some divits and pits from the surform tool as shown in the photo below. The tile to the left shows the surform texture, those to the right have been sanded.

Once the foam has been sanded, brush off the foam and clean up the dust. Otherwise, the dust will drive you crazy and create clumps during the painting process. The sanded river terrain is shown below (I know, doesn't look any different than when we started).

I spend some time searching for photos from various sources and comparing river bank textures in Vietnam. The most common texture that I found involved a cracked mud upper bank, with a less dried vertically striated lower portion of the bank.

I had two options for creating the texture. The first was to 'draw" it on and in with a pen or embossing stylus, the second was to use a hotwire type engraver or "pen".

I often texture block and stone patterns into foam by simply drawing it onto and into the foam with a black (usually Papermate because the ink bleeds less than Bic) pen. This leaves an embossed pattern with a light coat of ink. The pen works well as the roller in the tip avoids tearing the foam. The problem is that the ink will bleed into most primers and paints. This can be controlled by sealing the ink with a coat of Testor's Dullcoat before and after priming, though sometimes an extra step of priming the surface with a coat of paint is also needed to cmpletely hide the ink. It is not really a big problem, but adds drying time. And since time is my biggest enemy these days, I opted not to use a pen.

In place a of a pen, you can use an embossing stylus. These are simpy pen-like devices that have a small steel ball (as small as .002") on the end, You simply press the desired pattern into the foam. they are readily available at craft and scrapbooking stores. They allow the greatest and finest control, but are slightly more prone to tear the foam, as the ball does not roll as in the pen. The process is slightly slower with the stylus than the pen, but gives a very nice result.

I opted for the second method, of burning or melting the pattern into the foam with a hot engraving tool. In my case this was an older model from Hotwire Foam Factory:

This does not create as fine a texture as the pen or stylus, but is much faster, and does not tear the foam. It is particularly faster and easier on the irregular surface on the river bank. The pen and stylus would be much more tedious to use in this application, and prone to tearing the still slightly rough and irregularly contoured surface of the foam.

While the actual cracking pattern is much finer than what I produced, I think the modeled terrain gives a reasonable representation of the intended texture.

Most of the work in part 2 of the construction process is now complete. The terrain appears as shown below, not really showing much sign of progress.

The last step is to fill any overly deep pits in the foam with putty, before the finishing process. I like to use light-weight or one-step spackle. It dries a little slower than I like, but will sand evenly with the foam, and is less prone to breaking than conventional spackle. It also readily accepts the artist's acrylic paints that I use, something that regular spackle does not do. The paint will lay on the heavier spackle and dry fine, but will readily tear away from the spackle if scraped or scratched, it does not do this on the light weight spackle forming a much spronger bond.

I simply apply the spackle with my finger (wearing a disposable glove) and wipe it with a damp cloth if needed to smooth it. No sanding is required. The spackle does need to be perfectly smooth with the surrounding foam, it will look fine being a little rough when painted.

The work discussed in this entry took about three more hours, preparing twenty-five and a half square feet of terrain.

The river terrain is now ready for part 3, priming, painting, and flocking. I should have part three up by next Sunday evening at the latest.

Sunday, August 1, 2010

20mm Vietnam Riverine Terrain - Part 1 of 3

Probably the most important part of my 20mm Vietnam project is the riverine terrain. After considering the design for some time, and sketching out some overly complex ideas, I settled on my old method of making modular terrain for my riverine system.

The modular terrain needs to be able to represent everything from large waterways such as the Mekong or Bassac rivers to smaller rivers and rivulettes that are barely passable for PBRs, and also the many canals feeding the rivers with commerce and Viet Cong. Features are to include islands, cutouts for "beaching" sampans, small beaches, streams, foot bridges, and small docks or piers.

The terrain itself will be made from extruded polystyrene foam insulation board, in this case, blue Dow-Corning foam. The one inch thick foam was first cut into tiles measuring 1'x1', 1'x2', and 1'x6" to meet the needs of the design. I cut the foam on a table saw, but it can be cut with a hobby knife and straight-edge as well. The basic panels are set out on my table in the photo below.
The foam only represents the shore line sections of river and a canal farther away and to the left in the photo. The river and canal width will be variable; the water will be separate sections of styrene plastic (not shown in the photo) that set under the edges of the terrain tiles.
Tools needed to cut and shape the foam include two perma-Grit files, one flat and one curved, a hack-saw blade, and Surform tool. While I have hotwire cutters and other gizmos, I prefer these for most of the work. One last tool that was needed was a profile template for the river bank. This template will be used to trace a standard profile on all of the mating edges of the terrain pieces. I cut this template from a scrap piece of plywood, but usually use tempered hardboard.

After studying a number of photos (flickr is your friend), I settled on a profile as shown in the photo above. The height of the bank to the top of the curve in the template is 7/8". The taper extends back to the center, or 6" point of the template. The bevel and curve each extend about a quarter inch into the template. I started work on the foam by tracing the profile onto all of the appropriate edges of the foam tiles.
Once the tracing was done, the next step was to draw the actual edges of the bank onto the tops of the tiles, and cut off the excess with the hack-saw blade. Other features such as the beach and cutout for sampans are drawn on as well. With the excess cut away, the general lines of the river can be seen in the photo above.

Next comes the shaping. Typically, I started at the traced profile edges and cut the edges with the hack-saw blade. I then used a combination of the curved Perma-Grit file and the surform tool to shape the river bank edge along the length of the tile. This is a tedious and messy step, but not really hard. The surform tool is then used the shape the top of the foam tiles and blend the contours into the river bank edges.

Once the tiles are shaped, the tiles appear as depicted above.

Another view showing the river bank a little better. A sampan cutout can be seen on the far bank toward the right center of the photo.
The work shown above took about three hours. The next part of the process (Part 2) will inolve smoothing and sanding the foam, adding more detailed texture to the river bank and prepping the foam for paint.