Monday, July 09, 2007

Oil Wash Technique

By Hugh A.

At meetings, I’ve been asked about my process for applying a wash to panel lines on airplanes. My technique is based on a demonstration by Eric, a former BPMS member back in the day when we met at Floyd Bennett in the National Park’s Department building. This description is tailored to airplane applications, but it should be adaptable to most categories of kits. Note that this technique assumes that the model has been gloss-coated with an acrylic paint, as the naphtha in the lighter fluid will not attack acrylic in the amounts used in a wash.

The supplies are simple: artist oils in various shades, lighter fluid, some empty paint bottles, and a calligraphy pen (Figure 1). I purchased the artist oil paints at various art supply or craft stores, selecting shades that complement the usual camouflage colors of grays, greens, browns, and light blue and blue-grey. Ray Umber, Burnt Sienna, and Payne’s Grey are good basic colors that work well on a variety of color schemes. White and black are used to lighten or darken the basic colors. I never use straight black as the effect is too harsh for my tastes. The lighter fluid is left over from the long ago days when I used to smoke cigars, so I can’t say where I would buy it today; perhaps a drug store. The calligraphy pen goes back further than the lighter fluid - to my 8th grade art class (it’s true - modelers never throw anything away that could remotely be useful in the hobby). I would expect that the pens are still available in any art store. I’ve tried a drafting pen, but I find the straight tip of the calligraphy pen provides more control, ensuring that the wash mixture flows down the panel lines and not across the finish of the plane.

Figure 1

As mentioned above, the model should be gloss-coated before using the wash. I use Polly S clear gloss, but any other acrylic should do. Even though the model was probably gloss-coated prior to applying the decals, it’s wise to apply a thin gloss coat over the decals in order to seal them, thus ensuring that the wash will not run under a decal. I found that using the wash after the flat coat made it more difficult to remove wash from unwanted areas.

The process starts with squirting some lighter fluid into a paint bottle, enough to fill the bottle to a depth of approximately three-eighths to half an inch. Add a very, very small dab of the base color - Burnt Sienna, for example - to the lighter fluid and stir. Dip the pin in the mixture and first try it on a paper towel to judge how dark it is. If it appears dark, add more lighter fluid. When applying it to the airplane, apply the wash first to an engraved line representing a control surface hinge line, e.g., the leading edge of an aileron or elevator. These lines are naturally the darker lines on the plane and will tolerate a wash that is too dark. Just touch the pen to the panel line and let the wash flow along the panel line. In 1/72 scale, I feel that I’ve achieved the correct density when I have to look at the other, unwashed surface to determine that there’s a difference. But this is a personal judgment call and you may want a darker effect. I usually do one entire surface, such as an upper wing, than take a piece of old nylon hose and rub off any excess wash that may have pooled alongside a panel line. There will usually be a slight “shadow” remaining where any excess was removed, which if subtle enough, adds to the wash effect. If it proves to be too dark and too stubborn for the cloth, use a pencil eraser to remove the excess. When washing the bottom of an aircraft with light-colored undersurfaces, mix up another wash using something like Payne’s Grey and a lot of white. The model will be a mixture of finish textures by the time you are through, but the flat coat will heal all! Remember, it’s usually a subtle effect you’re after, so err on the side of caution. It’s always better to have to apply another wash than to try and lighten lines that are too dark. Where darker applications are warranted, such as link chutes or engine cowling openings, use a darker mix. Finally, the mix will start to clump in a very short time, so plan on doing the wash in one day or be prepared to mix some more.

[1] The good news is that lighter fluid seems to have a shelf life of forever, based on my personal experience - it’s been twenty years since I smoked cigars.

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