Star Wars AT-ST [WIP - First tentative steps in the use of Oil Dot Filter Weathering Paint Technique]

Before assembly of the Bandai Star Wars 1/48 scale Imperial All Terrain Scout Transport (AT-ST) Walker had even started, there was something I needed to get my head around first. That something is a technique used by scale modelers to increase the richness and variety of hues on an otherwise monotone color scheme, namely the oil dot filter weathering paint technique. Results weren't up to par as I went ahead armed with only a basic knowledge of how to manipulate oil paints in a scale modeling context. Nonetheless I'm posting this in the hope others will learn from my mistakes.

Materials used in my first attempt at oil dot filter weathering

Using an actual model kit as a guinea pig was of course a non-starter. So I got hold of some styrene sheets (Tamiya Pla Plate) and cut out a rectangular piece to serve my purpose. I then went through the usual process of priming it before applying a light gray basecoat i.e. a color I plan to use as the AT-ST's primary hue. The final step prior to the oil dot filter weathering technique is to apply a protective clear coat onto the surface. It was here that I made my first mistake.     

White styrene sheets were first cut out in simple rectangular shapes ...

... before being primed with a fine light gray primer ...

... followed by a basecoat color of Tamiya AS-16 Light Gray USAF and finally a protective clear coat

I had erroneously used a gloss clear coat instead of a satin/semi-gloss or even matt/flat one. It seems a glossy surface is slippery thus making it harder to control the blending process. In my old work flow, I apply a gloss varnish to make the application of decals, pin washes and panel lines easier. So in the future I'll have to tweak this by perhaps adding a layer of semi-gloss after the decals, washes and panel lining in order to prepare the surface for oil dot filter weathering. Some modelers suggest doing oil dot filters before the washes and panel lining while some do it after. I believe the order in which they are done depends on how heavy the oil dot filter blending process is i.e. amount of thinner used.

Oil paint colors used are Winton French Ultramarine, Yellow Ochre, Payne's Gray and Zinc White

As for the paints, I used the Winsor & Newton Winton Oil Colour. Price-wise they fall in the mid-range category and are much more affordable than the scale modeling versions. The actual hues I used from this series of oil paints were French Ultramarine, Yellow Ochre, Payne's Gray and Zinc White. The colors were chosen based roughly on what I've seen other modelers do. Going forward, I'll probably have to refine the color choices I've made here e.g. a buff hue vs pure yellow ochre.

Putting wooden coffee stirrers to good use

But first they had to be cut down to size ...

... before being used to apply the oil paints onto the basecoated surface

It's recommended that the oil paints be placed on a cardboard palette to allow the linseed oil inside to be absorbed out. This has a threefold effect in that the oil paints will then be easier to blend, dry faster and to a matt finish. However, it is likely my subsequent error was to allow the oil paint to dry too much before starting the blending process. I could've also used insufficient thinners when blending or just didn't blend long enough. During the blending process, the oil paints didn't blend very well and the only logical reasons I can think of are the aforementioned ones.   

Initial blending steps looked horrible but that is to be expected

Further blending makes things look better

And yet further blending makes the hues imperceptible ... well that was the plan anyway

For a first try the results aren't too bad but they were far from what I would ideally have preferred. Streaks of paint were still visible in parts at certain angles. The intended effect of the oil dot filter weathering technique is one of subtlety. What I achieved war far from imperceptible. Even then though, the piece looks much more interesting than when left in its original monotone color scheme.

Oil dot filter weathering technique - before blending

Oil dot filter weathering technique - after blending

At certain angles the streaks became less subtle which wasn't what I was aiming for

Since the effort above I've done more research and found two good tutorials of this technique. If you are interested you could check out an article by renowned scale modeler, Michael Rinaldi or a video by Karl Logan for Testors Corporation. Both are great references for the technique, albeit executed in slightly different ways. Depending on whether I have the time, I might still do another test piece or just go ahead and use this technique on an actual AT-ST model kit. Regardless I hope to start working on the AT-ST interior soon. That's next, by the end of this week if I'm lucky. Or the next if I'm not.