Today in weathering I'll be explaining the Oil Technique. I stumbled across this on military modeler forums and monthly magazines. Apparently it's a well known tool in the military modelers tool box. As a wargamer I have never heard of this or seen anyone use this. I've recently learned this little trick and after I learned it I started seeing it pop up more and more. A lot of golden daemon winners use this one.
This technique adds a couple of steps to the model painting process, but if your looking for some very subtle changes or coloration of your model that will go miles in realism this is defiantly it. First do all your base colorings and mostly paint the model how you want, including washes and highlights and everything else. Then you'll need to clear coat your model in a GLOSS clear coat. This will make it so the oils and turpentine or thinner will flow easily and not mess up any previous paint work.
After your model is clear coated in a gloss you'll get out your oils. For this weathering on my Gundam model I used White, Black, Yellow Ocher, and Burnt Umber. These are traditional artist paints that an artist would make an oil painting with. You can find them in any craft or art supply store. Because of what we're using them for you will not need a big tube and this stuff lasts a long time before going bad. A tube will range from 2.50 to 10.00 depending on brand name and quality. You will not need a high quality paint for what you'll be doing with it. Next you'll need a turpentine. I recommend turpenoid. It is an odorless turpentine that does the job just as good and won't kill the few brain cells us hobbyists have left.
To use this technique you simply add a tiny dot using a small paint brush or a toothpick to a spot. (try and put it on the edge of a panel or edge of the model, anyplace grime or stains would accumulate) Next you'll get a clean brush and dip it in turpentine and drag the dot of paint out in a line. This will thin the paint down considerable. It makes a very transparent layer of paint in the hue of the color you dotted the area with. (about 10% opacity) This will add color and interest to an otherwise flat panel. On the Gundam The legs are white I added the burnt umber and yellow ocher in spots to look like oil stains or dirt left over from rain on the otherwise solid white areas. This kept the legs 'white' while adding a very subtle change in hue to make it not look 1 dimensional or flat. I used the white to brighten up spots here and there that got too dark. I lastly used the black under vents and thrusters to represent the soot or burnt spots in the paint where gases were vented. After you weather on top of the gloss you'll wait for the paint to dry and clear coat back over the whole things in a flat clear. This will bring everything thing back into one piece.