Since returning to the hobby I have come to realize that weathering a model is about much more than making it dirty. Instead, it is a process, with a set of tools, that are designed to bring out the most in a subject. Want to add texture to flat surfaces? Try an oil dot filter!
An oil dot filter is a simple technique that adds thin layers of varying colors over a base coat. Otherwise sterile surfaces now benefit from subtle tonal variation, grime, and streaking effects. Check out the sides-skirts on the Type 90 tank below to see what I'm talking about.
I think it looks pretty cool, and maybe the best part is that it was my first time trying the method. My point is, it's easy! Check out the steps below, and give it a go on your next build.
Surface prep
Modelers are most accustomed to acrylic, enamel, or lacquer-based paints. We often pick one medium and stay there. But many weathering techniques can only be achieved by combining various mediums. Unsurprisingly, this can be a source of confusion for beginners, or at worst, a ruined project.
The thing to keep in mind is that an oil dot filter requires oil thinners. These thinners will react with any previously applied enamel-based paints or effects unless they are protected by an acrylic or lacquer "varnish". A varnish is just a fancy term for a clear coat. I use Pledge Floor Care (yes, the flooring product). There is one other thing: to get the most out of our oil dot filter, we want to use a gloss varnish. Gloss coats dry smooth in comparison to satin or matte coats, and smooth coats make for easier cleanup and greater control over where our oil dot filter pigments eventually settle.
Bottom line: you need a barrier layer to protect your previous hard work from the oil dot filter. Here is a little graphic to make it simple:
Materials needed
A nice feature of the oil dot filter is that you don't need much. If you already have a few models completed and painted, then you most likely have everything except the oil paint and mineral spirits.
Oil paints
Oil-based paint thinners such as mineral spirits
Paper towel
Cocktail stick
Broad paint brush
The technique
True to best practice, I began my oil dot filter on the bottom of my then in-progress Type 90. The first photo is there for a baseline (don't be distracted by the remnants of some other experimentation). The real fun starts in the second photo, followed by panic in the third, and relief by the fourth. Here's how to recreate the emotional roller-coaster for yourself:
Squeeze a very small amount of each oil paint color onto the paper towel. You only need a dab. Let this sit for a few minutes. You want the paper towel to absorb excess oil. If you skip this step the oil dot filter will take an extremely long time to dry.
Take a cocktail stick and place a dot (that's right, the "dot" in oil dot) of your desired colors on the model.
Dip the broad paint brush into your thinners and gently blot the excess on paper towel.
Use the moist brush to wipe away the majority of the oil dots. This will take several passes. Be patient. A downward motion works best for vertical surfaces and a mottling motion works well for horizontal surfaces.
Notice the subtle tonal variation between the first and fourth photo, that's what you are after.
Final thoughts
I will call my first attempt at an oil dot filter a success. The oil dot filter certainly gave the model more depth and texture. And it also made the tank appear more cohesive. That's because there is now a common layer of translucent paint applied over entire model.
It should still be noted that like all things in this hobby, mastery does not come after one successful application. I still need to work out some of the finer points of the filtering process. For example, given certain base colors, what oil colors would look best on top?
Lastly, I'm happy that my tool-set has increased after this adventure. I have never worked with oil paints before: in any context. Now the path is primed to explore a whole host of new techniques. Isn't that half the fun of this hobby?
Thanks for reading,
Mido
Contact the author: mido@igluemodels.com or on IG and Twitter @igluemodels