Rain marks, oil spills & rust
Rain marks are vertical dirt streaks on armor panels created by rain or gravity. I think it's the best effect to create a sense of scale for a mecha, so I do it religiously despite the work involved. The same techniques can be used for oil leaks and rust.
|With the blending technique on the oil page, you can settle a little oil paint on the spot where you want to start the streak. Ivory black or grey works pretty well. Again this blending is easier with flat surfaces.|
|For rust, ivory black mixed with mars brown works pretty well. Rust deposits quite a bit at its origin and gets washed down by gravity or rain, so more oil at the origin. It's not quite done here, more blending is needed to fade out the rusted area a bit more.|
|The NT-1's marks are all created with this method. It's a little tedious but I think it was worth it. It makes the robot look more detailed and more in scale.|
I tried another method on Ez8, this time using the sand paper again. I sprayed a thin layer of smoke on top of the painted surface, so the Ez8 looks a big dark. Then I took a worn out 600 grit sand paper and lightly sand away the smoke paint from the center of the armor panels, using a series of vertical parallel strokes. As a result, the left over smoke paints became rain marks, and the amor panels looks quite realistic.
The pro of this method is that it's faster than the method above and is less frustrating. The con is that it's again hard to control sometimes, especially on complex curves. On the Ez8, I fared pretty well with the areas shown here. However on the more complex and curvy leg areas, I didn't do so well because the amount of paint removed by sanding is uneven when the surface is not flat.