Time to finish off those turrets!
I added some Secret Weapon Armor Wash to the rust mix to make it a bit more translucent. This way I cold make the initial rust/grime streak, and then add some additional lighter orange colors for the final rust effect.
I did that while the first layers were still wet, so that I could get some nice random blending inside the streaks.
A comparison of rust and no rust.
Faded in some areas, more prominent in others.
Last car on the rails!