Thanks Tom for the warm welcome.
Well there's no magic I must say. My techniques are probably the same ones most of you's are already using. As far as constructive criticism goes... hard to give when we're all kind of like artists, we may all end up at the same place but we all took a different path to get there... it's great that we can ask each other about different teqhniques and most people I hope, will be oped about it.
So,
I typically start with a model eraser, they come in various grits, and they are really fine some of them. I use them to rub off paint details like graphics on the cars. I think Tamiya makes them. I usually start with a Vallejo acrylic Model Air wash Burnt Umber for rust to start, as I always do. I start with the roof of the car, I just brush the wash around till I see what I like and stop right there.
I will let that set up for a day and hit it again if I want a heavier looking rust effect, again, let it set up for a day. Then I hit the sides. Same thing, same wash again and brush it around (verticle brush strokes always) along panel seams and other details untill I see the ideal effect. Again I let it set up for a day. Again hit the same side depending on the amount of rust I want to see. I do this for the rest of the car's sides and ends.
The next step is to dulcoat the car. Then out comes the oil paints, I mainly use burnt umber, Sienna and black for the next steps. I will also use a piece of sponge ripped out of a large piece of sponge for the light speckling of rust rash and let that set up for a day. I then start to add by brush the burnt umber and sienna oils to the variouse spots of the car.. and let that set up for about an hour. Then I take like fanned brush with some mineral spirits on it (not to saturated) and down brush the ideal spots to simulate the down running rust streaks. The other variuos spots I would really just clean up the edges around the oil spots to give them that sharp rusted patch of medal look just before the rust would start to run down the side of the car, just like that patch of rust below the build date on the lower left side of the Soo car. At that point I would let it set up for a day and hit the remaining sides untill I'm satisfied. I would give it another Dulcoat coat also at that point. Then I hit the model with the powders or pastels.. pretty staight forward with those. You can end it there or give it a light Dulcoat again and have the effect of dust and grime hit by rain like on the Soo car or not by not hitting it with a Dulcoat after the powder work... whatever you fancy. The trucks I will just hit them with a mixture of model air colours of Brown and Tyre Black in the airbrush for a base coat of grime and then apply powders to the frames, the wheels I typically hit them with an enamel rust paint and then add some powders to them. The underside of the car I usually don't bother with, if anything I would just hit that with the airbrush with the brown & black colour.
You know maybe it's just me, but I almost on every car or loco I hit, it's almost like I am always doing things a little differently, maybe that's called progress... or maybe it's just called experimenting. I'm kind of like a non conformist.
I hope this gives you some light into the way I weather things. I'm like everyone else, always learning.
Z