Loco weathering

[NYSW F45]

Im going to attempt a weathering of one of my loco's. Not any of the newer ones but one of my older ones. I just want to make it look dirty/grimy. I bought barmills weathering powders that has grimy black, light/medium/dark rust.

Can anyone give me some advice to just make it look used and abused so to say.

Oh and i'll post pics later of a proto 1000 Conrail box car that i weathered. I think it came out soso. Used white oil pastels mixed with some of the grimey black powder and a little bit of thinner. Brushed it on, worked it in and wiped it off. Then painted the trucks and wheels to give them a rusted appearence.

 

[UP2CSX]

How "grimy" depends on the railroad. A well used UP engine usually showed some fading of paint and lettering and some black rain streaks down the side form the exhaust. OTOH, GM&O engines always looked like they had a team that threw dirt on the engines at every stop. I'd first start with the roof and give that the grimiest black look from all the exhaust. I'd then work my way down the sides with black steaks from the exhaust residue. I think you need some kind of color that more or less matches the lettering so you can fade that out too.

Rust is a little tricky. There are not too many Class 1 railroads that let their uints get very rusty. It is common to see rust on the trucks and underframe but about the only other place you would see rust would be places like engine access hinges and the pilot areas of the engine. My advice woud be to start with the engine looking lightly weathered and post a picture. If that looks good, then it's realy a matter of darkening (or lightening) up those lightly weathered areas so they look like the engine hasn't seen a paint shop or wash rack for a while. It's easy to go overboard and create a real rustbucket. You see that sometimes with freight cars but locomotives usually never got anywhere near that bad.

 

[Boilerbuster]

I have a UP Dash 8 that i gave a thin coat of black all over the engine. I used a brush to simulate streaking down from top to bottom. I also by mistake but like the turn out used thinner to thin out the black and it faded the yellow and got some paint flaking in some small spots that look great.
Remember fuel streaks at the fuel cap on the tanks as well. On Ligher engines I try to make them a little darker with grime as well as fading paint. Darker engines just try to fade and put some hard water stains on them. Unless like some Southern pacific engines that I have seen covered with heavy grime