Question: How can I make my track dirty? Everyone seems to use an airbrush but I don't own one. Dave. Leicester
Phil: An airbrush is a really handy tool for any modeller, but it's rarely the only way to achieve what you are looking for. I suspect that having splashed out on one, modellers look for as many uses for it as possible.
I'm not a fan of airbrushing track simply because of the fumes produced. If you build your layout in a shed, then shutting the doors and walking away when you have finished to let the smell die down may be fine. If you build your layouts in the house, the rest of the family might not be so forgiving!
To model dirty track, I start by painting the rails and sleepers with either Humbrol or Railmatch "Track colour". It's a nice dirty brown that on its own will make your rail sides look smaller. Don't forget to clean the top of the rail by rubbing a bit of wood along it while the paint is still soft, and then with a track rubber once it's dried.
Then, I ballast the track. Dust from whatever you are using will stick to the track, subtly altering the tones and removing the "all one colour" effect.
Once the ballast is dry, and it's really important to let things dry fully between each stage, try some washes of dirty brown and black paints. Where locos, especially diesels stand, there needs to be plenty of black grot, they do tend to drop oil.
Finally, and this makes the biggest difference, brush weathering powders on the track. You'll need to really scrub them into the ballast, but once there, they aren't going anywhere. I use brown, black and grey with bits of rust (don't worry about the name of the colour, it's just redish-brown) everywhere. If modelling an engine shed where you find mountains of ash, I'll mainly use grey or black around the coaling area.
Don't go too mad with all this. Running lines are usually pretty clean, the linesmen kept them this way. Look at prototype photos and track at preserved railways for inspiration and gradually build the effects up.
If you have a model-railway question - e-mail Phil and we'll try to answer it here.