Weathering Your Model Trains
The art of "weathering" your model trains and scenery is the process of making them distressed-looking or worn. In the interest of making your model trains and scenery more realistic looking, you sometimes need to "weather" them. Having objects look too shiny or new can be very distracting in the overall scene.
Weather with Rust-Colored Paint
For model train cars, you can add the look of rust by lightly brushing on rust-colored paint on the wheels and sides in a rough, random fashion with a dry brush. Use this same technique by adding dark colored paints for oil stains, or more earthy colors for the resemblance of dirt or grime that would naturally occur in a well-worn train.
Weather with Pastel Chalks
If your model train already has a flat finish, you can use artist's pastel chalks to rub in and add a nice weathered effect. After you use chalk powder, make sure to seal the "dust" by spraying on a lacquer finish. If your train has a high gloss finish, and you want to try this technique, first spray it with a clear flat finish.
Get Inspired with Actual Trains
Referencing photos of actual trains can be very helpful when simulating the same wear and tear a train might have. It can also help you reference what colors to use for adding painted worn details.
Don't forget about your scenery. Use some of these same techniques to weather buildings or walls to give them a more realistic feel as well. The art of weathering doesn't take a lot of skill, but it is definitely worth the time and effort it takes to make a model train and its surroundings look just right.