This article describes a simple jig for painting those parts of the freight and passenger car wheels that ride on the rails, the treads. This applies only to plastic wheels. It is shown using N-scale track and models, but, of course, the technique will work in any scale. The idea is to make the wheels look like metal. In the real world the tops of the rails and the surface of the wheels that touch the tops of rails are shiny because of constant wear. I got this idea from an article in the October 1993 issue of Railroad Model Craftsman, pg 74 by Phil Chiavetta and Frank De Bonis. The jig is nothing but a piece of rail glued to a piece of wood. The parts are shown here in the photo. I marked off with a pencil where the rail is to go and then spread the glue between the pencil marks using the popsicle stick. I placed some weights on the rail until the glue set.
Once the glue was dry, the jig is ready for use. I am using Poly Scale "Stainless Steel" paint.
To use the jig, simply use a small brush and place the paint on the top of the rail. Make the area long enough to cover the full circumference of the wheels to be painted. I did it a few times per wheelset to make sure the wheels were fully painted. After a painting session I clean the rails to make sure the paint doesn't build up over time.
The next photo shows one of the wheelsets of this gondola painted using this method. It is a fast and easy method for adding that extra little detail to these plastic models.
Here is a box car whose wheels have been painted. From this angle they look like metal wheels.