Railworks America

How does one weather a repaint?? As in Fire damage, rust, and grime

Here's a good start from 3DTrains: http://www.3dtrains.com/guides/painting/

My 1st weathering attempt was not good. But weathering in general isn't so hard. All you need to do is duplicate the layer in the paint program and use the airbrush to spray on the weathering. Once done open layer properties and then adjust the opacity to give it a more realistic feel.

Duplicate the layer? I don't see why.
Don't you mean create a new one?

No that's not what he means.

Not to me... I would 'create' a layer for each effect dirt, rust, soot, etc (not duplicate)