This project was actually fun.
A client sent me 3 factory painted O scale brass PRR hoppers to be weathered.
He included rather specific requests for the different looks he wanted for the 3 cars, along with some very useful colour imagery.
The challenge for me was to replicate the various looks with the mediums I had at hand.
I started by giving all 3 cars an India Ink wash. From there each car was sprayed with different tones of dirty rust colours, varying each car.
Once that dried, out came the artist oils for 2 of the cars. I blotched the sides in a random fashion varying the colour and dirt patterns between the cars and then pulled it together with some more overspray.
The third car wanted that blue/gray steel look from washed away paint. This was the look that I struggled with the most in my mind. It's easy to apply paint, real hard to remove. I made a mask from cardstock and held it off the car side about 1/4" and sprayed a blue/gray mix through it. The mask softened the edge and the thinness of the paint captured the look. The car I worried the most about turned out to be the easiest to do.
I'm always careful with "heavy" weathering. So easy to go too far.