More updates. After several layers of rust and dust colors with pigments, washes and streaks, here are the results.It needs some grime at the lower spots, mat varnish again and it's ready.

Rusting second attempt....

Some update here.I added spots of rust with the sponge technique and with a fine paintbrush.
Sometimes I find myself goin' very far away and overdoin' things....

Then I drybrushed light oil colors to break the contrast and added a couple of

handmade custom graffiti...

So, the next steps will be dust, rust and dust streaks and of course grime all over.

Maybe some lighter rust colors would be more than welcome.

1st attempt...total failure....

...so after a light misting with my airbrush with very diluted acrylic light grey and low pressure, I managed to fade the blue color. At that point I rushed the things and without waiting - only for half an hour - I tried to duplicate the 1st layer of rust. For this task, I used the old, good burnt sienna artist's oil color. Then the disaster stroke me......

 It 's OK I said to myself. Next time be patient, my young padawan.....:)  Let's reset the whole thing.

The image below shows how the car looked after highlighting the upper surfaces of the panels by drybrushing with lighter oil colors and applying dark washes.I also added a handmade graffiti....

To be continued...

Here I am, with a nice lifelike N scale (1/160) boxcar in blue color. At first I wanted to add it in a post-apocalyptic diorama, based on the "The Book of Eli" movie, where everything is burned and rusting away after a nuclear holocaust. So I wanted my model to look as if it 's standing there for more than 30 years under the acid rain and the dusty winds. Bellow, 2 screenshots from the movie.....

So the boxcar looked like that when I bought it....

Time to wipe out this shiny blue color and to extract the nature of the rusted and rotten metal....