I've read about but never used the salt weathering technique so I decided to give it aa bash on my cardboard models to see if they could stand up to it.
I used a set of the converted shipping containers
as well as a model that is still under development (a South African mine protected vehicle called a Casspir).
Both these models are made from 1mm cardboard.
I tried two different undercoats: the Casspir got matt varnish spray paint and the containers got matt black spray paint.
Both models were then sprayed with Tamiya Hull Red acrylic.
Then I wet parts of them with warm water using a paint brush and sprinkled coarse salt on.
I let that dry overnight and then gave them a few coats with the airbrush. The horrible yellow and blue paint scheme on the Casspir is the old South African police livery.
I then just scrubbed off the salt with a dry brush and it looked great!
When I do it next time I will vary the undercoat a little.. bits of orange and brown splotches will make it a lot more interesting visually.
Of course, I really overdid it on these models, particularly the Casspir as this is a wrecked vehicle. For a vehicle in use more restraint is indicated.
There are more WIP
and finished shots here: http://nothingunpainted.blogspot.com/