Rusting a Tin Roof

I am currently modeling and weathering a barn.

The kit came with thin metal for the roof. I am looking for a realistic way to add weathering and rust to this roof. The kit suggesting laying on wet paper towels and put in the oven at 150 degrees. I have tried this for several hours with unsatifactory results (I have added water several times keeping the towels saturated).

There must be a good paint or wa***o use on the metal.

Also, what is the best way to glue the metal roof to the cardboard underlay?

Answers much appreciated.

Polly Scale acrylic paint can be thinned with windshield washer fluid ( the blue stuff is what I use) to make a wash which works well. Also pastel chalks or Bragdon Enterprises weathering powders will work. The Bragdon powders are mixed with a dry adhesive so they stick much better than regular pastels.

Have Fun,
Tom Watkins

One technique to try: Apply a light coating of olive oil, and hold it over a flame. Scorch the olive oil (you’ll want to hold the roof material with a hemostat or something) with the flame and wipe off the soot–you’ll have reddish-black oxidation all over the roof.