Rusty

The Twelve by Twelve group's current color challenge is a palette of rust colors with blue patina-like colors.  I've been thinking about what to do to "play-along" and I think the obvious thought is to try to "rust" some fabric. I'm sure some of the twelves might try that.  I've been wanting to try it for a while now.  But when I read some info. about the process on the internet, there was one place that said the fabric would keep rusting even after you had neutralized it.  You would need to neutralize again every so often (maybe in a year?). 

I still want to try it, but it doesn't seem very archival.  Maybe if it was coated with acrylic medium afterward, it would be sealed enough so that oxygen wouldn't get to it and continue that rusting process.  Any thoughts on that?

I will look through my fabrics and see what I already have that is rusty colored.  I may have to do some painting or rubbing or something.  Inspiration for this challenge could come from looking at rusty objects.  But I have some inspiration from our trip to Yellowstone last year.

What other things in nature can you think of that have rusty and blue colors?  I would like to read your ideas.