I primed the whole thing white, then put the blue on top, however when I got to the bottom part i added more water into the blue so it became more of a wash. I had to keep my painting quite up and down so it looked as if the submarine had scraped its way up the shore.
I found the rusty part shoed up better if I painted a little white patch on top of the blue where I knew I wanted to rust. I then took my raw sienna that I used for the other rust projects and painted it on quite washy, letting it drip down every so often.
Then same again as last time- iron powder, vinegar= rust.
to add a little more texture i took a chisel every so often and scraped into the blue paint to keep with the scratchy washed up texture...