So this Is what you will end up with!
The idea is to get a good base metal layer. You will need an airbrush for this but don't let that put you off. Give it a go with a regular brush and it would be great to see how that works in the comments.
So phase one. A few different layers of silver, and dots of purple, yellow and brown to indicate heat damage. Thus the flaking paint.
Remember this is what will be revealed once the paint has pealed.
Next is a couple of thin layers of purity seal. You want this layer set in stone.
Then a few layers of regular hair spray. Any drugs store sells this. Regular strength. And just spray it on.
Once it's dry the fun begins. Airbrush your next layer on. Then using water on a clean brush, lightly brush away the paint on the areas you want distressed!
The next step is using thinned burnt umber oil paint to give it the rusty look.