The Stovebolt Site Forums The Shop Area Paint and Body Shop phos acid, how should it look when done

Your results are similar to mine when I sprayed it on. I subsequently changed my method to apply with a rag and then wipe off the excess. If I rinsed it according to the directions it left a light coating of rust.

I doubt that any damage has been done but by the looks of it you've got some wire brush/sanding work in your future.

I know that's too late for you but it's always a good idea to do a little experimentation with things like this before diving in.