Had good results with International etch primer on our props over the last 5 years. Always turned the right shade of brown / orange, to confirm good etch.
See the <A target="_blank" HREF=http://www.yachtpaint.com> International </A> website for more details.
Guess your too late.....you should apply primer the second the blasting has fibished....the corrosion I guess has already started and you will only be sealing it in!!!