Working on a 1966 Chevelle SS. Before I bought the car someone had stripped the roof down to bare metal and then shot a primer on it. This was probably done several years ago. Fairly large rust areas were present through the primer. I sanded the primer and rust off the other day and underneath I found the metal is fairly smooth but is stained from the rust. Is the fast etch a good product for this problem, or does the staining indicate the rust is deeper into the metal?
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