Originally Posted by roger1
Re-apply your acid and wire brush the area as many times as it takes to get all the "black" removed.
In heavy pitted areas this may take as many as 20 iterations to get rid of all the rust. If any holes in the metal show up, weld them or fill with lead. Then sand with 80 grit and prime with epoxy primer.
That's right Roger, the only thing you want to prime over is clean shiny bare metal. Those black pits will come back and bite you.