I have used phosphoric acid in a spray bottle on large areas, doing about a 3'x3' section at a time. Just spray it on, let it sit a few minutes, wipe it down and then hit it with a wire brush on a side grinder. What it does is soften the rust and the wire brush will remove what is loose. Lather rinse and repeat (do it again). It will usually take five or six applications. The last few times you are down to where it looks like shinny metal, but when you spray it the rust in the pits will turn black and show up well. Keep doing it until when you spray it there is no black in the pits. Then do it one more time and rinse like the directions say. I redid most of the body panels on my 60' MGA that way, before I had a sandblaster. That was fifteen years or so ago and I haven't had any rust problems so far. Use a mask.
Last edited by neilroy; 02/25/2009 1:35 AM.
