[Orange97GTVert]

Bondo will not fix rust problems. In fact, bondo will seal in moisture and the rust will spread and the bondo will come out. Bondo is for filling dents, and used properly is good.

To get rid of rust, first you have to clean the area thoroughly, I use a wire brush on a drill. Get it really clean then neutralize it. There are several products available that will neutralize rust. I use a spray on product that sprays like clear paint and turns to a black primer. It seals the area so you can repair it.

If the rust has eaten a hole in the metal, it is best to cut it all out and weld in a patch. If it is small, you can make a small dent around the hole, cut a patch out of sheetmetal. Mix 2 parts of J. B. Weld and cover the area, then place the patch in and put more J. B. Weld around the edges of the patch and let it cure for 24 hours. Then you can sand it and fill the small dent with bondo, then prime and paint. (This is a good way to fill trim holes, too. Just make sure the dent is large enough that the patch is below the surface so the bondo completely covers it.) Welding is better, but most of us don't have welders handy, and some of us who do aren't very good with them (me).

The same goes for fiberglass, you can't fix rust with fiberglass, the rust spreads and then the patch cracks and pulls out. My 65 Coupe was repaired that way, fiberglass and bondo, and it was a mess, I had to replace both quarter panels because someone took the easy way out.

Finally, bondo will cure in cold weather, but the curing time is longer than when it is warm, so don't get in a hurry. Hope this helps.