I am chemically stripping my car and found some spots with bondo. Should I remove all the opld bondo or work wit what I got. Will the chemicals for stripping be a problem with the old bondo and prevent the paint from sticking?

If you are doing as little as just sanding your car down, I would peel all the old bondo out. You never know what is underneith, or even how well the job was done before. Get it out, and start over.

every manual i've ever read states that you should remove old bondo especially any that cracked. another thing to consider is the hardner in bondo will accelerate rust if too much is mixed in.do yourself a favor and get rid of it!

as john said i would take the bondo out, who knows how old, how good or what its covering. Start with a new surface if possible. I personally wouldn't want bondo on my car.

well.....removing old bondo it is. Thanks guys. Not sure why it was there in the first place. the metal looks pretty good. Do you guys use the putty after bondo or is bomdo ok by itself if done right? I agree I dont likebond either, but in my case its a necessary evil. I fixed my bumpers with the MAR HYDE kit a Bondo company I mustsay I am inpressed. Highly flexible, sandable and lppks great cant even tell there was tear there. 100 for used cover or 17 dollars for the repair kit hmmmm. Just thought I would add that in.

I would spend the 100 bux and do it right.

For me Bondo is NEVER an option. I know no one would probably notice. But it might not stand the test of time and I would know that it is there. I think if you go the no bondo route you will definatley be pleased with the final result.

Think of it this way. If you do it right you WILL be pleased with the result. If you do it the cheaper way you MIGHT be pleased with the result. To me this equation is simple.

A friend of mine did some body work on this Alfa Romeo. He did a patch job on the metal and about 3 years later the stuff is cracking and falling out. Now he wasted that effort and must procure the replacement part like he should have done in the first place.

My $0.02.

I disagree; Bondo can last forever if done right. I have spots on my car that I used Bondo on back in 1996 and they're perfect. I also have spots that went to crap because I -thought- I removed all the rust from underneath.

If there's rust underneath the bondo, you need to find some way to completely get rid of it. Just sanding rust away WILL NOT WORK!! Also remember that Bondo isn't waterproof, and neither is regular primer. So after your fill job, and after your primer, either shoot a color coat (of any color!), or spray a sealer or primer/sealer over the area.

Use the spot putty after working with the Bondo. It will fill in any/all pinholes that are left in the bondo after you sand it smooth. Work it over the bondo with the same spreader you used for the Bondo... lay a lot on. When you sand it off, wear a dust mask- it'll create a lot of fine dust that you don't want to breathe in. (It turned my white socks pink!)

I've always used "Ultimate Bondo", in a sky-blue colored can. The filler itself is white, and the catalyst is blue. I have no complaints with it.

Remember that for a good filler job, you must use the absolute minimum amount of filler. Using more then a 1/16th inch is pushing it!! The surface must be down to the metal, roughed up with 40 or 60 grit paper, be absolutely clean (use a prep solvent first), and have no rust on it. If the dent is too deep, buy a body hammer and dolly and work the dent out so it's a shallow dent (like a door ding from a parking lot). If you use a slide hammer, you must weld those holes closed; don't just lay bondo over a hole; that's just asking for rust. And remember to shoot a galvanizing compound over the "back" of the holes you drilled for the slide hammer.

After you think your filler job is perfect, spray a "guide coat". This is a contrasting primer (I use black primer for the guide coat) that you spray over your regular primer- don't spray too much, just "mist" the guide coat over the repair. Then get a long board sander (NOT YOUR HAND! Never use your hand- you'll groove the repair surface!!) and sand over the area using left-to-right/up-to-down motion- and then reversing- right-to-left/up-to-down. Make an "x" as you sand. Always lift the board sander off the car after every stroke. What will happen: You'll sand away the guide coat. Where the guide coat remains is a "low spot" that needs additional filler. Where the guide coat AND regular primer gets wiped out to expose filler, that's a high spot that needs to be taken down.

Practice by buying a piece of sheet metal from Home Depot's hardware aisle. Kick it a few times. Then use the body hammer & dolly to work the dent out, then lay your filler over the area and make the panel smooth again.

REMEMBER: NO RUST!!! If you find rust you better get rid of it, and not just by sanding.

Also- the top of the roof, between the back of the door window and the front of the hatch window, is a body seam. GM filled that area with lead. If you find it during your sanding, leave it alone... don't breathe that in, it's not Bondo, it's from the factory. Unfortunately I had been sanding that away (until I realized there was too much of it, and stopped sanding) without a dust mask... yikes. Nothing like some lead in your diet, eh? Yep, now I use a dust mask for everything.... especially fiberglass- our lungs collect fiberglass, we'll never cough it out.

I've used that flexible bumper repair kit before (2-part adhesive, right?), it works great. It's just what a body shop uses. Remember if you're fixing a tear, and you don't want it to tear again, you might want to reinforce the rear of the tear (inside of bumper cover) with a small piece of fiberglass.

[edit] Oh what the hell, I have some time to kill. Everyone is scared of Bondo... it's so bad, it's crap, etc. Guess what... before Bondo, lead had that same description attached to it. Yep, people used to use lead to fill in dents. In fact, you'll hear some restoration guys say "Don't use Bondo! Do it right- use Lead!" People used to say "Don't use lead!" because of those guys that used Lead improperly. Too much lead, improper surface prep, etc would make the lead fall out. Know why Bondo got it's bad rep so fast? Because suddenly, you didn't need any specialized tools or equipment to work with bondo! All you needed was a $5 can of Bondo and some sandpaper and you were a body man! So if a million people used it and 800,000 used it wrong and 800,000 were unhappy, guess what, Bondo is called "bad". Just like the TH-350 transmission... used to be so unreliable that people got rid of the 3-speed auto and dumped in "bulletproof" Powerglides. Kinda reminds ya of us, eh? Getting rid of 700r4's for TH350's? Okay, history lesson over

exactly as the man said,sand with a long board,block sand and keep filler thickness to absolute minimum.kill all rust,amen brother!:rockon:

I completely agree with Tom. Sometimes you simply MUST use filler to cover imperfections. Or what about if you are doing some really custom work where you have to use polyester filler?

Filler when mixed and applied as Tom has indicated can come out great.

I have used evercoat's RAGE filler, that stuff is even better then bondo I find. Great sandability and cuts job time down for you.

Make sure you do remove all the bondo on your bodywork. If you are using a chemical stripper, then it will soak into the filler and ruin the surface.