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You are watching: How to remove bondo from car


Working on the cowl cover. It looked to be in real good shape. I started hitting it with the DA to knock off the old cracked paint, and ran into multiple layers of old, hard paint and then I hit the large patches of bondo.There is not any rust to be found on this cowl panel. Apparantly is has some hella-huge dents on both ends, adjacent to the fender.I need to strip it down to bare metal to do some hammer & dollie work and minize the bondo usage.What is the best chemical (name brand, type, etc...) for removing old, hard paint...? is there something that will eat the bondo away too...? I dont want to have to sand all of that crap out of there.Need recommendations....-thanks
Jeremy,I used some Aircraft Stripper from O"Reilly (the big ole jug of it) on the hood and it worked pretty well. It seemed to have some trouble with certain layers of paint, and I ended up applying and scraping several times. Even then, I still had to do quite a bit of sanding. It will soften the top of the bondo, but if it"s big chunks there"s no other way than to grab the dust mask, goggles and go to work with the DA.I honestly think they don"t make anything stronger due to safety regulations.My $.02 - hopefully others have found better products.Eric

yea, I have been calling around to some different autobody paint supply stores. they all recommended the air craft stripper also. One guy said it would severly "goo up" existing bondo, others did not know what it would do to it... I will find out this weekend! :biggrin:
Aircraft stripper doesn"t work too well on thick layers of bondo....But a wire brush wheel works wonders....just don"t let it heat up. In fact, that"s how I warped my
-Chris"65 "vert restored, "65 coupe driver, "65 "vert project, "01 GT Bullittmy website (currently unavailable)

Yup, airplane stripper is the stuff. It will lift thin coats of bondo like paint. But if the bondo is thick (>1/8") it will just make it soft and you will have to scrap it out and apply multiple coats.
"If I can"t fix it, I"ll fix it so no one can !"1969 Mustang LE600 Sportsroof - Groovy Green1969 Mustang LE600 Coupe - Flower Power Red1969 Mustang Sportsroof - Dark Jade1969 Firebird 350 Conv - Mayfair Maze1968 Cougar Hertz XR7-G (project)1959 Oldsmobile Super 881963 Jaguar XKE Coupe (project)
sometimes a rap on the bondo with a hammer and chisel will crack the bondo, allowing you to pry big chunks off while retaining sanding for the leftover remnants. Is cleaner and quicker. Aint it great having a removable cowl cover!!!

I"ve tried a lot of chemical strippers and they"ve all been a waste of time/money including the aircraft stripper. Wire wheel is the best way to go. The only use for chemical stripper i"ve had was on stainless trim, chrome, ect... old paint on these pieces comes off well without having to worry about scratching the surface of the shiney parts.

I stopped by an auto restorer shop not to long ago to ask this same question, and they told me that all of their cars are stripped with aircraft stripper.
1967 mustang GTA coupe. I got this car in 1987 drove from 88 to 95 off and on and then I parked it. curently known as scrogg67
Hydrochloric acid is not a good choice. It is strong pool acid. Pool acid will not eat plastic, hence the plastic containers. It is water soluble, water will dilute it, which tells us that it will not eat plastic. Besides, it is nasty stuff and gives off bad fumes.

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I stripped my trunk lid and the cowl with a high quality 1 inch wide straight edged putty knife, wire brush and aircraft stripper. If you start the putty knife in an area where it"s pretty much down to bare metal, then tilt the putty knife back pushing the knife firmly forward. It can usually get under the heavy coats of paint... just be careful though, the paint chips come flying up in small pieces. This worked especially well on the top layers of paint. After that scuff the remaining paint / primer with sandpaper, and then apply the aircraft stripper. In my case it took a while to loosen up the primer coat, but it eventually loosened up enough to scape and sand off the remainder. It took me all of a 1/2 hour or so to scrape the trunk lid down to the primer. It took a bit longer to clean up the primer layer where the stripper had a tougher time.. If you try the putty knife, just be sure it has a nice edge on it, a worn one will just slip..>"68 Highland Green fastback clone. 331 EFI, AFR heads, tube chassis, Cobra brakes, Fox rack & pinion steering,T5z, 8.8" Auburn limited slip w/ 3.27:1 rear gears, triangulated 4 link, QA1 coil overs, run once in the 1/4: 13.3