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Discussion Starter #1
A quick question for you body experts, recently my wife ran my 70 maverick into the ditch,
(no damage except to the splash pan which was pretty mangled)after a full day of grinding all the paint off,hammering, i got the pan pretty straight. but will take minimum body filler.
anyways, a little bit of bondo(two coats spread real thin and sanded down nicely)the splash pan looked great, ready for primer. Fast forward to the weekend, yesterday i sprayed a light coat of epoxy primer and walked away. this morning i went out to block sand said primer to find out that everywhere there was bondo(not much but several places) the primer had bubbled up the bondo(looked like the same reaction you get spraying lacquer over enamel) this was all the way through the bondo(to the metal) had to grind it all out to start over.any ideas, where did i screw up?i used a new can of bondo brand filler and a quality primer, i just don't want to repeat the process.im not a body man, but i have always managed to bungle my way through some pretty decent paint jobs. any help appreciated .(i have a water separator on my compressor and a disposable filter on the gun)
 

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Take it all off down to the metal again. DA the metal with 120 grit and then spray one medium wet coat of epoxy primer. Let it dry over night or focre dry it after a 15 minute flash period with an ultraviolet light if you have. Direct sunlight works good too.
Then make sure you stir the bondo in the can. You want to go in an up/down circular motion to thoroughly mix the resin that sinks to the bottom of the can and avoid making air bubbles.
When you mix with the red cream hardener be sure to not use too much hardener. When properly mixed the filler should have a light pink color and be uniform, no streaks of red or gray.
Don't load in onto your panel. Spread it on as eavenly as possible allowing more in the low spots and less on the higher spots. When it's just about cured, 15-20 minutes based on temps, use a half-round surform file (chessegrater) to shape it where it looks even and just needs sanding. If you see low spots, brush off all the loose shaved filler, blow with compressed air, pop any air bubbles you see and blow them out thoroughly. Skin the entire area again and repeat. After you're satisified that it's filled in even, sand with 80 grit on a long board or block in an "X" motion. If that looks to be all you need, go over it again with 150-180. After this I would skim the entire area with a polyester putty. This will be white glazing putty with blue hardener. Again when properly mixed it will have a uniform pale blue color. These puttys are "self-leveling" so get it on smooth and let it dry for 1/2 hr-45 minuntes then sand with the same long board and 180-220 grit. Make sure eveything is dust free and prime again with the epoxy. One medium wet coat. Allow that to dry at least an hour and then spray 2-3 medium wet coats of a good 2K high-build primer. Allow that to dry overnight or force it the same as above after giving it a 15 minute flash time. Wet sand with a block and 400 or 500 wet paper in the same "X" pattern. Then clean, use a de-greaser/wax remover and apply base followed by clear. Unless you're shooting single stage then no clear.
 

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Discussion Starter #3
thanks, i just shot another coat of epoxy primer, tomorrow evening i will deal with the body work, (i knew bondo could be put on top of epoxy primer and thats probably the way to do it, but it just seems wrong to put anything under the bondo :) when i was coming up we didn't have all this new fangled stuff, we just used lacquer primer and enamel, and anything but metal under the bondo was a huge no no(i try to stay away from bondo period, my maverick until now was body filler free,but straight splash panels are rare as can be)we will see how it goes this round :beer:
 

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Yeah me too! Started in '78 out of high school. Anyway, today's bondo is better than what it was before 3M bought it out. It used to be a real heavy talc based cheap filler. Personally, I prefer evercoat's Z-Grip, it's a nice easy to sand lightweight filler with great adhesion to bare or galvanized metal.
 

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Many different schools of thought On materials & methods to do bodywork,different ones aren't necessarily bad. Epoxy first to base metal is the time proven old school method forquality work,personally haven't done it hat way althuogh I highly agree with it.Most quality fillers, such as almost any evercoat type I,ve used in the last 25 years has product in it to prevent corrosion when used on clean rust free metal as well as stick to any properly scuffed cured paint surfaces.Most of todays paint shops then use 2k primer on top of filler before final sand &paint. Not as good as epoxy first, but good enough for shops to warranty.
Personally for any auto body work , I stay away from possibly old auto body parts store (bondo) & get quality evercoat filler which is constantly turned over from real paint shops. I only use BONDO brand for wood repair & such at work.Like the Z-grip Bobby mentioned for base metal work ,Rage extreme for general minor filling , & metal glaze for all final sanding, so less 2-k primer which shrinks more than filler gets used. Also like usc all metal for base coat on rougher repairs.
I have heard of certain problems from certain brands of epoxys, I think mainly lifting under paint. True expert full time bodymen generally stick with products they know & may not know about some potential problems with certain brands. A google search on your brand may bring up posts if there has been an actual product problem.
 
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