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Old 12-01-2002, 12:10 AM
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Post How long does it take thin amounts of bondo to crack?

yeah just because people are pissing me off with their horror stories about bondo I was wondering... how long does it take for bondo that is at the most 1/4 inch thick in small areas and mostly 1/8 thick in the rest of the areas to crack??? See thing is I pulled all the dents on my car (no money for new panels) and I got the metal as close as possible and then just used the bondo to smooth it out... the guy who helped me has done dents like this since he was 16 and has no problems... he even has a vw beetle that he had in collage (good milage, his mustang was his toy) with 1/2 inch thick bondo and it didn't even crack.. So if there are people having no problems with it why the hell does everyone think bondo cracks so fricken easy?

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Old 12-01-2002, 04:34 AM
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Cool

If the mud is laid on properly, metal clean and ready to accept the mud it will last a very long time. Dirty metal, not scratched for adhesion will crack sooner. Some people even put tiny dents in the metal to be skinned. Old timer swear by it and some hate it. A lot of CUSTOMS have a lot of mud in them. Metal work is a fine art and there arn't many people ready to PAY them what they are worth, so mud to the rescue. When/if it does crack fix it right away, leaving a little crack will cause big trouble later.

Todd
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Old 12-01-2002, 12:38 PM
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Hey Stoned,
If done properly it should last indefinately. DO NOT use the Bondo brand that is sold in Wally Worlds, Advanced Auto, and the other cheapo places. Use a good brand of filler like AllMetal or (can't remember the name but HK has mentioned it a few times. Starts with E) and it should last for a very, very, long while. MIX ACCORDING TO DIRECTIONS. Too much hardener, or too little hardener will affect it and chances are it will crack out. Also the thinner the better. If someone puts it on a 1/2" thick they should have replaced the panel more than likely. Of course I have seen it on some cars that was thicker than that. Also when using something like AllMetal, make sure the metal you are applying it to has some teeth to it and is clean. Use a coarse disc (coarser the better) and grind the area that the filler is to be applied to. Spread a thin coat and use a cheesegrater type of file to rough the filler in before it completely dries. Add another thin coat if needed and sand smooth and prime and you should be good to go. This is the basics. Just be sure to read all directions. Evercoat is the other brand name I was trying to think of. Had a senior moment there.

Kevin
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Old 12-01-2002, 05:02 PM
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Evercoat would be a reputable brand also.
Later,
WEIMER
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Old 12-01-2002, 08:11 PM
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I have two cars that I bondoed 25 years ago and there is no sign of cracking on either one.

I bought a hot rod at a good price that had cracked bondo all over it that was less than two years old. What was the difference?

On the hot rod there were places all over the car where two different pieces of metel would come together and almost touch. Bondo was used to join the gap. In time this fails. You either have to weld or fiberglass the two pieces together before you apply the bondo. Another problem is if you have a hole in metel, you are supposed to have a backing for the bondo. Some people will just slap it in there, and again you will have trouble with this later on.

I have found the best results using the fiberglass impregnated bondo, with a skim coat of two part glazing putty on top of that. Then spray with epoxy primer, then hi solids primer, block sanding with each step. I have never had a blead thru, crack, or failure using this method.
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Old 12-01-2002, 08:50 PM
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I don't know what kind of filler I used... (guy I know who teaches me how to do stuff had a bunch) Anyway what we did was we took the angle grinder to the metal... it is really course... also we always made sure to get the metal as close as possible, except for the doors because they are so flimsy the one way that I tried taking them out and I thought my window was gunna break... so in some spots there is bondo filling in the dents on the door (these are about the size of a quarter and go in a about half an inch) So I am hoping it will last... I mean I even cut out the part of one of my fenders that was so screwed I would have never fixed it unless I used a ton of bondo...
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Old 12-03-2002, 07:28 AM
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If Bondo is done right it will last a very long time,... I repaired a 32 ford in 1975, and it is still looking good, i chopped the top on a 49 mercury in 1990, and repaired several panels and it is still looking good, what gives bondo a bad name is the way it is put on by someone who does not do the metal preparation first,...good luck, do it right and it will last,.......streetrod936
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Old 12-08-2002, 07:26 AM
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I have a 68 Impala I replace the quarters on and so far its been 8 years and no cracks yet.... knock on wood
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Old 12-10-2002, 09:15 AM
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If it's done right and you use a good product, you have no need to worry about cracking because the repair will outlast the car. Or probably you for that matter,
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Old 12-10-2002, 02:15 PM
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lots of good advice out there, i found years ago that the main cause for bondo-mud to crack other than poor workmanship was,the left over tack coat in the low spots was not removed before the next coat was put on. not a big problem today,that sticky tacky stuff dries hard especially with the better bondo's usg, evercoat, ect.
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Old 07-12-2003, 12:00 PM
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ive been in the body trade over 10 years...no cracking probs unless you do something really stupid...dont worry
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Old 07-12-2003, 02:41 PM
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The only time I have had any cracking issues is when I used fiberglass on a steel car (shaved door handles before I got a mig). I got cracks at the joint.

Where there was body filler on steel, ON THE SAME CAR, no problems. Car was done 10 years ago and have been stored outside ever since.
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Old 07-12-2003, 03:31 PM
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Stoned,
I`
ve never had bondo to crack eather(100rds of gal). Like every one says do it right and it will out live you.

Troy,
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Old 07-12-2003, 03:57 PM
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Is the regular bondo brand bondo good stuff? Or should I buy some other bondo? Yall gettin me a lil worried talking about cracking an everything.
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Old 07-12-2003, 08:02 PM
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The problems I have seen with cracking is usually because of being used at joints that are not tight, therefore flexing. I have also seen it crack when it was just used to fill in a big valley in one step. The stuff usually isn't mixed properly and doesn't harden on the inside for sometime. That causes cracks.

I personally don't use the "Bondo" brand because I like Evercoat.
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