Bondo warp

[bigjus 10+ year member]

I searached around and couldn't find what I was looking for so question: how can I keep bondo from warping my projects? I laid bondo over a FG amp wall I have been working on to mold it into my car's wall, however when it dried the it had warped the glass and caused gaps of about 1" all around. Looks like I'll have to cut this crap off and re-glass/bondo, what can I do to prevent this in the future? Thx.

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[Black_Jesus 10+ year member]

glass it to the wall... lol

 

[xchaosx 10+ year member]

are you just adding bondo over glass fiber? or do you have a glass resin base and how many layers do you have for the base

 

[xchaosx 10+ year member]

since i need more info i'm not sure but it seems as your trying to make it strong with bondo. the bondo is just for smoothing out.... fiber glass and resin are for strength.... too much bondo isn't a good thing and it sounds like your putting too much hardener in it also for it too warp....

 

[bonesninja 5,000+ posts]

most likely he's putting it on too thick as well. when it hardens it shrinks thus causing the warpage. as mentioned above-bondo should never be used for strength or for filling gaps, only for filling in small irregularities in the surface of the item you want smooth. I know everyone saw them filling in holes with bondo on pimp my ride but a real body shop wouldn't ever do that.

 

[req 5,000+ posts]

try using fiberglass reinforced bodyfiller. way stronger than regular bodyfiller. maybe get some higher quality (stuff made by evercoat is supposed to have almost NO warpage\shrinkage)

also - make sure both your resin and filler are based of eaither epoxy or polyeurathane (sp?)

if they are different, they may not stick to each other as well.

and the biggest tip - APPLY IN THIN COATS!!! 1\4" MAX per coat!!!

 

[bigjus 10+ year member]

was being added over a glass/resin base. the glassing wasn't too thick as it wasn't a structural part of the wall, was just to make the top look molded to the car (dammit for not taking pictures...). bondo was used mainly to fill in planned gaps and smooth out other parts that i (wrongly) assumed i could fill in w/ bondo. i wasn't using layers thicker than 1/4", in fact i don't think the 3 coats i added were that thick total. probably wasn't sticking together, they stuck together fine, the dried bondo just shrank waaaay more than expected causing the warpage.