Bondo that wont completely cure?

[galacticmonkey 5,000+ posts]

I put some bondo on something I glassed about two days ago. It isnt the super cheap Bondo, its the one step up (I forget what it is, but its the green stuff from Walmart). Anyway, Ive used bondo a few times, and have never had any problems. This time, it wont cure completely. I used the same amount of hardener that I have always used (the recommended amount, maybe a little less to have more work time since Im slow), and it just wont completely cure. The outside is mostly cured, but when I hit it with my sander, it takes off the top layer and then layer just underneath is still slightly tacky.

Is there any way to fix this? I read somewhere that the cream hardener is just a cream version of the MEKP that is used to catalyze fiberglass resin, so if thats true, maybe just give it a mist of some MEKP? Or is it not the same sort of chemical? Either way, this *****. Anybody have any ideas on how I could fix or at least salvage the project?

Click to read more...

 

[NutHugger 10+ year member]

take a heatgun to it. 350 degrees about 6-8 inches away for about 20-30 seconds tops.

 

[Renzone3 10+ year member]

Poly-Flex i assume correct?

 

[Renzone3 10+ year member]

I work at a body shop if you didnt add enough hardner it wont do any good putting a heat gun to it..

 

[galacticmonkey 5,000+ posts]

I fail so hard. So it will just never harden? I figured that any amount of hardener will eventually catalyze the reaction and would eventually get hard if mixed well enough. Apparently Im wrong?

 

[kmanian 5,000+ posts]

I work at a body shop if you didnt add enough hardner it wont do any good putting a heat gun to it..

agreed, also if your hardner was bad it will not cure.

Was it mixed 100%?

 

[Renzone3 10+ year member]

Nope.It either wasnt mixed all the way through or you didnt use enough hardner,you could probably grasp the corner and the whole area where you used bondo will come off completely if you pull on it.This happens to me here and there so dont feel too bad,and ive been in collision biz for the last 4 1/2 years.I always peel it off and do it over again even though it ***** to do it all over again.//content.invisioncic.com/y282845/emoticons/eek.gif.771b7a90cf45cabdc554ff1121c21c4a.gif

 

[snoopdan 5,000+ posts]

redux is in order. Should of just used the cheap **** if you're doing door panels.

 

[galacticmonkey 5,000+ posts]

Its just a little fiberglass box for an 8" subwoofer. Im just using it as practice on my fiberglass/bodywork technique so that if I ever attempt anything like a door panel this wont happen.

 

[mlstrass 5,000+ posts]

Sounds like Bondo brand "chop mat" which is fiberglass. As stated peel it off and start over. Maybe get a new tube of hardener or do a small test batch and let it cure on a piece of scrap wood. Should be ready to sand in about 20 minutes...

 

[subzero 5,000+ posts]

Start over... make build log so we can see what your doing wrong.