Moisture and bondo? (1 Viewer)

[Igotmearedone]

Hey everyone. I know bondo is generally hated, but there's already lot of "aftermarket" things done with the body on my '74 fj40 already, so I didn't mind using a little bit before priming the quarterpanel. But now I see little wet spots in it and I don't know how the moisture got there. It's always covered and no matter how dry the weather is, it shows. And now there's a crack in a part of it that you can see below. It seems like I should get to the bottom of this before putting the topcoat on to make the bondo last longer, right? I'm looking for a fix that can last me just a few years and get me back on the road ASAP. Is redoing it all the only way? Thanks.

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[DangerNoodle]

Have you tried wiping those spots away with a degreaser? It may be an oil soaking through. The crack is a much bigger problem. I would suspect that the base metal was not prepped well enough for it to stick or there was a soft spot from lack of mixing. Personally, I would completely redo it, but that it up to you. Normally, I would recomend a thick layer of good expoy primer on bare metal prepped well with 80 grit, and then bondo over that. If you don't burn through the epoxy in prep, you have a much better seal against moisture than direct bondo on metal, as the bondo will absorb and hold moisture from the air. Moisture against bare metal is never good. There are plenty of conflicting opinions on this, but all the really good body guys that I have learned from recomend a sealer before bondo.

 

[Skreddy]

I agree. I like epoxy primer on bare metal as well, then filler, then I reduce the epoxy to use as a sealer. I would bet the spots and crack are in the prep or the product. Did you use actual Bondo brand? Once you try a good filler like an evercoat product, you’ll never use Bondo brand again. But filler in general does like to soak moisture I hear.

 

[Igotmearedone]

Ok, I'll try 1 round of degreaser, but y'all are probably right. It was my first time using/mixing Bondo (and i used that brand, not evercoat) and I did it on bare metal. I'll redo these areas and try epoxy primer first. Either of you think self-etching primer could do the trick instead of epoxy primer? I only ask because I have some and wouldn't have to go buy the epoxy.

 

[Skreddy]

All depends on the data sheets of everything you’re using. My topcoat paint said no self etching.

 

[DangerNoodle]

Ok, I'll try 1 round of degreaser, but y'all are probably right. It was my first time using/mixing Bondo (and i used that brand, not evercoat) and I did it on bare metal. I'll redo these areas and try epoxy primer first. Either of you think self-etching primer could do the trick instead of epoxy primer? I only ask because I have some and wouldn't have to go buy the epoxy.

Self etching won't seal quite like an epoxy. I would recomend a good epoxy. Don't cheap out on primer. Same goes with filler. I like the 3M Platinum Plus filler. It is expensive, but it works very well.