Body Filler basics

Bash, if anyone hijacked it it was me not you. I did apologize to Frank back a few posts as that wasn't my intent, if anything you have been trying to help figure this out which is why I posted here as K13 and the rest of the group have much experience and are willing to share.
 
ssmustang said:
OK Neil, will try to fill in more of the story. The 'bubbles' started quite small and kept increasing in size around 2 to 4 months after bringing the car here. They grew until the paint layer cracked open (like the last photo of the 'new' bubble). The 'goo' (it was much thicker than straight oil, more like resin and smelt like an open can of white lightning) was between the new paint and the bodywork layer below. Once it cracked the paint layer the spots never increased in size beyond what they were but the 'bubble' didn't decrease in size either, the paint was intact (hard just separated) when we opened things up to investigate. The bondo whether it was old or new seemed 'soft' to me when we initially dug into it for the repairs. Another thing I remember was as we were stripping the damage here the bondo seemed to harden up again after it was opened up to the air. It was never mush, just softer than I remembered bondo to be when we initially dug into it. The PPG rep here cut out and took chunks for analysis but I never was told what was found. As soon as they found a non PPG primer that was used under the base/clear they exited. The son who was running the S'toon shop was on holidays on Oahu and came over to look and also took samples, again heard nothing on what was found. The worst area of bubbling was where the repair of old damage had been done by the S'toon shop (below quarter window area behind passenger door) but bubbles came up on other areas that were not part of that repair. The rust proofing was done after all the paint was done just before I brought it over here. Thanks for all your help, hope this added info helps, just would be nice to know.
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Funny you mention this as I just removed more than 1/4 inch of bondo around the wheel wells on this early Datsun roadster. Its a 66, I think, fairly rare, and yes, the sheet metal is just barely 20 gauge, but we replaced all the pieces with 18 gauge. What I want to say, is when I ground off the old bondo, it seemed just like you said, not gummy or anything, but it just seemed softer in places, and smelled almost like a fresh can of bondo. It was soft enough that even I noticed it, and I'm far from being a body and paint guy. That bondo was put on in a previous lifetime, as this car has been sitting for a couple decades. It was also bubbled slightly on the surface so you knew there was something bad under it.
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You have made my day JVO!! I was hoping I wasn't the only guy in the world that this happened to. Any other information on what was done, products used so we may find some common factors? I am not a body paint guy either so I know how complicated these things can get especially when trying to remember facts from 20 years ago. Thanks for sharing.
 
OH, I have to say, I will have to re read this thread multiple times in the next few months. If my life goes as planned, I will be doing body and prep work on my Ranchero if the planets all align correctly in the next couple months. After that, I am probably going to adopt some of you as my next best friends, as I decide on what products to use, and how to use them properly.
When I did my model A in a previous lifetime, (the only vehicle I have ever painted myself), I read for months and I was quite confused after reading it all. Just about everything I read was about 50/50 on whether to put bondo on bare metal, or prime it first. What to do, what to do properly??

I am NOT proficient at paint and body work. I only do metal repair, and I aspire to zero bondo, or very very little, but I know I'll still need it. I will probably be asking for help on my Ranchero thread when the time comes. I'm gonna need help, even though it will be just a quickie spray job, cause I can't afford to pay someone to do it.

And no, I don't have any info as to what was done originally to this car. I didn't take any pics before starting, only during construction. The owner came to help me on this, as I'm not into grinding rust and dirty crap. HE did all the dirty work, I made all the patches and welded them in. There was a lot of work that was substandard by today's standards, a little brass here and there, a lot of bondo, and some grey primer sprayed on to cover it all. Looked like it was all done a long time ago.
 
Interesting JVO. I have to say I have never run into that. I have (when stripping an old car) run into cheaper fillers of the day that seem softer (usually Pinkish) but they were softer in the day as well. Mind you almost anything was softer than white lightening.

I will also mention here the reason I am an epoxy guy. You can judge for yourself whether you want to use the epoxy method on yours or not. I like to do all my metal work and rough out work then sand the metal all down with 80grt and shoot a couple coats of epoxy on it. One reason is once it is in epoxy I can come back to it at any time and not have to deal with flash rusting. Reason two is you can do your filler work over top, just scuff it down with 120grt and away you go. This way once again the metal is protected. Lets say you get a scratch or a stone chip in the paint down to the primer or even filler. Now you have a breach in the waterproof coating (paint) and the moisture will be absorbed into the primer/filler (sponges) which will be on top of bare metal, without the barrier of the epoxy primer. So I just think it is cheap insurance for your paint job to last longer. Etch primers are fine as well however you cannot do filler work over the etch so you still have the filler next to bare metal. As I mentioned before the new primers (most of them anyway, some claim direct to metal) do not contain chromates any longer so that means that it will need either etch or epoxy on the bare metal before appling.
 
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