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GTORon 03-15-2013 07:28 PM

acid base primer
I have a 65 GTO. My sail panels seem to be bubbling, like a seem popping. I had it fixed but they came thru again in six months. I am told that there is an acid based primer (yellow in color_) that is causing that. Is there anything I can do to block whatever is coming thru so I can repair the area without doing the whole car. thanks

69 widetrack 03-15-2013 08:04 PM

It is possible to repair it so that you don't have this problem again...first of all exactly where is it blistering? Is it about half way up the sail panel where the roof would be joined by the quarter, and I take it it's happening on both sides...Do you know what products where used the last time you had it repaired? Sometimes if the wrong product is used on a factory joint where they used a led filler, problems like your experiencing can arise...If you had pictures that would help as well. Let me know and I'll try and help with proper products and procedures so that you can put this issue to bed and enjoy the car.


carolinacustoms 03-15-2013 10:12 PM

Just another thought, If it is on the factory seam, it could be rust under the lead causing your problem. If the last time it was "fixed", it was simply sanded smooth and repainted then the lead will continue to bubble until the underlying rust is fixed. Again pictures and products used would greatly help.:thumbup:


MARTINSR 03-15-2013 10:24 PM

Yep, any way you look at it, sand it down to the metal and get rid of all the junk that could be there. When you hit the lead look at the edges where it hits the metal, how does it look? If you apply some epoxy primer over it you will likely solve it but you may need to remove that lead and start from scratch.


69 widetrack 03-15-2013 10:34 PM

Thanks Kelly, that's exactly where I was going...that lead has been in there for over 40 years almost 50 years and it is the first place to look. I agree with you as well Brian, it's got to go down to bare metal and it should be taken down one layer at a time to see exactly where things are going wrong. All it take is a pin hole in the lead filler to cause blistering and unless it's taken out and repaired properly it will come back and get worse every time. It could have happened the first time it was painted, if it's down to bare metal and a little moisture gets in an area where the lead has been disturbed it will stat to rust from underneath.


tech69 03-16-2013 09:25 AM

I've just recently learned that epoxy is the only thing that should be applied to lead. Is it paint that's bubbling or is the lead being pushed out? Figure that out first.

GTORon 03-16-2013 07:14 PM

Thanks for the help! I tried taking pictures of it but it won't show. It is about 2" from the roof line on both sides. It looks like a river on a map. approx 5" long and bubbled up maybe 1/16 of an inch. I don't know what was used to fix it last time but I assume the standard filler and primer.

carolinacustoms 03-16-2013 09:16 PM

Sounds like a problem under the lead, but could be the primer used did not adhere to the lead. Sorry to be the bearer of bad news, but the only way to fix it and solve the problem is to start sanding. But like someone else said, try to go one layer at a time. That way if it is just a primer problem you arent doing a lot of work that does not need to be done. I personally remove all the lead when I restore a car, just because I have seen it bubble too many times and ruin an expensive and otherwise perfect car. As for only using epoxy over lead, I will agree it would be the best option on the market, however the cars came with lead from the factory and an enamel or laquer based primer, so I would not say epoxy is the only thing you can use over it. I do recommend epoxy over any bare metal though. Best of luck to you.:thumbup:


69 widetrack 03-16-2013 11:30 PM

Good call Kelly, chances are that the issue you have related to the lead joint between the roof and the rear quarter...It's best to remove the damaged area 1 layer at a time to see not only how the problem occurred but, to also find a remedy. As you remove the top coats check for discoloration between layers, check for any signs of moisture between layers. If there is moisture between layers that means that the moisture was trapped when painting. It could have happened in the priming process which may indicate that the lead seam is fine, or this could happen if the lead filled seam was disturbed during the initial prep during the first paint job. look to see if there is regular filler over top of the lead and try to remove some of the plastic filler by prying it off. Look at the underside of the filler for again, discoloration. Then as mentioned, if there is discoloration remove the lead, clean the area (use a sandblaster to remove any rust and with a 50 grit disc, grind the area, apply a coat of Epoxy primer, and fill the area with a plastic filler. Block sand to make the C Pillar straight, apply at least 2 more coats of a sandable epoxy primer. Allow the Epoxy primer to cure, final block, for base coat I would recommend 400 grit dry or 600 grit wet (800 grit wet if your using water born base), base the area and clear.

And to add to Kelly's comment about using primers other than epoxy over a lead filled seam, your right Kelly, before plastic fillers, all panels where either replaced, repaired by a pick and file method and lacquer primed, or filled with lead and primed with a lacquer primer. During those times, lacquer primer was brushed on, sanded and then painted with lacquer paint. Materials have evolved over time and Epoxy Primmer is a big step forward in substrates compared to lacquer or even etch primer.

Taking the top coats off one layer at a time will tell you the story of what happened and give you the information you may need to avoid a problem like this in the future.

I hope this helps.


GTORon 03-17-2013 05:38 PM

Great advise from all of you! I really appreciate it. I will let you know when I get into it what happened. Maybe my problem can help someone else out there. Thanks again.

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