Any tips or tricks to getting body puddly or paint to stick to a braised joint on a body or am I doomed to remove all the br*** and start over? Thanks Gary
A friend of mine went through this. He tinned most or all of the brazing with Lead, and I think the body-paint guy ended up removing most of it and replacing with mig'd metal, but he needs to stand behind his work. I recently purchased a deuce firewall that had probably a 20 year old paint, primer and epoxy primer on it and looked pretty nice. I was surprised when I stripped it that many of patched holes were brazed. It was holding up well, but i drilled them all out and gas welded patches back in. You could be taking a risk, but if you are doing the final paint and body prep, and can rework it if it comes through (may take a long time) it might be minimal. If someone else is doing the final work they may want it removed.
What primer did you apply? I've used DP-40LF (a catalyzed epoxy primer) on brazed seams with no problem. Just made sure it was textured from sanding and cleaned with laquer thinner before shooting. Posted using the Full Custom H.A.M.B. App!
Have not tried any thing on it yet, but have heard lots of horror stories on nothing sticking but do not know what prep work went on before it was coated. Thanks Gary
The only problem that I had was when I didn't get all the flux killed. It cause a little bubble after a couple of hot months. I pierced the bubble with a needle, push it down on a warm day, and forgot about it. I was using all lacquer back then.
I think these joints could be sand blasted and roughed up and cleaned with whatever is best, what do you think. Thanks Gary
Remove all the residual flux and prepare metal as per normal, filler etc before painting. If done correctly it will last a long time. Last thing you want is it bubbling up later under the finished top coat. Years ago when repairing and replacing panels was the norm I used brazing, eg, 1/4 panels and door skin corners after edges were hammered down once door fitted opening. Never had any rework when done correctly.
The flux seems to be what causes problems.....sand blasting the welds then using a good epoxy primer might be your best bet.
When I was doing body work on my Chevy II I found several places where they were brazed from the factory, mostly at corners where two panels meet. They didn't seem to cause much of a problem when the cars were new. But they probably prepared the surface properly, getting rid of all the flux, sanding as needed, etc. If you post some pictures of what you're dealing with, we might be able to advise you better if you'll be able to make it work
This is an old myth. There is no problem with bondo sticking to brazed joints, or lead either for that matter. What they won't stick to is FLUX. You have to get every bit of flux out of the joint or it's no good. Also, the tiniest pin hole will let moisture in from behind and lift the bondo or paint. I have brazed plenty of body repairs. I keep a bucket of water and a rag handy and the second I finish brazing, rub the seam with a wet rag. This minimizes warpage and the flux just pops off. Next, grind the bead down. Just enough to take off the high spots. Then go over it with a wire brush in a drill. Now get a drop light and inspect the seam UP CLOSE. Pick out any embedded flux with an awl or ice pick. I use an old screwdriver ground to a point. If you find any holes braze them up. Sandblasting is great if you have a sandblaster but even if you sandblast the seam you still have to inspect for pin holes. Using this method, I have NEVER had a problem with bondo or paint even after 10 years.
Easy just sandblast the area and put your primer or bondo on before it starts to oxidise. Do it right away actually and squeeze it on to make sure any pin holes are filled.
Was watching one of those TV shows last night that have on car factories and they were at the BENTLEY factory and guess what they still braze several of their panel seams to this day. Nothing special was done to the brazed substrate other the grind, file, and sand smooth. No special primer used they sprayed it at the same time they were doing the whole body. If it works for Bentley you should have no problems. We did the same thing in the dealership I used to work at when replacing quarter panels and never had a come back.
This ^^^^ is the true story. Learn it, love it, live it. This was common practice in all quality body shops back when I was learning the trade. Getting every trace of flux out of the brazed seam was time-consuming and tedious, but did the trick. If even a tiny speck was missed it will come back to haunt you no matter what you put over it. No reputable body shop wanted repair work to come back for re-do so apprentices like me were taught to do it right. Our jobs - and the body shop reputation - depended on it.
#0 some odd years ago I removed all the trim from my 65 Ford truck and filled with br***,,the truck looked good for a long time but eventually the bondo started lifting and today it looks pretty bad sitting in the barn,in the future I will rectify that problem. HRP
I shouldn't tell this but if it was a quicky job or I was in a hurry I would fill holes with a dab of seam sealer or even braze a joint in long tacks and use seam sealer in between, after grinding and cleaning the joint of course. Then cover with bondo. Never had a problem.
I will second all the other replies that are telling you it must be clean. We did rust repairs with br*** for many years with no problems, and Mazda was still using it on quarter panel joints into the eighties.
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