Factory Bondo

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Jan Kolm
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Re: Factory Bondo

#61 Post by Jan Kolm »

Ed Pimm wrote: Fri Mar 13, 2020 12:03 am The factory used red nitrocellulose filler or putty to smooth imperfections after the body's were primed and baked. This filler was applied in a thin film and air dried, no 2 part hardener. It was then wet sanded with the primer. Any old time body man would be familiar with this stuff. Check out the Made by Hand video after the body's leave the bake booth, it can be seen on a few of the body's.
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Harlan Halsey
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Re: Factory Bondo

#62 Post by Harlan Halsey »

Adam Wright wrote: Wed May 27, 2015 11:18 am So the next time someone poo-poo's a skim coat of Bondo remind them that the Factory did far worse.
I don't think so. When we stripped my Convertible D to bare metal in 1972 we found a pinkish plastic filler in the cowl/fender area. Lead of course in all the usual areas. But no "skim coat" It was lead/plastic filler, primer, color.
Today the practice seems to be: metal etching primer everywhere, bondo the original lead areas, bondo the remaining rough areas, skim coat the entire car, prime, color. There is no metal visible when the first coat of primer is shot. This practice makes it much less probable that they will go through the primer when sanding the first time which is why they insist on it. If the metal work is not perfect, a skim coat of Bondo is better than several coats of hi-build primer, or the old glaze, because Bondo shrinks back less than primer.
In the past I have replaced the lead with Marine Tex. An Epoxy filler much harder than Bondo-and consequently much harder to shape.

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Bruce Smith
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Re: Factory Bondo

#63 Post by Bruce Smith »

I agree Harlan. I restored my '60 cab a couple of years ago. The two times it was stripped to bare metal (1980s and now) removed most all signs of the original leading. The body was otherwise very good, and minor repairs with a skim coat was mostly all it needed. But replacing the lead originally used to get the gaps just-right is a talent that most body shops don't have, especially at the doors. So my car suffers door gaps larger than factory. I notice it, and so would you. But 99% of folks don't. It took Best of Show at the Wakins Glen Vintage Councours last year with big door gaps, a skim-coat, and all.
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Adam Wright
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Re: Factory Bondo

#64 Post by Adam Wright »

Harlan Halsey wrote: Fri Jan 20, 2023 5:14 am
Adam Wright wrote: Wed May 27, 2015 11:18 am So the next time someone poo-poo's a skim coat of Bondo remind them that the Factory did far worse.
I don't think so. When we stripped my Convertible D to bare metal in 1972 we found a pinkish plastic filler in the cowl/fender area. Lead of course in all the usual areas. But no "skim coat" It was lead/plastic filler, primer, color.
Today the practice seems to be: metal etching primer everywhere, bondo the original lead areas, bondo the remaining rough areas, skim coat the entire car, prime, color. There is no metal visible when the first coat of primer is shot. This practice makes it much less probable that they will go through the primer when sanding the first time which is why they insist on it. If the metal work is not perfect, a skim coat of Bondo is better than several coats of hi-build primer, or the old glaze, because Bondo shrinks back less than primer.
In the past I have replaced the lead with Marine Tex. An Epoxy filler much harder than Bondo-and consequently much harder to shape.
Harlan, I think you're missing my point. People trash bondo and skimming the car to clean up tiny imperfections. It's the modern way to do it. My point was the Factory would use lead in not great ways sometimes, so the "perfection" people are shooting for by replicating the way the Factory did it is a lost cause. Modern methods work pretty good.
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Bob Forman
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Re: Factory Bondo

#65 Post by Bob Forman »

Bruce, Thank you for that explanation. We removed all the lead from my 62 coupe and made the mistake of not reassembling the car when it was bare. Once painted and put back together we noticed an improper gap in the passenger door. All this time I thought we had somehow tweaked the body during the process.
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George Hussey
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Re: Factory Bondo

#66 Post by George Hussey »

Dan Epperly wrote: Wed May 27, 2015 4:55 pm
C J Murray wrote:Lead is more stable. Plastic is always aging. It's always changing. Rust under either means preparation was poor. Neither is meant to be put on thick so either requires complete metal straightening.
Lead also causes crazing in the paint over time. Today's plastic fillers are far superior to lead, and when used right will last longer than the finish. I do agree people should know what they are getting but. I think it also creates a false notion that a lead finished car is superior to a plastic finished car. Since most people don't use lacquer paint anymore the originality argument on bodywork pretty much goes out the window.


agree. Today's plastic fillers are far superior to lead, and when metal is properly straightened a skim coat of plastic filler is perfectly acceptable. I actually think that we restorers in general create straighter panels than the original factory so do not have to slather on thick coats of lead to achieve straightness. Of course no good body man uses plastic filler more than a skim coat
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Martin Benade
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Re: Factory Bondo

#67 Post by Martin Benade »

Part of the mystique of lead is that it takes a lot of skill to apply and not many can do it any more. I’m convinced that properly applied, polyester filler or lead will last 50 years without a problem. My car even has it thick in a couple of spots, and will outlast me.
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Adam Wright
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Re: Factory Bondo

#68 Post by Adam Wright »

Martin Benade wrote: Fri Jan 20, 2023 2:20 pm Part of the mystique of lead is that it takes a lot of skill to apply and not many can do it any more. I’m convinced that properly applied, polyester filler or lead will last 50 years without a problem. My car even has it thick in a couple of spots, and will outlast me.
Ever meet an old lead guy, there aren't many.
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Re: Factory Bondo

#69 Post by Chuck Allard »

Back in the early '70s I worked with lead repairing Telco aerial cables. I went to a local Porsche repair shop and they showed me how to do lead repair on 356s. I did that for a few years until someone showed me bondo. I tried it and never went back to lead due to the time saved. I decided after a few more years that I liked mechanical work much more than body work and paint. The folks that do that are artists and deserve the big bucks.

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Harlan Halsey
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Re: Factory Bondo

#70 Post by Harlan Halsey »

Bruce Smith wrote: Fri Jan 20, 2023 10:26 am ... But replacing the lead originally used to get the gaps just-right is a talent that most body shops don't have, especially at the doors...
Which is why I use Marine Tex. MT is about as hard or easy to shape as lead but much easier to apply-it goes on like Bondo-but easy to add to if you take a little too much off. The result is that you only have the sculpting part to do. This takes more effort than skill. Some restorers just do the whole thing in Bondo. I think Bondo is a little too weak for panel edges.

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Harlan Halsey
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Re: Factory Bondo

#71 Post by Harlan Halsey »

Adam Wright wrote: Wed May 27, 2015 11:18 am Harlan, I think you're missing my point. People trash bondo and skimming the car to clean up tiny imperfections. It's the modern way to do it. My point was the Factory would use lead in not great ways sometimes, so the "perfection" people are shooting for by replicating the way the Factory did it is a lost cause. Modern methods work pretty good.
Adam: Define "skim". The real purpose of a skim coat is so that if a primer sanding goes through it only hits a high spot in the Bondo. You simply reprime. If on the other hand, there were no skim coat, you would have to lower the metal, and probably Bondo the area, before repriming. That's why most shops skim coat and why those which don't skim coat charge so much. However, the thickness of a skim coat varies shop to shop. The thicker the skim coat the less chance you will sand through it and the easier it is to apply. It seems to me that skim coats vary between a little less than an average of 1/8" to more than 1/4". That's material the 356s didn't have from the factory, and which restorations needn't have today if they get their repair panels from Trevor's Hammer Works or equivalent.
I recall a nicely appearing red Speedster a couple of years ago on which it was difficult to put the side spear on the door because the Bondo was so thick.
Modern methods can work very well, and even better than the factory leading, but probably not as well if you skim the entire car with Bondo. However a very acceptable job can be done if the skim coat is thin enough. At least that's my opinion.

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Re: Factory Bondo

#72 Post by Jan Kolm »

Adam Wright wrote: Fri Jan 20, 2023 3:05 pm
Martin Benade wrote: Fri Jan 20, 2023 2:20 pm Part of the mystique of lead is that it takes a lot of skill to apply and not many can do it any more. I’m convinced that properly applied, polyester filler or lead will last 50 years without a problem. My car even has it thick in a couple of spots, and will outlast me.
Ever meet an old lead guy, there aren't many.
Or in any other profession that involved prolonged exposure to lead for that matter (e.g., linotype operators, wire-wrap circuit board assemblers, plumbers, painters, et cetera).
Jan Kolm
356 Registry #1066
1960 1600N Coupe

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