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Registered
Join Date: Sep 2002
Location: Stellenbosch, South Africa
Posts: 888
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Galvanising and re-painting question
After reading a couple of threads on re-paintings and rust issues on bare metal finishes, I have a question for the gurus out there:
If a car is stripped from old paint and sanded down, how much of the original galvanising is left (on post-77 cars, of course) on the outside to offer good long-term corrosion protection? Galvanising offers cathodic corrosion protection, and so it is effective even if small areas are exposed to the underlying bare steel surface (like a bad rock chip), but after a full strip and sanding, who knows? Of course, in those days the body shells were hot-dipped on both sides, so you would still have the cathodic protection on the inside, where you probably need it most. I work for a steel company supplying the automotive industry amongst others, so I know exactly how thin the galvanising layer is we apply. It varies per customer specification, but can be as thin as 45g/sq m. Nowadays, it is mostly applied electrolytically, although hot-dipped sheet is coming back as quality improves and costs come down. It would be nice if anyone can offer direct experience or knowledge to satisfy my curiosity. Can you tell my car was re-painted by the PO some time ago?? LeRoux
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'90 964 C2 coupe (sold  )There are no old Porsches, only new owners. |
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06-03-2003, 06:26 AM
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Heck, I’m only 5 not 71!
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In my own case I have prevented damage to most of the galvanizing on my car by using a quality paint stripper with a plastic scraper. No sanding would be required since the stripper has no effect on the galvanizing. Using a air-die grinder with wire wheel to remove undercoating works well with a little care the galvanizing can be saved also. Where the factory did welding there was no galvanizing left due to grinding and sanding. If I knew of a way to safely regalvanize the body as a DIYer in my garage I would do it as long as the cost wasn't prohibitive. Unfortunately I have no info on how that could be accomplished.
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Pat Henry Targa80 1980SC Targa (Mocha Brown) |
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06-03-2003, 07:04 AM
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A pretty close alternate to galvanizing is to use a zinc primer in lieu of regular primer. Do a internet search on zinc primer and zinc rich primer for additional info.
You will have to get everything off the metal in order to reap the benefits of zinc primer. Website with info on galvanizing http://www.bins-n-benches.freeserve.co.uk/introduction%20to%20hot%20dipped%20galvanising%20f rom%20bins-n-benches.htm Last edited by ruf-porsche; 06-03-2003 at 07:50 AM.. |
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06-03-2003, 07:33 AM
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