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rcx822
Joined: 31 Dec 2010 Posts: 112
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Posted: Sun Jan 02, 2011 8:33 am Post subject: Rust proofing newly welded closed sections |
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I am looking at welding up some sections which will then be inaccessible inside in order to paint and rust proof them from the inside. I've done some Googling, and found tutorials that recommend painting the parts with weld-through primer and then welding. But doesn't that leave the weld exposed to rust?
I am thinking of drilling some access holes and then finding some nozzle that can fit in an paint the inside.
Any advice on the subject appreciated. |
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buzzy bee
Joined: 23 Nov 2007 Posts: 3382 Location: South Cheshire
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Posted: Sun Jan 02, 2011 11:53 am Post subject: |
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Hi
Galvanise it, or dip it, or electrostatically paint it, or drill holes and wax it.
Cheers
Dave |
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Bellisin
Joined: 19 Dec 2010 Posts: 16
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Posted: Wed Jan 05, 2011 7:27 pm Post subject: |
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The weld through primer is good in that it will give protection without interferring with your weld. It can also help the welding a little too. Nevertheless it will burn away around the weld and of course the weld material itself will not be protected.
I would use the weld through primer but then waxoil the cavity afterwards. The weldthrough will protect any gaps in the waxiol protection whilst hopefully the waxoil will cover the newly welded metal.
I hope this answers your question.
Stuart |
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baconsdozen
Joined: 03 Dec 2007 Posts: 1119 Location: Under the car.
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Posted: Thu Jan 06, 2011 1:09 pm Post subject: |
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If spraying waxoyl or whatever inside a box section make sure you get plenty of it in there.Any area thats not covered will rust far quicker thand if the whole lot had been left untreated.
Some while back I spent some time testing various anti rust paints etc (coming to the conclusion that one very well known paint is worse than useless) and asked some of the off shore companies what they used. A large flat steel sheet does suprising well if untreated but any paint,grease or oil (other than a sacrificial system) that leaves areas bare simply makes things worse. _________________ Thirty years selling imperial hand tools for old machinery(Now happily retired). |
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ukdave2002
Joined: 23 Nov 2007 Posts: 4100 Location: South Cheshire
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Posted: Sat Jan 08, 2011 8:51 am Post subject: |
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The original Mini's had the inner and outer sill void filled with expanding foam, reputably the sills on these cars on these cars outlasted the later non filled by a considerable factor. I have no idea why BMC stopped doing it, neither am I aware of any other vehicle manufacturer using this process?
I kinda get the logic; in a box section condensation will always form from the air and its this that causes the corrosion rather than water seeping in. By filling with foam the air is mainly removed so condensation is almost completely eliminated. The type of foam used wont absorb water either.
I suspect there is a good reason why its not a more commonly used process, anyone know why?
Dave |
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Kelsham
Joined: 18 Jan 2009 Posts: 349 Location: Llandrindod Wells Powys
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Posted: Sat Jan 08, 2011 3:59 pm Post subject: rustproofing |
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Back in the late 1960s I fancied myself as a car dealer and began to specialise in buying selling and repairing Mini's.
One Mini I bought had rusty sills, I tackled the repair with some sills I had made up locally.
I was surprised to find the foam filling. It obviously had failed on this car.
BMC soon stopped injecting it. I would assume that as the car I was welding was only about 8 years old ,that the experiment with foam was a failure.
It was dificult to remove to carry out the repair. Lots of fumes.
Regards Kels. |
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baconsdozen
Joined: 03 Dec 2007 Posts: 1119 Location: Under the car.
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