Discussion Forum Archive - July 2002 to December 2002

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Re: re;aluminium corrosion (from last year)

From: Bill Sheehan   Australia        [email protected]
Date: 05 Jan 2003
Time: 08:00:08
Remote Name: 203.29.131.4

Comments

To get back to the original question, as Ian mostly said - cut out and replace the badly-affected areas, clean up the rest properly, use etch primer (you can get it in black now, but whatever the colour, you only mist it on, don't put on thickly as you would top-coats), put on plenty of paint over that. Enough thicknesses of paint will stop electolytic action provided you keep the water out. Remember it won't be subjected to the same neglect in the next 70 years as it has in the past 70. If you oxy-weld the ali, scrub vigourously after with strong detergent and a stainless steel brush, otherwise your problem will be the flux eating it's way up through the paint in a couple of years - whether the surface gets wet or not. (Even though I have a MIG and access to a TIG I usually gas-weld aluminium skins, but that might start another debate!) If you're worried that the heat (whilst welding ali) might affect the steel or whatever behind it, slip a sheet of copper in between - this also stops the weld going too far through that could cause problems with the resultant "lump" between skins. As Ian said, use a plastic rotary or whatever to clean the surface. And NEVER use steel wool on ali, even to clean for welding - use stainless-steel wool and/or brushes. Good luck. Cheers, Bill


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