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Re: [T3] Rust


> Any suggestions on how to best battle rust that has already started
> bubbling-up under the paint.
>

How big an area is affected, and where is it?
Rust can come through from the back of a panel, or from damaged paint on the
front which has rusted and been painted over.

When repairing rusty metal you need to remove all the rust - either by cutting
out or by grit blasting or sanding it off - to about 1/2" further out than the
visible rust goes.  Since it quickly produces microscopic paths of corrosion
into the steel it's not always easy to know if you've removed it all.  A
phosphating layer will give you a second line of defence (rust treatment) but
they are not generally as effective as the manufacturers would have you believe.

VW uses rust-free metal and phosphate coating, primer and topcoat and even that
fails eventually!

For small spots, a spot blaster is very useful - it collects the grit for
re-use, and has various rubber masks so you don't hit too much else, but you
need a compressor.

If it's a bigger area, you just do more of the same, but may also need to
reinforce the area if a lot of it is thin.  Don't write off glass-fibre repairs
as temporary; some of the fine cloth will conform to any curve and lasts well if
put on clean metal - it's a good method for doing the bottom of the rear
fenders, but you need some access to the rear of the panel to make a decent job.
Avoid using it on structurally important parts.

A zinc-rich primer also helps, but make sure it is compatible with the other
paint coats you plan to put on.

Dave.
UK VW Type 3 & 4 Club
http://www.hallvw.clara.co.uk/
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