Thanks for the feedback. That DEFINITELY merits some further study. After all, one doesn't
want birds to determine the placement of "markings" on one's MV!
However, what I had in mind when I mentioned water-based paints was the latest generation
of waterborne aromatic urethane or polyamide epoxy priming systems, rather than final
coats (although I've heard some success stories about water-based final paint systems
too).
Do you happen to know what brands of paint were involved with this problem? I'd be
interested to know.
Waterborne primers (as well as two-part self-etching primers that incorporate alcohol in
their mix) should work nicely for dip-cleaned metal assemblies. Typically, when you
dip-clean a frame, body, or other complex component, the chemical brew usually manages to
penetrate into every nook and cranny of the assembly. Even after several days of drying
out in a warm, low-humidity environment, there can still be pockets of moisture in the
deepest recesses. This is one reason why I like this type of primer. With a waterborne
primer, or by adding alcohol, not only can an etchant, such as phosphoric acid, be added
to the paint, but the paint is also not easily repelled by these pockets of moisture. On
the contrary, it might even be drawn into these spots to some degree. A thin,
self-etching, zinc primer can penetrate into these crevices and deposit the zinc
phosphate, etc. in areas that might otherwise reject the entrance and adherance of most
other paint systems. Also, the self-etching primers have superb adhesion to bare metal,
and I would suspect that they might enhance the contact with the zinc somehow to improve
its performance as a sacrificial anode, although that's just a gut feeling, since I'm not
a trained chemist. They work great on aluminum, too.
Alan
R. Notton wrote:
> Message text written by Alan Bowes
> >You might also want to look at some of the new water-based systems.<
>
> Hi,
> You might want to be a bit careful too after putting in a lot of hard work.
> Both GM (Vauxhall-UK, Opel-Europe) and BMW (!) are in trouble with water
> based paint on current manufacture. Apparently these paints are being
> seriously affected by some types of tree sap and bird droppings which are
> acidic.
> The topic has made national TV here on various consumer programmes.
> Richard
> (Southampton UK)
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