>
> It came up very well. In the long run I'm not a great fan of using
> chemical agents like acid unless there's really no other way to get the
> desired result.
>
> Christopher Ball
> triumph@io.org
I would like to offer a slightly contrary view.
I do have reservations about large scale dipping of parts because of
some of the horror stories I've heard about chemicals being trapped in
interior recess and slowing seeping out over periods of weeks or months,
but I think it's perfectly acceptable on a smaller scale. Most auto
body paint supply stores sell products specifically formulated to
prepare metal surfaces for painting and a good many of them contain
phosphoric acid. They leave a surface coating that not only can be
painted over but increase paint adhesion.
These products include chemicals designed to prepare aluminum for
painting too. For example there is a preparation called Alumaprep (or
something like that) that works like Metalprep. There are also special
test coatings that can be put on aluminum to determine if the surface is
suitable for painting. When the surface turns red (I think that's the
color) then the it's ready for paint.
I'm also of the opinion that the only way to completely remove all
traces of rust from steel is by chemical means. I would even treat a
sandblasted surface with Metalprep before painting it. The only
exception would be where hydrogen embrittlement might result.
Roland
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