greenman62@hotmail.com wrote:
>
> >and it left quite a nasty "scar". Rust-Mort is a high percentage of
> >phosphoric acid, which is probably similar to what's used in a dip tank.
>
> I think most strippers use an alkaly-type of stripping agent and
> yes, it generally is not good for non-ferrous materials including
> aluminum. I'm not sure but I think the stripper is similar to the
> stuff machine shops use in a hot tank. This will also include the
> body caulk or whatever they call that seam sealing material.
>
> Phosphoric acid is also used but not as the primary stripping
> agent. It is used to kill the alkaly stripper and to etch the
> steel for painting...
Hot tanking uses caustic materials (lye-based, therefore alkaline) and
will eat aluminum. Phosphoric acid is, as suggested, an acid, but is
used because phosphoric acid converts rust to an iron phosphate, making
it inert. Nevertheless, it is probably not good for aluminum, either--it
probably won't eat it away, as would hot-tanking, but would probably
etch the surface.
As for plastic-media blasting, I have had this done on commercial jobs,
and it will not strip all rust from steel. It does not have the digging
power to get rust out of pits, or to completely remove deep surface
rust. Light surface rust, yes. It is very gentle on surfaces, but that
is its downside--it does not have any significant cutting power. If the
part to be stripped has considerable rust, and embedded rust, don't
bother. Light sandblast or dip.
Cheers.
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