Thanks for the tip on finding this stuff in bulk.
I have a question about using phosphoric acid as a metal prep which is the
active component in the metal prep products sold at auto paint shops.
I am stripping all the paint from my MG Midget in preparation for fixing
some dents, rust out, and removing a PO's bondo artistry (like changing
body contours for some bizarre reason). After I get the paint and bondo
off, I was told to wash the panels with a metal prep solution (I dilute a
phosphoric acid metal prep product 4-1 with water), then wipe it dry. No
rinsing. I have tried this in places and find that the metal does not
re-rust. The only thing I am concerned about is whether the residue (which
shows white - zinc phosphate deposit?) is corrosive. The person who told
me to follow this method was adamant about not rinsing though the
instructions say to rinse.
The metal prep products, btw, contain things like alcohol in addition to
water and phosphoric acid.
Has anyone pre-primed (before the sandable primer) body panels with zinc
chromate paint? This was another tip from the phosphoric-acid fan. I have
found the paint (war surplus cans for now) and notice that it is popular in
the aircraft world, but seems designed for painting aluminum, not steel. I
was told that this paint would provide a very good corrosion protection
layer.
Glenn
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