Most likely, the product Metal Ready contains phosphoric acid. This can be
obtained from a variety of sources.
The two most common acids used to etch metal (which is what the Metal Ready
does) are phosphoric acid and hydrochloric acid. There are some others used
(like "Nital" which I don't recall what it is chemically).
Don't use hydrochloric because it will release chlorine gas as it eats away
the rust. Chlorine gas is exceedingly dangerous. Also, the residual chlorine
can create potential problems for future corrosion (anything with
"chlorides" in it eventually leads to steel corrosion).
Phosphoric acid will nicely etch away the rust and will leave a nice
phosphate (nearly inert) coating.
Water will (eventually) neutralize any acid (acids have pH less than 7.0,
bases have pH greater than 7.0, water is generally around 7.0). You may just
have to use large quantities of the water. If you had, or can remember any
of it, high school chemistry, you'll recall this. Usually, though, in
professional chemical stripping, a series of etches (acid solutions) and
washes (with water and other chemical solutions) is used.
Zinc is also highly toxic (especially if inhaled -- which is why all welding
equipment warns about welding on galvanized metal). It is becoming next to
impossible (thanks to the U.S. EPA) to obtain paints or primers containing
zinc chromate or zinc phosphate. Chromium also is bad, bad, bad. Which is
why it is becoming so hard to find anyone who will do chrome plating anymore
(or if they do, why it costs so darn much).
Lastly, there is a process used to minimize the potential for steel
corrosion (mainly used on stainless steels) called "passivation". It is
essentially boiling the steel in water for a little while. This ties up any
loose molecules of iron on the steel surface with oxygen atoms, thus
creating iron oxide ("rust" in common terms). Oxygen and iron want to very
aggressively combine. When steel is "passivated" the free iron molecules get
tied up with any free oxygen and effectively substantially reducing the
potential for future corrosion. (The iron oxide is very tightly adherent to
the steel surface, thus a fairly effective barrier to further corrosion is
created).
Roy
'60 TR3 TS63103LO (in restoration)
techman@metrolink.net
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