List,
Years ago I was at a Redi-Strip franchise and watched a car body
going in a tank. When it finally settled in I saw a spark where it made
electrical contact. I asked "What are you doing, plating the rust off?"
The propriator mumbled some gibberish, which told me I was on to
something pretty simple, and I found out later just how simple it was...
I finally got around to making up a de-rusting apparatus. It works
great, and little by little the rusty artifacts around here are turning
into good looking satin grey parts. It's especially rewarding to treat a
hard to sand part like a steel wheel.
Plating shops pickle (HCl) rust off (it's fast). This can introduce
small Hydrogen molecules into the matrix of the steel, which over time
travel and can introduce structural flaws and subsequent failure
(Hydrogen embrittlement). Most, but not all, plating processes can do
the same thing. An electric rust removal technique with subsequent
painting or, say, electroless nickel plating, should not introduce free
Hydrogen nor introduce a hazard in a tempered, stressed steel part.
Also, you may be aware that a plated / got rusty/ got re-plated part
doesn't last long without going rusty again. That's because free Oxygen
gets introduced into the part when the initial rusting takes place, and
that oxygen in the part will eventually react and produce rust again.
This electric de-rusting process supposedly drives off the free oxygen
as well...
I'm also pretty sure the mild alkali solution with rust is good for
making grass green here in acid-rich soil New England; somebody told me
once that the Chem-Lawn guys put iron in their juice as it makes grass
greener.
http://www.metalwebnews.com/howto/rust/rust.html
Remember, if it's hard, it's wrong! Bob Jepson in Boston
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