Frank and List,
Mike is absolutely correct on this! Phosphoric acid in a dilute form is
the BEST way to desolve rust and leave the good metal intact. (It is
the active ingriedent in Naval Jelly).
I have further information on this if anyone cares to read a fairly
technical paper concerning rust desolvers.
There is a better way if the parts are relatively small, (the dip tank I
set up at your house Frank). I use electrolytic rust removal, and have
three or four tanks running all the time. Anyone interested in a VERY
safe way to remove rust may contact me.
Kevin
Mike Gigante wrote:
>
> Frank,
>
> The acid you *should* use to treat rust is phosphoric acid, not muriatic
> acid. Muriatic acid is Hydrochloric acid.
>
> Muriatic acid dissolves steel and rust at approximately the same rate
> whereas phosphoric acid eats steel at a much slower rate than rust. Hence
> after treating with phosphoric acid you can dissolve the rust without
> affecting
> the metal much at all whereas with muriatic, you might not have much
> bodywork left by the time the rust is gone!
>
> An additional disadvantage of muriatic acid is that it cause hydrogen
> embrittlement making the structure more prone to cracking and failed
> welds. This apparently cannot be reversed.
>
> With phosphoric acid, bare metal will be left with a protective oxide layer
> and will not rust if kept out of the weather for a reasonable time. If you
> use
> mechanical means of rust removal you have to prime *immediately*
>
> Dulux (aka ICI), and Wattyl (two large automotive paint manufacturers
> here in Australia) both have commercial phosphoric acid treatments. I have
> used Wattyl's and was extremely impressed. I used repeated treatments
> and used a wire brush wheel to remove the deposits between each treatment.
> I continued until I no longer got any heavy black deposits. I have not
> had the rust return.
>
> Mike
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