Re: electrolytic derusting


"Grant Erwin" <grant@xxxxxxxxxxxxxxxxxx> wrote in message
news:13an1vmi032h70e@xxxxxxxxxxxxxxxxxxxxx
I'm writing this posting to report on my experiment with using lead sheet
as the cathode in electrolytic derusting.

Most if not all of the writeups on the Internet suggest just using steel
for the cathode. The cathode is the electrode in the electrolyte solution
which is connected to the positive lead from the battery charger. I have
done quite a bit of EDR using steel as the cathode, and I invariably had a
problem. The problem was that the steel would rust, and once it rusted,
the current through it would drop, so I'd have to keep pulling it out and
scrubbing it off to get it going again.

I don't like the idea of using stainless either, as the chromium is
reported to come out in the solution, making the solution very toxic
indeed.

I know that car batteries use lead for electrodes, so I wanted to try it.
I took a rusty gate hinge and cut off a sheet of lead and set up the
solution yesterday and got it stabilized at about 5 amps current, which
led to a nice foaming action but without the clamps getting too hot.

This morning the current was still 5 amps, meaning the immediate problem
of the cathode's resistance growing is avoided by using lead. The part was
clean.

I didn't use fresh solution, so I can't say if the solution got as nasty
as it does when you use a steel cathode.

My other concern was the cathode eroding, as it does when I used graphite
electrodes. Those wear away over time, and the solution turns black. The
lead did turn a dark brown color but it showed no signs whatever of
wearing away.

My conclusion is that sheet lead makes an excellent cathode for
electrolytic derusting, surpassing steel, stainless steel or graphite.

Grant Erwin
Kirkland, Washington


I've been using rebar in my tank. Works pretty swell......

I grabbed a chunk of stainless steel, but then learned that it creates a
toxic mess in the washing soda solution.

What are the implications of using lead as the positive ..Cathode?
Electrode? vis a vis putting toxic nasties into the solution?

Anyone?

Mark



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