Re: electrolytic derusting

Mark Dunning wrote:
"Grant Erwin" <grant@xxxxxxxxxxxxxxxxxx> wrote in message news:13an1vmi032h70e@xxxxxxxxxxxxxxxxxxxxx

I'm writing this posting to report on my experiment with using lead ***
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 *** 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 *** 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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Derusting steel or iron can be done usng just old battery acid.
Ive been collecting wrought iron tools for many years
there the ones made before the bessemer steel process was developed in around 1860/70.
I usually heat up the iron or steel in a wood fire to remove the years of dirt, grease and thick rust.
Scrap off the worst and wire brush.
then place in a plastic bucket or plant trough if it say a 3ft long item, cover with old battery acid, thats sulfuric and leave overnight.
Pull out the next day and wash off with soapy water. Wire brush again to remove the black residues, or iron sulphate, and rinse again.
Especially on wrought iron it brings up the grain structure a real treat. On steel it leaves it a matt grey colour.
I usually then neutralise with washing soda, rinse in hot water and wire brush again. When really dry, I usually varnish to prevent further rusting.


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