Electrolysis

One of the things I managed to hold on to when our PCB factory shut down was a 300A 2V DC supply that we made some years ago for them. It is full-wave rectified and smoothed with a big choke and electrolytics, but being a straight DC supply had to have a variac on the input to regulate the output voltage and current.

One of the projects for this winter is a bit of electrolysis, mainly rust removal, on some engine parts. There are a couple of big tanks at the factory but I haven't got room for them so I'll use a standard water tank instead.

I know there has been a lot of discussion over the years about electrolysis, and would appreciate any practical info on the subject.

(I posted this to the stationary engine and model engineering groups but it was not cross-posted to avoid too much repetition of posts)

Peter

-- Peter A Forbes Prepair Ltd, Luton, UK snipped-for-privacy@easynet.co.uk

formatting link

Reply to
Prepair Ltd
Loading thread data ...

Real easy to do. And, you dont need all them volts and amps. A simple car battery charger will work fine.

Fill the tank with water, plus some washing soda. The exact amount is not critical, but if you use too little, it will not work as well. About 1 tablespoonful per gallon seems about right.

Put a stainless steel plate in the tank, and couple it to the positive of the charger. The plate should be as large as convenient, so that it has a reasonable surface area. (I use one 3 ft long, x 4", fixed vertically at one side of the tank.)

Clean off enough of the rust on the item to be treated to enable a decent electrical connection to be made. Attach wire to it, and to the negative on the charger.

Immerse in liquid. Switch on, and there should be a small current flowing (assuming you have a meter on your charger). There should also be fine bubbles on the surface of the rusty item.

Go and do something else while it cooks. It may take anything from a couple of hours, to a couple of days. Works well, and strips paint of too.

formatting link
Model Engineering, Steam Engine, and Railway technical pages.

Reply to
alan

Thanks for that, one of the things mentioned on the USA sites is that Stainless electrodes produce Chromates in the electrolyte which are toxic and in some states cannot be disposed of easily. Any comment on that?

Peter

-- Peter & Rita Forbes Email Address: snipped-for-privacy@easynet.co.uk Web Pages for Engine Preservation:

formatting link

Reply to
Peter A Forbes

Yep. Firstly I am glad I am not in the USA. We have enough rules here, without suffering theirs!

I dont know if it does produce chromates or not, but I would guess that in the quantities that most of us use, the amounts would be minute. I assume that in so doing, it would eat away the stainless plate. (Ok, so this is based upon logic, and not chemistry.) My plate, which is about 36" x 4" x 18 gauge, has lasted some 20 years or so. When I last looked at it, there was no noticeable wear and the plate looked as good as new.

I dont propose to worry about it. Alan

Reply to
alan

a> Yep. Firstly I am glad I am not in the USA. a> We have enough rules here, without suffering theirs!

a> I dont know if it does produce chromates or not, but I would guess that in a> the quantities that most of us use, the amounts would be minute. a> I assume that in so doing, it would eat away the stainless plate. (Ok, so a> this is based upon logic, and not chemistry.) a> My plate, which is about 36" x 4" x 18 gauge, has lasted some 20 years or a> so. a> When I last looked at it, there was no noticeable wear and the plate looked a> as good as new.

a> I dont propose to worry about it. a> Alan

And if you worry, just use a mild steel plate instead. It lasts very long in an alkaline solution.

Reply to
Ole-Hjalmar Kristensen

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.