Thread: Electrolysis - A Superior Cleaning Process

Originally Posted by gallegos

I did mine like this with a switch, led and binding posts on the front for the different voltages.

How to Convert a Computer ATX Power Supply to a Lab Power Supply

Thanks for that link. One of my stalled project is a Lab Power Supply based on a simple circuit from the back of a Jaycar CatnDog. It did not work and I have not got back to it. The PC PS is a cheap easy method and sometimes it is easier to have the instruction rather than work things out for yourself.

Dean

Ok here are some of my tips on home electrolysis

• Use scrap steel for Sacrificial Anode, they work are cheap and no real toxic risks
• It works on areas closet to the Anodes fastest (Line of Sight)
• Multiple anodes spread out around the item seem to work better and more evenly
• The Anodes should have equivalent surface area to the part being cleaned or it will be slower and the annode will need to be scraped clean regularily
• Bigger the item/bath the more current required.
• It is an inexact science and slight changes in positioning the anode in relation to the part can affect it working.
• Distance between annode and part affect conductivity
• Water is orange with rusty hydrogen on top when working after a while, when turned off the empty bath settles and the water goes green. No idea why and doubt it matters at all. I did find it an unexpected sight though.
• It can take ages and I am unsure what size, current or condition parts said to be done in an hour would be, expect overnight or longer.
• Parts come out dirty and need a wash & a brush, don't expect it to come out clean.
• If parts are not washed and treated promptly they will flash rust
• The Soda Crystal dissolve easily in hot or cold water
• No noticeable change in temperature to the bath from the electrolysis. (Done outside and it is bloody cold in Melb at present)

These are my observations so far, and there is plenty more info available on the net on what to do and not to do, how to set up etc.



Lat night I used a 90L tub about half full with 2 anodes and it was very slow drawing under 2amps, left it for around 6Hrs and it did form an orange froth on top and came out with a scummy layer over the whole part. Put it back in today with 4 anodes and the meter jumped straight to over 8amps and the charger shut off, reduced it to 4 anodes and it is drawing about 6amps, been in so far for around 4Hrs.

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Initial Setup Day 1






Day 2 Before power

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After 4 Hrs, followed by a quick stir with a bit of wood
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Originally Posted by DSEL74

Ok here are some of my tips on home electrolysis

• Use scrap steel for Sacrificial Anode, they work are cheap and no real toxic risks

Steel anodes still have quite a few problems.
They oxidize or rust as soon as the voltage is applied and as you say need to be cleaned every few hours to maintain a reasonable current - this is the reason it seems to take ages.
The rust contaminates the electrolyte and tanks and makes a real mess and is why the parts come out dirty.

BTW the reason the colour changes from orange to green is that some of the iron in the steel that dissolves away from the anode into the solution is initially in the ferrous state (each atom of iron has lost 2 electrons) and ferrous solutions are green in colour. There should also be some black stuff underneath the orange sludge on the anode. The black stuff is the solid ferrous oxide which eventually gets converted to the ferric oxide (each atom of Fe has lost 3 electrons and is orange in colour), by the oxygen produced near the anode and the atmosphere. The Ferric oxide is insoluble but clings to bubbles in the solution making it look orange and masking the green ferrous colour of the solution. When the current is turned off the Ferric oxide being insoluble precipitates out revealing the ferrous solution.

I have started using Carbon anodes and these are much better than steel. There is no need to clean the electrodes and everything operates a lot cleaner.
You also raise the issue of anode distribution. I find an anode every 20 cm or so around the tank is needed to get an even process.
Also all connects should be done using nuts and bolts (ie no alligator clips). If a clip slips off while the voltage is applied there may be a small spark generated and enough hydrogen around to cause an explosion. Also remember to turn off the power before disconnecting anything.
This problem is exacerbated if, a tall narrow tank is used so use a wide flat tank and make sure the electrolyte fills most of the tank, high voltages/currents are used - there should be no need to use more than 12V and about 10 and preferably ~5A.

Explosions are rare but do happen. There was one last year where someone was de-rusting a truck brake drum in a tall narrow tank and he disconnected the anode before turning the power off. The explosion was a small one but it covered the guy in orange muck and he had to change his trousers.

The other thing not mentioned is bathing the parts in a weak acid solution (vinegar) after the process. This neutralises any alkalinity, which will cause havoc to any paint applied to the item.
FWIW my bath has never gone green.
Bob where did you get your carbon rods from? I have looked at jewelry supplies for carbon stiring rods but they are pretty pricey when you consider how many are needed.
I generally use just one sheet of steel and turn the job every now and then. I find the slower you go the more even the coverage.
Cheers,
Ew

Originally Posted by Ueee

The other thing not mentioned is bathing the parts in a weak acid solution (vinegar) after the process. This neutralises any alkalinity, which will cause havoc to any paint applied to the item.

I wouldn't use vinegar unless it was something like pure spirit vinegar as it may contain organics that would also need to be removed, a good spray wash with a hose should get the soda out but for me a bit of soda remaining doesn't matter as I let the treated objects rust till I can clearly see an orange patina (just a couple of hours is often enough) and then I convert that to ferric phosphate using phosphoric acid. I then air dry the objects till most of the moisture has evaporate away and then bake in a hot BBQ oven till it is completely dry. Some folks wash just off any remaining sticky residue with Meths and let it air dry.

FWIW my bath has never gone green.

It depends on the type and concentration of the electrolyte.

Bob where did you get your carbon rods from? I have looked at jewelry supplies for carbon stiring rods but they are pretty pricey when you consider how many are needed.

! got a pack of 13 mm diam rods from a welding shop like these for $10 because some of them were broken.
Southern Cross Industrial Supplies - Product Detail: CARBON RODS 13MM PKT (50)

I just did a search and found these which would probably do the job
A Man's Toyshop
The thinner ones are cheap but beware that they are then more fragile, even the 13 mm ones don't like being dropped.

They have a copper coating which is a PITA to get off - I found sulphuric acid is the best thing to get the copper off with.

I generally use just one sheet of steel and turn the job every now and then. I find the slower you go the more even the coverage.

Yep

Could you not run the process in reverse (power wise) to get the copper off? I.E copper plate a sacrificial piece of metal?

Originally Posted by DSEL74

Could you not run the process in reverse (power wise) to get the copper off? I.E copper plate a sacrificial piece of metal?

I tried that with the soda electrolyte but it was not that effective (sort of patchy and blotchy) and it took a long time. The ideal solution to do the reverse plating in is sulphuric acid but the sulphuric acid alone will dissolve it off anyway.

Originally Posted by BobL

I tried that with the soda electrolyte but it was not that effective (sort of patchy and blotchy) and it took a long time. The ideal solution to do the reverse plating in is sulphuric acid but the sulphuric acid alone will dissolve it off anyway.

I know it is more dangerous to use but would nitric acid work better than sulphuric. I was under the impression that nitric was the only common acid that would work properly with copper. May be wrong. It has been known .

Dean

Originally Posted by Oldneweng

I know it is more dangerous to use but would nitric acid work better than sulphuric. I was under the impression that nitric was the only common acid that would work properly with copper. May be wrong. It has been known .

Dean

I thought so too so I tried it and even with the most concentrated nitric possible it was not that fast. I also tried aquarregia which can dissolve gold and it too was slow. Electrolytic copper is very pure and pure metals behave very strangely and not always according to what the text books say. I have dissolved a lot of different and ornery metals in my time and I have to say I was surprised how tough this was.

Hey folks,

There seem to be some experienced people here, I hope someone can help. I'm in the process of tidying up an old 1930's IXL Leader 6x40 lathe and I've been trying out electrolysis for cleaning with mixed results.

I tried a test piece first, a cast facing plate of unknown origin (not for my lathe) to see how it worked. It was painted one side and orange rusted on the bare metal face. I've been using Baking Soda and a car battery charger that puts out 1A. My anode is a cut open baby powder tin, being a new Dad I have lots of these and no money . On this piece I didn't measure the current over the piece. This cleaning went well but took a very long time. I could see it bubbling and did get the orange froth. After leaving it on over night for most of a week it came out quite clean with very small amounts of black rust remaining. One thing I did notice was a few bubbles that appear to have been in the casting that have opened up as well as a crater in the back of the piece. It was not there before, so I'm a little puzzled by this.

Never one to let something unexplained slow me down I went on to a non essential piece of the lathe. Only left on once over night, current was around .65-.7A. A lot of the paint is still there and I'm getting this cratering again. I decided to actually stop and diagnose this time.

Anyone come across this? I'm thinking it's one of two things:

1. The part had actually rusted there under the paint. This doesn't make sense to me though.
2. The part was cast with these imperfections and "bogged" at the factory and then painted for appearance. The process has removed this.

When I get some time in the shed I'll take a few snaps.

Any help gratefully received. Thanks gents.

Originally Posted by meastie

I tried a test piece first, a cast facing plate of unknown origin (not for my lathe) to see how it worked. It was painted one side and orange rusted on the bare metal face. I've been using Baking Soda and a car battery charger that puts out 1A.

1A is too low and depending on The size of the piece will take a long time. I found 4 to 5A at 12 V seemed to be effective without generating too much gas. The likelihood of explosions increases with greater voltages and currents.

My anode is a cut open baby powder tin, being a new Dad I have lots of these and no money .

This will be too thin and will erode away very quickly

On this piece I didn't measure the current over the piece. This cleaning went well but took a very long time. I could see it bubbling and did get the orange froth. After leaving it on over night for most of a week it came out quite clean with very small amounts of black rust remaining.
.
.
1. The part had actually rusted there under the paint. This doesn't make sense to me though.
2. The part was cast with these imperfections and "bogged" at the factory and then painted for appearance. The process has removed this.

I'd go for 2. but lets see the pics.

Originally Posted by BobL

I thought so too so I tried it and even with the most concentrated nitric possible it was not that fast. I also tried aquarregia which can dissolve gold and it too was slow. Electrolytic copper is very pure and pure metals behave very strangely and not always according to what the text books say. I have dissolved a lot of different and ornery metals in my time and I have to say I was surprised how tough this was.

Thanks Bob. Saves me doing the experimenting .

Dean

Originally Posted by BobL

1A is too low and depending on The size of the piece will take a long time. I found 4 to 5A at 12 V seemed to be effective without generating too much gas. The likelihood of explosions increases with greater voltages and currents.


This will be too thing and will erode away very quickly


I'd go for 2. but lets see the pics.

Thank you for your response!

I went for 1A for a number of reasons. It was there, and I was following the ideas of this guy: ELECTROLYTIC RUST REMOVAL (ELECTROLYSIS) who favours gentle removal with the theory that more of the part is preserved. It sounded good to me, plus I was a little worried about blowing up the shed!

The formula tin was also used because I had it at hand. It also surrounded the part quite nicely. It was disgusting when done, but seemed to still allow the process to work for as long as I wanted it to run.

I should have also added a 3 to the list;

3. Something I haven't even thought of

Onto pictures.

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IMG_5475.JPG

I guess it's best described as pitting. It definitely wasn't there in the finish before I started. All shots are of the same site, just from a different angle.

Thanks again

Mike