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Steamwhisperer
17th Jul 2018, 10:28 AM
Hi all
A few of my tools got wet and about 5 years later I noticed it. :(( Being a bit lazy now, I decided to set up an electrolysis bath.
I have most of the pics but the impressive ones of the files (before and afters) disappeared somewhere in the very cheap USB stick (that I will never buy again) while transferring them from my phone. :((:((
The files were throw-aways and ended up very very useable.
Hopefully you guys will read this and let me know if I've gone about it the wrong way. :2tsup:
It worked but I still don't know...

Phil

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BobL
17th Jul 2018, 11:12 AM
There's nothing wrong with what you did, especially the setup, my comments are just suggested improvements.

Anode material.
Ferrous (except something like stainless) anodes will corrode forming a sludgy insulating layer over the anode which reduces the current and slows down the electrolysis. For large items the anode needs to be regularly cleaned which is messy. You wont pick up the insulating factor unless an ammeter is used in the circuit. Ferrous anodes also turns the electrolyte a messy orange brown which makes it less likely you will reuse the electrolyte. A better anode material is carbon arc rod. The Carbon corrodes much slower than anything ferrous and turns the electrolyte light grey but it can be reused over and over again, some of my solutions have been used more than a dozen times. Stainless also does not corrode very quickly but contains Co so there is some concern about using this.

Electrolyte.
Washing soda sometimes contains Sodium Phosphate but I note yours says "Does not contain Phosphates" which is good as we already dump too much phosphate into our waste water. A "soda" which you can be confident has no phosphate in it is "Foot bath salts" (also available at supermarket) which uses Sodium Carbonate.

Power supply.
A battery charger typically outputs 14V which is way more volts than is needed. As little as 3V is all that is required. The effect of using higher voltages is that excess hydrogen and oxygen are produced which can be dangerous if the electrolysis is performed in tall narrow containers or inside a small room. They are not easy to find but something like a 6V Power supply with variable current output is ideal for this sort of thing. Being able to adjust the current can speed things up - this can be done to some extent via the power supply and adjusting the concentration of the electrolyte. Typically I make dilute and concentrated solutions of electrolyte - 2/3 fill the bath with the dilute solution and then watching the ammeter slowly add concentrated solution until it gets to ~5A.

Wimmera Jack
17th Jul 2018, 11:12 AM
Phil, you are a perfectionist. Bob has added some good advice.

John

Steamwhisperer
17th Jul 2018, 02:16 PM
Thanks John
very kind words, really pleased with how the bits turned out. I did some pin punches and a chisel as well (pics coming). Pity about the pics of the files though.

I was hoping you would respond BobL, fantastic information as usual and definitely going to source some carbon rods. Many many thanks for your input. Love it.

Phil

Steamwhisperer
17th Jul 2018, 05:02 PM
Some more pics. as I say it is annoying losing the before pics of the files as they had barnacles on them.

Phil
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simonl
17th Jul 2018, 05:53 PM
Thats nice work Phil. Ive had a play with this but my setup was not as elaborate as yours!

Thanks for posting!

Simon

Sent from my SM-G900I using Tapatalk

waxen
17th Jul 2018, 10:54 PM
Just be aware of
hydrogen embrittlement, baking in an oven will fix that

BobL
18th Jul 2018, 12:37 AM
Just be aware of
hydrogen embrittlement, baking in an oven will fix that

MUCH less of a problem if lower voltages are used.

DSEL74
18th Jul 2018, 11:58 AM
Watch out for springs they tend to break after electrolysis and make sure there isn’t any brass bushes etc as they dissolve.

Karl Robbers
19th Aug 2018, 06:27 PM
I'm planning on doing something similar and was wondering what quantities of soda should be used used per liter of water? For power source, I will be using an old Arlec 6/12/24V battery charger, naturally on the 6V setting. Stainless steel was probably going to be my anode choice, but I'm having second thoughts since BobL's comments regarding Cobalt. Is the concern due to the Cobalt leaching from the stainless and thus becoming a heavy metal poisoning concern? I have some 6.3mm Copper coated carbon arc rods, would these be okay?

BobL
19th Aug 2018, 08:18 PM
I'm planning on doing something similar and was wondering what quantities of soda should be used used per liter of water?

The way I do its to make up a concentrated stock solution of 200g/L and then dilute some of this to about 5:1 as a working solution. I have a 6V adjustable current power supply and set the current between 3 and 5A. Making a concentrated solution saves space and allows you to adjust things on the fly.

If you only have a fixed V power supply and an ammeter you can adjust the concentration (up with more concentrated, and down with water) until the current reaches about 3 - 5A.

If you don't have an ammeter try 40g/L and if there's not enough bubbles after a minute or so chuck in some more soda or if its bubbling like mad pour in some water.


For power source, I will be using an old Arlec 6/12/24V battery charger, naturally on the 6V setting. Stainless steel was probably going to be my anode choice, but I'm having second thoughts since BobL's comments regarding Cobalt. Is the concern due to the Cobalt leaching from the stainless and thus becoming a heavy metal poisoning concern? I have some 6.3mm Copper coated carbon arc rods, would these be okay?

I can't for the life of me remember why but I found iy worked better if the copper was removed. It can be dissolved off with some battery acid.

waxen
19th Aug 2018, 09:14 PM
My method is a little cruder, I use half a packet of bath salts to a bucket of water. I use a combination of a reo mesh mat and carbon rods.

BobL
19th Aug 2018, 09:35 PM
My method is a little cruder, I use half a packet of bath salts to a bucket of water. I use a combination of a reo mesh mat and carbon rods.

From memory the bath salts packets are 500g , and buckets are ~7-10L so thats between ~50 and 70g/L

BaronJ
19th Aug 2018, 10:18 PM
I'm planning on doing something similar and was wondering what quantities of soda should be used used per liter of water? For power source, I will be using an old Arlec 6/12/24V battery charger, naturally on the 6V setting. Stainless steel was probably going to be my anode choice, but I'm having second thoughts since BobL's comments regarding Cobalt. Is the concern due to the Cobalt leaching from the stainless and thus becoming a heavy metal poisoning concern? I have some 6.3mm Copper coated carbon arc rods, would these be okay?


Hi Karl,
I think the issue is Chromium rather than Cobalt.

Karl Robbers
27th Sep 2018, 03:52 PM
Well, it's taken me a month or so, but I have finally had a crack at electrolytic rust removal and I absolutely love it!
My set up was as follows. One 20L plastic bucket from Bunnings, 4 pieces of stainless steel 50 wide, 400 long and 1.6mm thick (yes I know I had grand plans for using carbon electrodes, but I didn't have any acid to dissolve the copper off and I did have stainless steel sheet), one Arlec 6-12-24V battery charger and a packet of washing soda. I used a solution of 600G washing soda to 15L of water, plus I made up the remaining 400G with 4L of water so I could adjust things as per BobL's suggestion. Having hung the P&N tap handle off a piece of wood using .9mm steel mig wire I turned the charger on and observed a Current of 1.9A @ 6V using a clamp meter. I then added the more concentrated solution until I got a reading of 3.2A. The final solution ended up at 18L water and 900G washing soda, so 50G/L. I noted that after a while the current actually increased to 5A on the negative side, while the positive side showed 3.5A which I found interesting.
Overall, I am very happy with the results and also the fact that the tap handle which was rusted solid operated perfectly when removed from the bath 13 hours later with no negative effects observed.
This leads me on to an evil thought. What electrolyte could/would one use to chemically polish stainless steel? I got some fittings done once after I had fabricated them and the finish was brilliant, certainly not a mirror polish, but the electrolysis removed the scale and discolouration off the weld without leaving the washed out look that pickling paste, (hydrofluoric and nitric acid I believe) gives. I would love to be able to perform this in house and hopefully avoid the use of pickling paste where I can.

BobL
27th Sep 2018, 05:34 PM
If it was hydrofluoric I would leave it well alone. That stuff permeates skin, fat and muscle to give you a bad burn and doesn't stop until it hits something with Ca in it like bone and then turns it to jelly.

I have heard of an electrochemical cleaning formula for SS that use salt, and H2SO4, HCl, HNO3 acids, and another one is HCl, HNO3 and H3PO4, usually done at elevated temperatures for short period or risk serious etching. The solutions are usually quite concentrated and viscous.

My understanding is the workpiece is the opposite to rust removal ie with and put onto the anode (+). The polishing process removes ~50 microns of SS from the surface and levels peaks and valleys.

Because concentrated acid baths are inherently dangerous and expensive especially for large objects, portable units that use concentrated citric acid painted on using a carbon fibre brush connected to a high current power supply and the work at ground are increasingly being used. The electrical discharge heats the acid and dissolves the scale etc. Commercial units are available but have also seen you tube vids showing a welder being used as a power supply. I have been meaning to try this for some time.

Karl Robbers
27th Sep 2018, 05:42 PM
If it was hydrofluoric I would leave it well alone. That stuff permeates skin, fat and muscle to give you a bad burn and doesn't stop until it hits something with Ca in it like bone and then turns it to jelly.
That's why I want to avoid the use of pickling paste where possible. I use chemical gloves and a full face shield whenever I use the stuff and I still don't like it!


I have heard of an electrochemical cleaning formula for SS that use salt, and H2SO4, HCl, HNO3 acids, and another one is HCl, HNO3 and H3PO4, usually done at elevated temperatures for short period or risk serious etching. The solutions are usually quite concentrated and viscous.

My understanding is the workpiece is the opposite to rust removal ie with and put onto the anode (+). The polishing process removes ~50 microns of SS from the surface and levels peaks and valleys.

Because concentrated acid baths are inherently dangerous and expensive especially for large objects, portable units that use concentrated citric acid painted on using a carbon fibre brush connected to a high current power supply and the work at ground are increasingly being used. The electrical discharge heats the acid and dissolves the scale etc. Commercial units are available but have also seen you tube vids showing a welder being used as a power supply. I have been meaning to try this for some time.

When we had the work done some time ago, the local electroplater couldn't have been less interested, so we enlisted the services of a carburettor rebuilder of all things. He had a smallish setup for plating carbys and using a different solution was able to electropolish our stainless bits. Not being the boss, I never did find out what was used.
More research required.

BobL
27th Sep 2018, 05:55 PM
When we had the work done some time ago, the local electroplater couldn't have been less interested, so we enlisted the services of a carburettor rebuilder of all things. He had a smallish setup for plating carbys and using a different solution was able to electropolish our stainless bits. Not being the boss, I never did find out what was used.
More research required.

Why don't you put a Scotchbrite cleaned piece of SS into your electrolysis bath and see what happens - remember it has to go on the + terminal side.
Normally its done with warm-hot (75ºC) bath but it only takes minutes using the conc acid baths but it might still work albeit much slower at room temp and with the foot bath salts electrolyte.

BTW I've ordered some carbon Fibre brushes to try the paint on method.

kwijibo99
27th Sep 2018, 06:21 PM
It's been a while since I used it and I'm not at home at the moment to verify, but a method I got of the interweb a few years ago for cleaning stainless welds used a solution made up of phosphoric acid and ethelyne glycol (rust eater and antifreeze).
To use, clip one lead of your battery charger to the piece to be cleaned and a balled up piece of clean rag (say 20mm diameter) to the other lead. Dip the rag into the solution so it's saturated then slowly rub it back and forth over the area to be cleaned. It gets quite warm and may crackle a little bit but after a few passes the welds come up a lot cleaner.
Unfortunately I can't remember the ratio of the solution or the polarity of the connections but the chemicals involved are fairly innocuous and it achieved the results I was after.
If you search google or YouTube for electro cleaning stainless steel, you should be able to find more info. I believe there are commercially available kits for this with conductive brushes etc but for the occasional one off job this process worked pretty well.
Apologies for the vagueness but hopefully this might point you in the rough direction of a solution.
Cheers,
Greg.

BobL
27th Sep 2018, 07:27 PM
It's been a while since I used it and I'm not at home at the moment to verify, but a method I got of the interweb a few years ago for cleaning stainless welds used a solution made up of phosphoric acid and ethelyne glycol (rust eater and antifreeze).
To use, clip one lead of your battery charger to the piece to be cleaned and a balled up piece of clean rag )say 20mm diameter) to the other lead. Dip the rag into the solution so it's saturated then slowly rub it back and forth over the area to be cleaned. It gets quite warm and may crackle a little bit but after a few passes the welds come up a lot cleaner. .

This is more or less the method I described above using a carbon fibre brush and citric acid. When I get my brush I'll give it a crack.

Sparksy
22nd Jul 2019, 12:11 PM
What electrolyte could/would one use to chemically polish stainless steel? I got some fittings done once after I had fabricated them and the finish was brilliant, certainly not a mirror polish, but the electrolysis removed the scale and discolouration off the weld without leaving the washed out look that pickling paste, (hydrofluoric and nitric acid I believe) gives. I would love to be able to perform this in house and hopefully avoid the use of pickling paste where I can.

Citric acid or oxylic acid. Citric is better as its food grade. Used to use it to electro-polish smallish stainless parts when i worked in food industry. A lot safer than pickling paste. Avoid using stainless as the anode releases cadmium. use carbon rods or welding supply places sell carbon brushes for similar purpose.

Pumpkinate
22nd Jul 2019, 04:59 PM
I've also had great results with rust removal using basically the set up in the first post.

Has anyone tried electrolysis for removal of mill scale from mild steel?