Electrolysis - Anode Bubbling?

[Jim_M]

I am fairly new to restoring cast iron, but I set up an electrolysis tank and successfully cleaned a number of pans. When I tried using it to clean a Favorite #3 pan I noticed something different. My sacrificial metal (anode) was bubbling instead of the pan. I let it run for a day. When I pulled the pan out it was ruined. It seemed to have pulled a layer of the metal off. Yes, the positive terminal was connected to the anode and the negative to the pan. I used the exact setup that successfully cleaned several pans. After this happened, I changed the solution and the anodes. The next pan I cleaned with it came out fine (pan bubbling). I just tried another pan and now the pan AND the anode are bubbling. I don’t want to ruin another pan. Is the anode (sacrificial piece) supposes to bubble? What might have gone wrong on the pan I ruined?

Thanks
Jim

 

[Doug D.]

A photo of your setup may be more helpful before making several in-the-dark guesses.

 

[Jim_M]

Sure. Washing Soda solution. Two large iron plates (connected together with red battery cable. Charger set as it is in photo.

Charger set to 12 volt, manual, 12 amp.

Thanks
Jim

 

[Ben J]

I'm no expert with cleaning cast iron this way but I have done 5 or 6 different pans. I use it to de-rust tools. My setup is two pieces of number 4 rebar in opposite corners and I use a 12 volt 6 amp power supply (because that's what I have) for most things but I have used my 12 volt, 10 amp, 35 year old battery charger. Everything fizzes in my tank which is a 14 gallon trash can. I see no difference between 10 amps and 6 amps.

 

[Doug D.]

Nothing seems amiss in the photos, as far as I can tell. There shouldn't be the fizzing halo of bubbles from the anode like that which emanates from the pan, although bubbles produced from the pan might adhere to the anode. We'll have to assume the charger can't spontaneously change polarity. The question remains why has it worked successfully in the past and then not. Not sure what else could affect the circuit, assuming nothing is touching anything else it shouldn't be.

 

[Ed Grabski]

I would try another charger to start.
These chargers don't cost very much to build and are not what you would call Heavy Duty.

I have a real DC power supply and most of the cheaper chargers just clip the negative part of the AC, at least that's what they used to do.

 

[TStamp]

Was your pan touching your sacrificial anode? I have had the anode bubbling also in my e-tank also, I used a 5 gallon paint stick to make sure there was no contact between the two, found the two were touching. Now before turning on the Battery charger, I run the stick around the inside of the tank to verify there is no contact between the two.
Hope this helps.

 

[Jim_M]

No, they were not touching. I even rested the pan on a silicone trivet. I thought maybe rust debris on the bottom of my tank was causing a connection.

I am going to try swapping out the power supply.

Jim

 

[Jim_M]

I swapped out the power supply with a converted computer power supply. Still the same results. The anode (sacrificial piece) and the pan are both bubbling.

I tried using a piece of rebar as the anode, same result.

After a lengthy search of the internet, I found this page:
https://antique-engines.com/electrol-details.asp. It seems to be a reasonable explanation of the electrolysis / rust removal process. It says hydrogen bubbles form at the cathode (piece being restored) and oxygen bubbles form at the anode (sacrificial piece).

My power supply is now cranking 13 Amps. Could others who have higher amp systems check their anode for bubble formation?

If this is ‘normal’, it still doesn’t explain why one of my pans got ruined in the electrolysis tank.

I am going to try to de-rust some less valuable pans and see what happens.

Any comments would be appreciated.

Thanks,
Jim