Author Topic: What voltage works best for electrolysis?  (Read 6641 times)

Fusion_power

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Re: What voltage works best for electrolysis?
« Reply #20 on: November 06, 2005, 10:11:26 PM »
Perry,

I dug the part about contaminants up in an electrolysis document I found searching the web.  A synopsis is that contaminants in the water can damage the  item being cleaned or the metal sheet used as a cathode.  The most common contaminant is chlorine from salt but also present in many water sources.  Also, excess minerals in the water can impede the reaction.  Most well water and or water from streams would  have these dissolved minerals.

The best source of water would be distilled but the cost would be pretty high all things considered.  The next best choice would be a clean source of rainwater.  I have a metal roof and can just sit a drum under one of the valleys to catch all the rainwater I want.  For me, this is an easy solution but I do have to wait until it rains which fortunately is pretty regular here in the southeast.

There was also a recommendation to regularly replace the water as contaminants build up.  I would presume that the more you use it, the more buildup and therefore the more often the water should be changed.  Keep in mind that this was a document covering electrolytic cleaning of very high value antiques so they would do things with a bit more attention to detail.

There were lots of other recommendations such as making a "form fitting" cathode out of metal mesh to ensure even flow to all parts of the object being cleaned and varyinig the current flow over time using high current to remove heavy rust, then using lower current to get a smooth even finish.


Offline Ed Allspaugh

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Re: What voltage works best for electrolysis?
« Reply #21 on: November 06, 2005, 11:09:09 PM »
Quote
Perry,
water can damage the  item being cleaned or the metal sheet used as a cathode.  

 The Cathode, negative connection, is the skillet or piece being cleaned , the Anode, positive connection, is the metal sheet.
Gray Iron-- Old as antiquity, new as tomorrow.

Fusion_power

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Re: What voltage works best for electrolysis?
« Reply #22 on: November 15, 2005, 09:36:01 AM »
Ed,  You are correct, I transposed the Cathode and Anode above.


I finally solved one of the more difficult problems with cleaning cast iron.  Its not just a single solution, but rather a series of steps that can be followed.

1. Pre-treat in a lye bath to loosen and remove hydrocarbon based compounds. (2 or 3 days)
2. Scrub with stainless scouring pad to remove the crud and as much loose rust as possible.
3. Electrolysis bath the item and run it until the rust and remaining crud are loosened. (6 hrs or so, current dependent)
4. Scrub and rinse the item with the scouring pad until it is free of most external material.
5. Dry it on the stove and by wiping down with paper towels.  The water must be removed fast!
6. Wire brush the item until it has a smooth surface free of lumps and clumps of stuck on material.
7. Put it back in the electro bath and run for about an hour.  This will convert remaining rust particles to ferrous iron.
8. Scrub with scouring pad again and a bit of dawn detergent.
9. Rub down the item with white vinegar and continue rubbing all surfaces with paper towels to dissolve ferrous (black powdered) iron. (3 minutes!)
10. Rinse with water, immediately place in the lye bath to neutralize the vinegar, then scrub and dry on the stove.  Treat with oil or crisco.

The most difficult of the above steps to figure out was the vinegar wash to remove the ferrous iron from the surface.  I tried various methods of washing and could get most of the black stuff off but there was always a residue.  This is because a cast iron surface is not smooth at the microscopic level.  Its full of pits and imperfections that the black dust can hide in.  The vinegar dissolves and removes this dust.  Its very important to control the time vinegar is on a cast iron surface since it also eats away the iron.  If properly done, the iron will be nearly residue free and in very good condition to season.

Why go through all the above steps?  Well, the result is the best exterior condition I've been able to achieve.