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Electrolysis


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  #21  
Old 12-03-2002, 09:56:46 PM
Tom petrasic
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Default how you do this stuff.

i have read all the messages and dont under stand how you do it.do you simply put a rusty part conneted to a cable in a plastic bucket with a other cable end to a hub cap or something, what you put in the bucket,water?then turn on the battery charger,and presto rust gone.you bush it down in water and dip it in 3% acid solotion, if your not using water in your bucket or vat doesnt it make nassty gas,what you put in there?,what about the bucket plastic ,dont know help
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  #22  
Old 12-05-2002, 12:36:19 PM
Franz
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Default Re: how you do this stuff.

Go over to the Smokestack board and do a search for electrolosys. Ought to be about a hundred postings on the subject.

(Editor note: spell it electrolysis and electrolisis as well as electrolosys. Gad, I had to go to my dickshunary after seeing all those ways to spell it. Anyway, the search program can only find them if you spell it the same way the posts have them written.

The best way to search the Archive is to put in ELECTROL and search with that. It will then find all of the threads.


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  #23  
Old 12-05-2002, 01:02:47 PM
Orrin
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Default Re: how you do this stuff.

The "Electrolysis" Web site posted, below, is probably more than you want to know about electrolytic rust removal.

It's an awful lot of reading for such a simple process; but, I guess the CYA approach is needed in this day and age.

Here's something that's shorter:

http://www.stovebolt.com/techtips/rustremoval.htm

And this:

http://www.oldengine.org/members/billd/electrol.htm

I believe the above method recommends using re-bar for the waste electrode. That might be all right if you are using a small container, but re-bar doesn't have much surface area. If you're de-rusting something large, a big waste electrode is needed to speed up the process. Something that's about a square foot in size works nicely.

Let's see if I can boil the technique down to a few words (something I usually can't do).

A chemical reaction, such as iron turning to rust, takes place when electrons are taken from one atom (iron) by another atom (oxygen). Electricity also happens to be a matter of electrons. A movement of electrons along a conductor is an electrical current.

So, it is possible for electricity to cause chemical reactions. It can even force a reaction to go in reverse, such as, taking burned hydrogen (water) and converting it back to oxygen and hydrogen atoms.

Anyhow, the electrolytic rust removal process forces chemical reactions to take place. The net result is the loosening of rust off the base metal. I believe the Electrolysis Web site explains the reaction in more detail than most of us would like to know.

There are loads of electrolyis sites on the WWW. Just go to http://www.google.com/ and do a search for "electrolytic rust removal" Be sure to include the quotation marks, otherwise you'll get more "hits" than you'd like to deal with.

To answer your question, yes, there are gases produced, including flamable hydrogen. That's why I do my electrolysis outdoors. I throw a tarp over the vat (loosely) to keep out insects, leaves, etc.


Electrolysis
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  #24  
Old 12-05-2002, 01:13:29 PM
Orrin
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Default Re: how you do this stuff.

Here is another good site explaining electolytic rust removal.


Electrolysis Made Easy
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  #25  
Old 12-10-2002, 12:43:59 AM
Tom petrasic
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Default Re: how you do this stuff.

orrin that was great site,just what i wanted no technical mumbo jumbo im not going to understand, but still a few questions,what about chomeplateing on a part being derusted?he also talked about useing lye,but i guess the washing soda is better? do you use a tablespoon to the gallon or more?to keep it for rusting again you use a phos acid solutin is that right?then paint.great help again orrin.
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  #26  
Old 12-10-2002, 01:32:40 AM
Franz
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Default Re: how you do this stuff.

It may help if you think of electrolosys as an electroplating process, where you are plating the rust from your part to the waste anode. The rust moves off your part and on to the anode. As far as chrome plating, if the chrome is solid, electrolosys shouldn't effect it. If the chrome has underlying rust, the chrome may come off. After electrolosys, prevention of re rusting is accomplished by coating the part with something that will prevent oxygen from getting to the part, oil, paint, or something similar. The phosphoric acid process doesn't work unless rust is present. Phosphating is similar in nature to bluing on a gun. Phosphoric acid chemicly converts a rust layer (Iron Oxide) to Iron Phosphate. Iron Phosphate is a chemicly bonded layer that is impervious to rust formation. Phosphating will effect chrome. Phosphoric acid will eat aluminum.
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  #27  
Old 12-10-2002, 01:45:02 AM
Orrin
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Default Re: how you do this stuff.

I'm glad the site helped out.

I've not done much electrolytic de-rusting of chrome plated stuff, but this is what I found. The electrolysis will lift the chrome off wherever there was a rust blister, underneath. It ain't ever gonna "look like factory," afterwards.

As for the brew's recipe, it's not critical. I use a plastic 55-gallon drum for my operation. There's about 45 gallons of water in it. I dissolved a full box of Arm and Hammer washing soda and one can of Red Devil lye in it.

I have a recipe here that calls for a whole lot more washing soda, but the strength I use works well enough for me. I've had enough clues to tell me that a stronger mix will do a better job. Some day I'll experiment with a small part in a gallon of strong solution. By-the-way, this stronger recipe also uses a bit of water glass, too. So far, I haven't used the water glass.

Ospho or Metal Prep are mixtures of phosphoric acid and some kind of salts. This type of pre-treatment should be used instead of straight phosphoric acid before painting.

Why do I know? I did some rust removal with phosphoric acid and then let the item (a steel wheel) sit, unpainted. In a few days it had a horrid case of rust. Ospho or Metal Prep will do just the opposite. It will help prevent rust.

I've got loads of de-rusted stuff treated with Jasco's Metal Prep that has been sitting around here, unpainted, for years. There's not a spec of rust on it. Of course, our climate is dry. The situation might be different where it's wet and humid.

Just follow the directions on the Ospho (or Metal Prep) bottle.
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  #28  
Old 12-10-2002, 12:57:44 PM
Franz
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Default Re: how you do this stuff.

Orin, "water glass" is sodium silicate. Disolved in water, it is an excellent cleaner, and was once a primary ingredient in 409, and still is in a lot of cleaners. The big drawback is it will make glass look etched or sandblasted if left to dry on glass. Straight sodium silicate solution works well with an electrolytic process for cleaning and degreasing. It is NOT a good process to degrease old engines because the technique will remove the grease from an old dirty item, leaving behind the rest of the dirt in a form that resembles concrete. We used to use this process for precleaning gun parts prior to bluing to minimize contamination of bluing salts. Sodium silicate solution in a soak tank works well if followed by high pressure washing with water. So called STRONGER electrolyte solutions with greater concentrations of washing soda or lye mainly tend to lengthen the operating life of the solution. Contamination of the solution is the primary killer of electrolytic derusting.
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  #29  
Old 12-10-2002, 04:58:04 PM
Orrin
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Default Great information! Where...

Great information! Where do you purchase your water glass?

BTW, I knew that water glass was sodium silicate, but I hadn't known all the other good stuff in your post. Thank you.

As to the concentration (strength) of the solution, this is what I've observed:

Let's say there is a part that is too big to be totally submerged in the solution. In hot weather there will be evaporation at the surface; and, a concentration of dried washing soda will build up on the part being derusted, just above the water line.

I've noticed that under these "salts" there is not one iota of rust, crud, or black stuff that has to be wire-brushed off. It's clean, bare metal.

You can see why I'm thinking that a very strong solution may act differently.

BTW, according to the recipe I have that uses water glass, it would take a huge amount of washing soda for my 55-gallon vat. That's why I've never tried it.

Speaking of de-greasing, I've found that I can throw a gunky, greasy, messy, item into the vat and the bubble formed during electrolysis will lift it right off. The thing will come out clean as a whistle. The lye helps this action.

Electrolysis will lift paint, too. It comes off in big sheets if a bit of the solution can start to work underneath. Good paint jobs are a bit more stubborn. Again, lye in the solution helps with the paint removal.
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  #30  
Old 12-15-2002, 08:22:55 PM
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Harry Harry is offline
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Default Re: Phosphoric Acid

Just an update on the phosphoric acid. I picked it up at Home Depot and the brand name is PH-OSPHO-RIC Plus+ and the cost was $13.75 per gallon. 766520090104 (Everything needs a bar code these days. We'll have one tatooed on us some day.)

I brush it on straight from the jug, poured into a plastic cup. Don't use a coffee can to paint from because what you leave in the can will eat through.

When you brush it on, it fizzes and bubbles a bit. Then I wipe off all excess with a paper towel so the white crap doesn't build up. When it dries, you have a nice pickeled finish for painting.
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  #31  
Old 12-16-2002, 01:12:38 AM
Franz
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Default Re: Phosphoric Acid

Harry, what's the concentration on that acid?
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  #32  
Old 12-18-2002, 09:52:30 PM
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Default Re: Phosphoric Acid

I looked on the jug, but all it says is to use it straight from the jug. I take it that because I said it fizzled when I brushed it on, you think it's a bit strong?

I'll say one thing, it gives a great pickeled finish.
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  #33  
Old 12-19-2002, 01:41:12 PM
Franz
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Default Re: Phosphoric Acid

I was primarily just wondering about the concentration. There are several products used in the auto body industry that are also directly applied, as well as Gempler's 2 varietys of rust converters. I have the MSDS for both of Gempler's products, and the concentration is around the 5% level. If you get the MSDS for the product you bought it would be interesting to know if it contains either magnesium or zink. I buy mine at 85% concentration from the chemical company, and dilute it to around 4 - 5% because over the years I've found that to be the best concentration. I've also found wet time to be very important to the overall process, wet time allows for full penetration of the rust layer. I've even experimented with both electrolytic and heat speed enhancment to the process, and both offer advantages. Electrolytic use of Phosphoric can also disolve iron, so I recommend playing with some scrap first if you try.
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