Tank Cleaning - Electrolysis or Muratic Acid

Using battery charger & Arm & Hammer washing soda & zinc plate steel rod for anode...

I hooked it up & turned on the charger...when I hook the voltmeter, I am getting a reading -.45 volts......it is a brand new battery charger...set to 12 amp..... Am I doing anything wrong......doesnt seem to cleaning it very well after 4 hours......

I am resort to water & muratic acid to clean..... what % muratic acid to water ?????

Any suggestions......?????

Local radiator shop wants $ 60 to clean with muratic acid....might have to do that route on Monday if no success on my own.....


Tank inside is heavy rust & gas residue.....


Thanks in advance

 

Some good battery chargers are "smart" so they won't produce current unless they see some battery voltage. That could be your problem.

I've used phosphoric acid (1 gallon about $12 in the paint department of Home Depot) with good results. You can use it straight or dilute it. The more you dilute it the longer it will take. If the tank is really rusty I'd use the full gallon and dilute with water until the tank is full. Keep the cap off as it needs to vent. Of course check it regularly so you don't leave acid working on the tank after the rust is gone.

 

+1. Just did my second tank with phosphoric acid, came out great. Did pretty much what Carl said above, except: I used the whole gallon, closed up the tank and shook it around real good, let it sit first on one side then the other for about 10 min each, upside down for 10 min, etc; then added enough water to fill it up and let it sit for about an hour, with the top open.

Flushed out thoroughly, blew as dry as possible with compressed air and immediately dumped in a mixture of SeaFoam, 30W motor oil and gasoline, closed up the tank and shook that all over inside.

BTW, I use that super-sticky stiff aluminum furnace tape to close up the petcock and cap openings; its adhesive is quite resistant to even most solvents. Gas softens it but it takes a while.

 

+1 to the phosphoric, muriatric will flash rust VERY quickly

fitz, love the seafoam/oil/gas cocktail....great idea

 

I believe you are right....this is a smart battery charger......I dont think any current was being sent thru to the rod......thats why it did absolutely nothing......

what is your disposal method then of the water & phosphoric acid....????

 

im sure you were doing it right just in case here are the instructions i downloaded hope it works im afraid of the other methods just because i know i will get it on the paint some how with my luck

Electrolysis is a technique for returning surface rust to iron. The process actually alters the tank wall on the molecular level removing the oxygen that has oxidized (rusted) the tank. This method has advantages over old standbys like vinegar, Coke, muriatic acid, naval jelly, wire brushing, sand blasting, etc. because those methods all remove material to get rid of rust. These other methods also remove un-rusted material. The electrolytic method removes only the oxygen from the oxidized metal by returning surface rust to metallic iron, rust scale is loosened and can be easily removed. Un-rusted metal is not affected in any way.

What do you need to make this work? Not much, really:

* Your rusted gas tank.
* A battery charger or other source of 12V DC power.
* Wires or cables to connect the electrodes together, lLower guage better, less heat. make sure it insulated.
* Sacrificial electrodes - iron re-bar works great, stainless steel is very bad (and the result is illegal and dangerous). Go to your hardware store get some non coated steel
* Arm & Hammer LAUNDRY Soda, also known as washing soda.
* Some chains or steel wire to suspend the part in the solution - copper wire is bad and messy.
* Water

The basics are pretty simple.

1. Look in your tank. Get familiar with the inside of your tank you are going to need to fit the Sacrificial anodes in there and have them not touch the edge, because it will cause you to ground out and not work.
2. Mix 1 Tablespoon of Baking Soda with every gallon of water to create an Electrolyte solution. (Don't go overboard with the baking soda people. It won't help.)
3. Cut your sacrificial anodes to lengths that will fit in the tank. I drilled holes at the top to attach a wire. Now use electrical tape to tape the wired end and the other end thickly so there is no possible way you can ground out on the edge. You can use more then one at a time.
4. Wire all of the electrodes together so they are, electrically speaking, one big electrode. Make sure all connections are on clean metal and sufficiently tight to work.
5. Suspend your part in the solution using the wire/chains so it is not touching the bottom and is not touching any electrodes.
6. Attach the battery charger NEGATIVE lead to the part and the POSITIVE lead to the electrodes. Do not get this backwards! If you do, you'll use metal from your part to de-rust your electrodes instead of the other way around -the positive electrodes are sacrificial and will erode over time. That's how the water becomes iron-rich. THE POLARITY IS CRUCIAL!! The iron or stainless electrode is connected to the positive (red) terminal. The object being cleaned, to the negative(black). Submerge the object, making sure you have good contact, which can be difficult with heavily rusted objects. Get it backwards and your object will be relentlessly eaten away! Make connections on a part of your electrode that protrudes out of the solution, or your clamps will erode rapidly.
7. Double check everything to be sure the right things are touching, the wrong things are not touching, and the cables are hooked up correctly.
8. Turn on the power - plug in the charger and turn it on.

Within seconds you should see a large volume of tiny bubbles in the solution - these bubbles are oxygen and hydrogen (very flammable!). The rust and gunk will bubble up to the top and form a gunky layer there. More gunk will form on the electrodes - after some amount of use, they will need to be cleaned and/or replaced - the electrodes give up metal over time. That's why re-bar is such a nice choice - it's cheap and easy to get in pre-cut lengths.

The process is self-halting - when there is no more rust to remove, the reaction stops. This is handy because you don't have to monitor it, and because you can do large parts where they are not totally submersed at one time (aka, by rotating them and doing half at a time) without worrying about "lines" in the final part.

Once you are done, the part should immediately be final cleaned and painted - the part is very susceptible to surface rust after being removed from the solution. There will be a fine layer of black on the part that can be easily removed, and once it is removed, the part can be primed/painted as needed.

Safety Precautions
You're playing with serious stuff here, so stay safe. It's not rocket science, but if you're new to this, you might not know all of this - so read up before you do any of this.

* This process produces highly flammable and explosive hydrogen gas (remember the Hindenburg?), so do it outside, or in some other well ventilated area. Hydrogen is lighter than air (like natural gas), so it will collect near the ceiling - not sink to the floor like some other flammable vapors will (like propane and gasoline). If you have open flames near this (Hint: gas appliances like water heaters and furnaces have pilot lights!) you will most likely severely injure or kill yourself (and others near you) and become a contender for the Darwin Awards in the process.
* Assuming you used re-bar and steel wire/chain like you were told to, the waste water resulting from this is iron-rich - it's perfectly safe to pour it out onto the grass and your lawn will love it. Beware of ornamental shrubs that don't like iron-rich soil though, unless you like making your wife mad at you.
* Make sure the battery charger (or whatever source of power you use) stays dry. All of the usual cautions about any electrical device in a wet environment apply here.
* The solution is electrically "live" - it is a conductor in this system. Turn off the power before making adjustments or sticking your hands into the solution. You can get a mild shock if you stick your hands into the water with the power on.
* The solution is fairly alkaline and will irritate your skin and eyes. Use gloves and eye protection. Immediately wash off any part of your body the solution comes into contact with with plenty of fresh water.
* Don't use stainless steel for the electrodes. The results are toxic and illegal to dump out.
* Don't use copper for the electrodes and anything else in the water - the results are messy.

If you are unsure of any of this or unsure about your safety - STOP! Get help before you do something stupid. Use common sense, be smart about what you're doing, and stay safe so you can finish your restoration project and enjoy it

 

Smart charger is probably the problem... I used an old 1.5A trickle charger and it worked fine.... maybe hit a few yard sales looing for an older style

 

Just went to Sears & bought a manual battery charger...it will not shut off until you pull the plug.....the smart chargers dont seemed to ever kick on & power up....

 

for those using acid...what do you do with it after you are finished, and where can I get directions on using the electrolysis method? I'm not dumping any sort of acid on my property.

 

3 posts up is instructions on electrolysis method. or google it electrolysis rust removal

 

Micarl,

What is the exact product that you found in the dept at Home Depot. Please specify.....

I can not find anything that had phosphoric acid in it in that dept....

Went over to the concrete dept & found Sikagard Concrete Heavy Duty Clean & Etch - 1 gallon for about $16.00....contains water, phosphoric acid & nitric acid....

I have not tried it yet....

 

Back to Electrolysis method.....using 3/8 rebar for anode.....Arm & Hammer Washing soda......& a manual battery charger...have about 11 volts at anode using 10 amp rate......I will check after about 3 hours to see how it looks.....

5ofakind

 

I don't recall the brand. I'll have to look tomorrow at the shop. The jug has a rectangular base rather than round (sort of like an antifreeze bottle).

 

Started the electrolysis method......nice rust color after 4 hrs......I will have to repeat the process several times......besides the rust, will the heavy gas residue come off as well......

Also, I was thinking of using a muratic acid solution as a final step......

What percentage solution ???? 20% - 1 part acid to 4 parts water ???

Any thoughts.....I know it will etch & create flash rustng as well....but can take care of flash rusting by washing out & coating with Marvel Mystery oil ....

Any thoughts or suggestions is welcomed...

 

Does anything know the percentage solution for water & muratic acid for tank cleaning ???

Does 20% sound about right ????

I know for etching a swimming pool with heavy algae is 20 %.......so does 20% for tank cleaning sound about right...?????

 

HERE is the stuff I got at Home Depot.

 

http://xjbikes.com/Forums/viewtopic/t=11733.html

http://www.xjbikes.com/Forums/viewtopic ... iatic.html

 

http://www.altelco.net/~jacil/clay/moto ... Setup.html