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Shadow Research Center
by Richard Angelico
The process I use is the result of researching a lot of different methods, speaking with experts who clean artillery shells and combining a few different techniques into one that I find is clean, efficient and safe.
To begin with, electrolysis cleans metal by placing an electrical charge between the solid surface of the item being cleaned and the rust or corrosion coating it. The electrical charge removes this oxidized coating. I have also been told the use of electrolysis helps drive moisture as well as salt from the inside of objects being cleaned and it returns carbonized metal not oxidized to solid iron. Not being a chemist or engineer I cannot speak to that but accept it.
When I first dig an iron object like artillery shells or fragments, I place them in a bucket and cover them with hot water. I have a hot water line in my back yard that I ran for this purpose. This prevents the iron from drying out , cracking or scaling , helps begin the cleaning process and flushes out salt from the metal. I do this several times, brushing the iron items with a metal brush between soakings until all of the dirt and most of the loose rust or scale comes off. DO NOT hit the iron relic HARD with a hammer or any metal object attempting to knock off rust or corrosion. Iron right out of the ground, particularly damp or wet ground is fragile and striking it with a hard metal object will fracture it. A gentle tap on loose scale at an angle to the relic surface is O.K.
While the iron is soaking you can gather the rest of the equipment you need and set it up. Hereís what to get and how to do it:
1.) A battery charger with a 6 volt/12 volt switch and an amperage switch with a 2amp/6 amp position and a manual charge position switch. These are hard to find. I could find a 6 volt/2 amp combination but had to buy a second charger to get a 6 volt/6 amp setting. You will use the 6volt/2 amp setting for normal cleaning and the 6 volts/6 amps setting for initial cleaning of heavily encrusted iron.
OR a professional power supply that controls amps and voltage and provides a steady stream of power instead of the "pulsing" a battery charger provides. This is optimum, I have one but they are expensive .
2.)A tank for the electrolysis process. I use several, depending on the size of what I am cleaning. Sometimes a five gallon bucket , a Rubber Maid type kitty litter pan, or a Rubber Maid storage box, etc. You get the idea.
3.) An electrolyte. After much trial and error I use plain old Arm and Hammer Baking Soda. It is safer, cleaner and cheaper than lye and I think it works just as well. I use 1 tablespoon per gallon and then increase it if I do not get electrolytic action...but the amount does not appear to be critical to the process.
4.) An Anode. The anode is what cleans your iron object. It is connected to the POSITIVE clamp on the battery charger. I use 316 stainless steel sheet metal about 1/16 thick. I get this at stainless steel fabricating shops off of their junk piles. Some shops will give it to you others will sell it. It is not overly expensive. It should be as long as your container and wide enough to stick up out of the water solution. I find the larger the surface the better the cleaning process goes.
You can also use 1/8 or 1/4 mild steel plate but it is not as efficient as stainless steel. I get the plate from trash piles at welding shops. It needs to be cleaned before you use it, not rusty. A wire brush or sandpaper works fine, sand blasting works better if you have access to a blasting cabinet. Again, the steel plate works but not as well as stainless.
5.) A Drill Press . I use this to drill a 7/64'th hole in Cannon balls or fragments , then tap the hole ( thread it) with a 6/32 tap. Sounds complicated but itís a snap. You get the drill and tap set at Home Depot. Use machine oil when you drill the hole in the iron and use it again when you thread the hole. Do not force the tap when trying to thread the hole, it will snap off. If it is hard to turn, back it out clean out the hole put in more oil and slowly thread it again. Easy does it. Clean the oil out of the hole. Next I screw into the hole a 6/32 brass bolt of what ever length I require. ( easy does it here as well, brass bolts snap off easily) This makes a good solid metal to metal contact which is critical to electrolysis. You can also use a longer bolt and put a wing nut on it and a regular nut below it. Screw the bolt into the shell and then attach the wire to the bolt between the wing nut and the regular nut and tighten. This makes it easier to disconnect so you can take the shell out and check it from time to time. To this bolt or a copper wire leading from it ( preferably a wire) I connect the NEGATIVE clamp from the battery charger. If the item you are cleaning can simply be clamped with the NEGATIVE LEAD then of course you do not have to tap a hole, just attach the clamp to it. The NEGATIVE clamp can be in the water, it doesnít hurt it. ( However, if lye is used as an electrolyte , it will eat it up.)
If you are cleaning other types of iron: axe heads, horse shoes, old iron tools connect a clamp to the copper wire to clamp onto the iron object. This can be something as small as an alligator clip, to the galvanized claps you find in hardware stores or the replacement battery clamps you find at auto supply stores. Clamp your battery charger lead to the end of the copper wire.
6.) Mix up your electrolyte, enough to cover the item being cleaned by a couple of inches. Place the Relic in the water/electrolyte, attach the negative lead to it. Place the anode in the water. Make sure more than enough is sticking out of the water to attach your POSITIVE clamp to it. Make sure the Anode and the relic DO NOT TOUCH and are separated by several inches.
7.) Plug in the charger. In a few seconds you should see bubbles coming from the relic you are trying to clean. (You do not want rolling bubbles like alka seltzer. If it is bubbling like that you can slow it down by raising the anode up out of the water a bit. I use a brick to do this) Bubbles mean it is working properly and you have a good connection. No bubbles , bad connection, double check all connections again. On cast iron items like cannonballs it is better to clean them slowly. Just a few bubbles coming off, donít rush it. Actually the slower the better. With baking soda sometimes the Anode will bubble a bit but this is no problem....AS LONG AS THE POSITIVE CLAMP IS CONNECTED TO THE ANODE AND NEGATIVE CLAMP IS CONNECTED TO THE RELIC...OTHERWISE YOU WILL CLEAN YOUR ANODE AND DESTROY YOUR RELIC.
8.) Check on the process. After a few hours or overnight, check the relic. FIRST..unplug the charger. Take out the relic. If it was heavily encrusted, some rust or scale should "eggshell" off. Brush it with a stiff bristled brush or a wire brush. A lot of "black stuff" should begin coming off along with some scale and rust. Next rinse it with clean water. If it looks like it needs more cleaning, it probably does so put it back for more treatment. DO NOT attempt to force any lumps of corrosion or rust off by hitting it. This will often lead to damaging your relic, I know because I have done it much to my regret. Keep taking it out and cleaning it from time to time until it looks O.K.
9.) After it is clean ( Sometimes it takes a few days , sometimes a year) from electrolysis. I use detergent and a regular scrub brush followed by a brass bristled brush for a final cleaning. I find a brass brush cleans the iron better after it has been through electrolysis and you wont risk scoring the metal.
10.) Salt Purge. If the iron I am cleaning came from a salt marsh or salty area. You may need to leave it in the tank up to a year to a year and a half to get all the chlorides out. Check it frequently to make sure it is not losing surface metal. Next, I boil it for a few hours for a final purging. Let the water cool, change it and boil it some more. I do this four or five times. This helps get any remaining chlorides out.
All of the iron I dig from salty areas I let soak in hot water for a while PRIOR to electrolysis, changing the water frequently.
11.) Final Drying. If I have a solid iron ball or fragment I occasionally put the relic in the oven at about 350 degrees and bake it 24 to 48 hours or longer depending on its size. After taking it out of the oven and it is cool enough to handle. I dry brush it again with a brass bristled brush to remove any surface rust. Even if you do not see it, it IS there. You will notice the difference after you brush it.
DO NOT PUT A LIVE SHELL IN THE OVEN. DO NOT PUT A SHELL WITH A LEAD SABOT, OR CASE SHOT IN THE OVEN. LIVE SHELLS EXPLODE, LEAD MELTS.
An alternative drying method OR If the artillery shells have been in damp or salty soil you should also soak it in alcohol and then acetone. Let it soak for an hour in alcohol and take it out. The alcohol attaches to any water molecules and evaporates the water from the metal. Repeat this about 4 times and then repeat the process with acetone. Acetone neutralizes chlorides and also attaches to water molecules. This will get all the water out of the cast iron.
Both alcohol and acetone neutralize salts and chlorides which will eventually destroy your iron relic if not treated properly.
12.) Next you need to get some tannic acid powder. You mix this with alcohol and paint the shell with it several times until the iron is uniformly black. It is like painting with black alcohol, very watery, so watch how you load your brush or you will get this stuff all over. It can be messy if you are not careful and it stains everything it touches. Tannic acid halts and prevents any further rusting. It is the active ingredient in products like Rust Converter. You get Tannic Acid from a chemical supply house or search the internet for a supplier. If you are desperate, use Rust Converter. It will work but, in my opinion, it is not as good.
13.) Final Coating for metals: The tannic acid will dry pretty quick but I usually let the final coat dry overnight. Next, paint the shell with satin polyurethane varnish. I use two to three thin coats. This will seal the shell and keep oxygen away which is the arch enemy of old iron artillery shells.
14.) This is a rather inexact process...soemtimes when you think the shall has been cleaned perfectly and all the chlorides are out they arenít and you will begin to see rusting or flaking on the cleaned item. Donít panic...put it back in the electrolysis tank for a month or so and repeat the process.
I tell everyone finding shells is the easy part, cleaning them is the real work. It is like having a second job, very time consuming.
Of course there are a number of variations to this process and Iíll mention a few here. Some people use copper pipe as an anode. While this works extremely well, removes all rust and is very, very conductive, in my experience it tends to add too much of a copper color to the iron and the copper anode requires frequent cleaning to work efficiently. Some experts also maintain that copper anodes deposit a copper oxide on the object being cleaned and actually promotes further rusting after the object is cleaned. I have found this to be true, so I recommend avoiding the use of a copper anode. OPTIMUM ANODE: 316 STAINLESS STEEL.
DISARMING EXPLOSIVE SHELLS
YOU CAN DO THIS YOURSELF WITH A LITTLE RESEARCH BUT IT IS BEST LEFT TO A PROFESSIONAL. THERE ARE QUITE A FEW FOLKS WHO DO IT.
A SHELL DOES NOT HAVE TO BE DISARMED TO GO THROUGH THE ELECTROLYSIS PROCESS. YOU CAN DISARM IT BEFORE OR AFTER ELECTROLYSIS.
CLEANING MORE THAN ONE ITEM AT ONCE
You can do this by placing an appropriate length of 3/4 or Ĺ inch copper pipe across the top of your tank...NOT IN THE WATER.
You drill 4 holes in the pipe for 1 and Ĺ inch 10-24 stainless bolts, place the bolts thru the holes, use a nut on the other side to tighten it and add a wing nut which will be used to tighten down a lead to the tank. The leads I make from cg 84 black coated stranded copper wire. I strip both ends and attach ring terminals to each end. You Can also use "U" or spade connectors. You get these at most hardware stores in packs of eight I use the ones marked 12-10 awg for an 8-10 stud. Attach copper wire to the bolts using the ring terminals. Tighten the wing nuts up for a good connection, attach the wires to the relics in the tank using your 6/32 brass bolts. Put a wing nut on the bolt. Slip on the ring terminal , add a 6/32 net but do not tighten yet. Screw the bolt into the relic and then tighten the wing nut on the ring terminal. Next connect the NEGATIVE LEAD CLAMP of the battery charger to the copper pipe. On my anode I drill a hole thru the stainless use a Ĺ inch 10-24 stainless pan head nut and bolt and connect a copper wire lead to it as well. I get the red coated 84 gauge wire for this side, or you can just spray the wire with red paint. On either end of this wire I connect spade terminals. Again you get these at hardware stores. Get the ones marked 12-10 awg for 8-10 studs. Attach the wire to the stainless steel anode and clamp the other end to the positive lead of your battery charger. Set your charger to 6 volts, 2 amps and plug it in. All the attached relics should begin bubbling. This is helpful when you have a bucket of fragments to clean. Keep in mind you can attach small or large clamps to the copper wires using the ring terminals to connect to the posts on the clamp, to clamp to iron relics you do not want to drill. You get these clamps at Sears auto supply, Wal Mart , hardware stores, etc.
MATERIALS LIST FOR 4 POST TANK USING A RUBBER MAID STORAGE BOX AS THE TANK. APPROXIMATE COST $30.00
1. ONE 4 FOOT LENGTH OF 3/4 OR Ĺ INCH COPPER PIPE.
2. FOUR 1 AND Ĺ INCH 10-24 STAINLESS PAN HEAD BOLTS FOR PIPE CONNECTION.
3. ONE Ĺ INCH 10-24 STAINLESS PAN HEAD BOLT FOR THE ANODE.
4. FIVE 10-24 STAINLESS NUTS AND 5 10-24 STAINLESS WING NUTS.
5. FOUR 10-24 STAINLESS WING NUTS.( I USE THE NUTS TO FASTEN THE BOLTS TO THE PIPE , THEN SLIP THE RING TERMINAL OVER THE BOLT AND CLAMP IT IN PLACE WITH THE WING NUT.)
6.12 FEET OF BLACK COATED 84 GAUGE STRANDED COPPER WIRE.
7.THREE FEET OF RED COATED 84 GAUGE STRANDED COPPER WIRE FOR ANODE CONNECTION OR SIMPLY SPRAY A RED SPOT ON A LENGTH OF BLACK WIRE.
8.1 8 PACK OF RING TERMINALS MARKED 12-10 AWG , 8 TO 10 STUD.
9. 1 PACK OF SPADE TERMINALS MARKED 12-10 AWG, 8 TO 10 STUD.
10. ONE TWO PACK OF APPROPRIATE SIZED CLAMPS WITH SCREW POST CONNECTORS. THESE CLAMPS COME IN VARIOUS SIZES.
11. 1 7/64 METAL DRILL BIT.
12. 1 6/32 TAP.
13. 1 TAP WRENCH.
14. FOUR 1 3/4, 6/32 BRASS BOLTS.
15. FOUR 6/32 BRASS NUTS.
16. FOUR 6/32 BRASS OR STAINLESS WING NUTS.
11. ONE RUBBER MAID STORAGE CONTAINER FOR THE TANK
12. ONE LARGE BOX OF ARM AND HAMMER BAKING SODA.
I am not an engineer or chemist and although I have read a lot about electrolysis there is still a lot I have to learn, especially about the effects of voltage and amperage.
I am sure this process is not the final word on the "how to" aspects of electrolysis, in fact it is a work in progress and I have changed a few of the instructions over the past year or so based on experience and results, but it is a system that has worked successfully for Hy and me in cleaning dozens of iron relics.