Electrolytic Bore Rust Removal

[pcmacd]

OK. Call me clueless.

I've poked around here and can't find specific information on getting the rust out of my 8x58RD Gustaf barrel.

I understand how the electrolysis works, and have all the electronics needed to do such.

I guess I need some rubber test tube plugs for the breach, and a couple drilled thru for the sacrificial steel rod to keep it from shorting out on the barrel?

Somebody pint me in the right direction. This seems to make lots more sense, replenishing steel as rust in lieu of scraping it out of the bore?

tanks

[LAGS]

I remove rust from barrels using Washing Soda and a 12volt battery charger.
But , I mostly do the whole barrel not just the bore.
But I see no reason why you can't just put the Washing Soda mix in the bore.
But most Barrels that I have seen that someone tried to do just inside the bore , ended up getting liquid on the outside and ruining the finish in some way.
But the Kits they use to sell , did a good job on removing Fouling in the barrel , but rusted bores are a lot harder to do.
I also just soak the barrel in vinegar to remove rust.
But I plan to Reblue the rifles anyway.
So the vinegar removes the old Bluing too.
Adding a little Hydrogen peroxide to the vinegar mix makes it a little more potent.
But the metal will rust again once removed from the mix if you do not neturalize the vinegar with baking soda and water washing.

[akajun]

You can do it, plug the chamber, stick a rod down the bore, fill with solution, center it up top with an o ring, connect the charger and come back every few hrs to scrape off the crud , wire brush the bore, and repeat. FYI if it’s just built up fouling which can look a whole lot like rust the electrolytic process will work wonders. However if there is pitting, it will still be there and will still be sharp, you’ll never remove it or “ replenish” the steel.
With pitted bores I like to run a brush with ospho/naval jelly/phosphoric acid and let it sit in the bore for about 10-15 mins then flush with hot soapy water, then clean as normal. This will take the sharp edges off the pits that trap and hold fouling and will make the barrel foul less. You can also do a fire lapping session on the bore to smooth them out further.

[john.k]

You wont be replenishing anything ...the process simply lifts the oxide from the metal as a fine mud ,or anything else sticking onto the surface ......if you use a weak carbonate solution as electrolyte ,there is little possibility of corrosion of the bare steel......As mentioned ,when the rust is gone ,the pits may well have sharp edges .........Simple fact is the bore is ruined anyway ,all you are doing is removing the rust.....The chances of lifting a tight layer of metal fouling and finding a pristine surface underneath is about the same as winning the lotto.

[pcmacd]

262175262176262177262178262179262225262226

UPDATE: check the two new bore images, and see if you can tell which one was @beginning, and which one was after the third pass of electrolysis... these were taken in the same area, 12" from breach, 1 o'clock.

AND... I initially wondered why some parts of my anode rod were covered with crap and other parts were nearly clean? It is because when I would top off from the chamber from the breach, the solution would not pass the first o-ring! Duh. Now I am using only two o-rings in lieu of three.

~~~~~
I put a cork in the end of the 8x58RD Gustaf, put a 3/16" home despot well scoured steel rod down the tube with o rings to center it.

Put 20 Mule Team Borax at the rate of 1/2 teaspoon per pint into the bore, hit it with various power supplies.

The general setup shows the first power supply, but the other image is of a very serious instrument grade HP power supply capable of 50 volts and 10 amps.

30 volts and 5 amps made the rifle too hot to handle, so I toned it down to what you see here in the display window of the p/s. That's about 16 watts; volts x current (amps) = power (watts). 15 watts ain't much, it makes the barrel barely warm to the touch in a 95F garage.

It is extraordinary the amount of crap coming out of this bore. The first pass electrolyte looked like sewer sludge.

At the end of round one flushed it all out and could not tell the difference in the bore.

I observe it with my Teslong camera at a specific point and orientation every time so I can see changes. None yet.

This is round two. Barrel is still uncomfortably warm at 12 volts and 1.3 amps. That's only about 15 or 16 watts. Not much.

I'll let it run a while longer, rinse it out and WD40 the exterior, run some brushes down the bore and do it again overnight.

Its been running a few hours now and I know it is not going to burn down the house.

Thanks for all of your inputs.

I would never have thought to do this, as easy as it is to do?

This was just, oh so easy to do!

And further, I just cannot believe the amount of crap coming out of this bore.

Genius, y'all are! Why din't I think of this?????

~~~~~
Cranked it up to 30 volts and 3 amps, that's 90 watts of power. The barrel is getting pretty hot. If it starts spitting electrolyte out the breach I guess I'll tone it down.

Geez. Barrel is around 190F. I guess we will tone it down! Turn off for a few and blow a fan on it.

I can see no difference betwixt now with all of the fulminate coming out the breach and before I started, according to the Teslong camera.

~~~~~
p.s. a 12 volt battery charger would have done just as well as my fancy electronics; people even use wall warts from various electronic products they no longer have. It just might take a little longer if it does not have the current capability (current is energy flow...)

Get the o rings at Harbor Fright. Just the cheap set with a 3/16" Chinese steel rod from Home Despot works for an 8mm barrel.

[reivertom]

Keep us updated. I have a M1917 that has a dark bore I might try that in.

[ndnchf]

I used to do bore electrolysis. It works, but now I prefer to use Evaporust. It disolves the rust with absolutely no harm to the base metal.

[john.k]

If excessive power is used (see above) ,there is a likelyhood of plating a thick iron deposit onto the newly cleaned steel........this rough black deposit is notably hard to shift.Whats needed is fractional amps at 2-3 volts ,in the case of a bore.When operated within the correct parameters ,the fine hydrogen gas bubbles liberated under the non conducting rust or whatever ,lift the rust from the surface,without plating an adherent layer of iron ,which is obviously not wanted.

[owejia]

Evaporust good stuff, non toxic and cleans up with water. Firing walnut media shells through the bore after evaporust will give it a bright shiny bore.

[Chill Wills]

In the 1990's I made up one to pull lead out of the bore. Used it some. Works for sure but I wondered if and when it would start getting hungry for barrel steel.

[pcmacd]

If excessive power is used (see above) ,there is a likelyhood of plating a thick iron deposit onto the newly cleaned steel........this rough black deposit is notably hard to shift.Whats needed is fractional amps at 2-3 volts ,in the case of a bore.When operated within the correct parameters ,the fine hydrogen gas bubbles liberated under the non conducting rust or whatever ,lift the rust from the surface,without plating an adherent layer of iron ,which is obviously not wanted.

How is this possible with the current going FROM the barrel TO the anode rod?

[john.k]

Its actually a plating process .....in effect you are plating iron from the rod onto the steel bore......however ,due to unsuitable conditions ,the iron does not stick to the bore ,but remains as a black powder in the liquid (incidentally ,this is why beginner copperplating doesnt work.)....As a by product of the electrolysis of water ,hydrogen forms in tiny bubbles at the bore surface .......its a fact that the pressure in these tiny bubbles is great ,and they force off any impervious layer over the conducting bore surface.This can be rust ,fouling ,paint ...There are plenty of technical explanations of the electrolytic derusting process online ,no need to repeat it here.

[pcmacd]

Its actually a plating process .....in effect you are plating iron from the rod onto the steel bore......however ,due to unsuitable conditions ,the iron does not stick to the bore ,but remains as a black powder in the liquid (incidentally ,this is why beginner copperplating doesnt work.)....As a by product of the electrolysis of water ,hydrogen forms in tiny bubbles at the bore surface .......its a fact that the pressure in these tiny bubbles is great ,and they force off any impervious layer over the conducting bore surface.This can be rust ,fouling ,paint ...There are plenty of technical explanations of the electrolytic derusting process online ,no need to repeat it here.

Got it. Thanks.

Never gave a thought to the hydrogen bubbles helping to remove the rust.

[Mk42gunner]

I have not used electrolysis, but I have used Evaporust on a .308 barrel that looked worse than a fifty year old sewer pipe. The bore was rusty, not copper or lead fouled, the rifle had sat in a corner for a couple of years with a leak in the roof that was funneled right to it.

I taped the muzzle with electricians tape and filled the bore with a small funnel and let it sit overnight leaning up in the sink. It worked pretty well, still not spotless, but definitely shootable now.

Robert

[Scrounge]

Its actually a plating process .....in effect you are plating iron from the rod onto the steel bore......however ,due to unsuitable conditions ,the iron does not stick to the bore ,but remains as a black powder in the liquid (incidentally ,this is why beginner copperplating doesnt work.)....As a by product of the electrolysis of water ,hydrogen forms in tiny bubbles at the bore surface .......its a fact that the pressure in these tiny bubbles is great ,and they force off any impervious layer over the conducting bore surface.This can be rust ,fouling ,paint ...There are plenty of technical explanations of the electrolytic derusting process online ,no need to repeat it here.

If you use lower current, it will actually plate, according to some stuff I've read. Max a couple of hundred milliamps. Just don't hook it up backwards. It will eat the object you're trying to clean.

Though I'm also fond of EvapoRust.

[pcmacd]

Its actually a plating process .....in effect you are plating iron from the rod onto the steel bore......however ,due to unsuitable conditions ,the iron does not stick to the bore ,but remains as a black powder in the liquid (incidentally ,this is why beginner copperplating doesnt work.)....As a by product of the electrolysis of water ,hydrogen forms in tiny bubbles at the bore surface .......its a fact that the pressure in these tiny bubbles is great ,and they force off any impervious layer over the conducting bore surface.This can be rust ,fouling ,paint ...There are plenty of technical explanations of the electrolytic derusting process online ,no need to repeat it here.

Sir, I believe that the direction of the migration of metal is the direction of the current.

Thus, if the barrel is the cathode (negative, "-") then the sacrificial rod down the center is the anode (positive, or "+"), then the process is FROM the barrel TO the ROD.

After all, that IS where the rust migrates when freed from the bore - to the rod, or anode.

[BigEyeBob]

Correct.

[john.k]

If the "process " is from cathode (barrel surface) to the anode (rod) ,then why does the rod disappear?.....Its not as simple as thinking electric current goes "one way".......there is a great deal online about electroplating ,and electrolytic descaling processes,no point going over it here........But as mentioned ,reverse the process ,and you will have a smoothbore.....continue and the barrel disappears .

[pcmacd]

If the "process " is from cathode (barrel surface) to the anode (rod) ,then why does the rod disappear?.....Its not as simple as thinking electric current goes "one way".......there is a great deal online about electroplating ,and electrolytic descaling processes,no point going over it here........But as mentioned, reverse the process ,and you will have a smooth bore.....continue and the barrel disappears .

I've had scads of chemistry over the years (and am a degreed mechanical engineer, for whatever that's worth here), and the only thing I can imagine is that when the iron oxide or just iron ions hit the steel anode, they do other things to the anode when attaching to its surface.

I've scoured down the anode betwixt immersions to keep it conductive [methinks?] It is certainly rougher ever trip. The surface chemistry of the anode has w/o a doubt changed if judged by only color changes alone after the scouring with a Brillo is over and done.

I submit that the anode does not, however, give up material in the conventional sense. It might give up material when its surface combines with the incoming crap, and then we scour it off, but it cannot possibly give up material to the barrel, the cathode. From what I know about electrolysis that just ain't possible [but again, I ain't no ex-spurt here, just giving educated guesses!]

That's my best estimate, and I am fairly sure about my analysis. I don't mind being wrong here, friends, and I don't mean to be "holding forth."

I'm CERTAINLY not an ex-spurt on this subject [ex-spurt: somebody used to be a SPURT?]

The direction of the migration is, w/o a doubt, from the barrel to the "sacrificial" (that's what people call it, I believe it to be incorrect) anode. That is to say, from the NEGATIVE (-) pole to the POSITIVE (+) pole. That's how current runs, and I've no doubt that is how it carries ions (such as iron rust; not exactly ions, but you get the drift? No pun intended?) from place to place.

It makes sense that if one runs for too long or at too high a power level that one will take material from the lands and grooves, then place them on the anode.

When one is PLATING something, one runs a FROM SACRIFICIAL metal to the TARGET metal, and having absolutely no experience can hazard a guess that the SACRIFICIAL metal is to the (-) pole,and the target to the (+) pole.

Think about it?

As much electronics experience as I have, I still have to stop and scratch me 'head over this stuff. It's simple, but it is not.

I have learned a great deal from y'all here and thank you kindly.

[swheeler]

Sir, I believe that the direction of the migration of metal is the direction of the current.

Thus, if the barrel is the cathode (negative, "-") then the sacrificial rod down the center is the anode (positive, or "+"), then the process is FROM the barrel TO the ROD.

After all, that IS where the rust migrates when freed from the bore - to the rod, or anode.

I do believe this is backwards. Red+ to the barrel, Black - to the rod is how should be hooked up.https://video.search.yahoo.com/yhs/search?fr=yhs-pty-pty_news&hsimp=yhs-pty_news&hspart=pty&p=building+a+electric+gun+barrel+cleaner#id=2&vid=28e41b2322d110a04222de5af1400e32&action=viewhttps://video.search.yahoo.com/yhs/search?fr=yhs-pty-pty_news&hsimp=yhs-pty_news&hspart=pty&p=building+a+electric+gun+barrel+clea

I built this one decades ago, used it on many many milsurps and it does a fine job, hooks up and runs just like Foul Out III barrel is always the anode +, but I'm removing lead and copper, maybe some rust too.
https://i.imgur.com/KNZGH2I.jpghttps://i.imgur.com/1jhuTbJ.jpg

[blpenn66502]

Used to use this a lot with farm fresh tools. Negative (black) lead from battery charger goes to the item for de-rusting, red goes to the sacrificial anode (I always used a stainless steel pan lid).

Sent from my LG-H918 using Tapatalk

[Rapidrob]

I've been using this method for about 35 years now. I use an old computer power supply where the output can be adjustable from 5-14 VDC and several amps under load.
You want to avoid stainless steel rods like the virus. A poisonous gas will be released. A common steel or machine steel rod is all you need. I use very small O-rings placed several inches apart to prevent the rod from touching the lands of the barrel and shorting out.The solution will clean the grooves with no issues where the o-rings are.
I rubber cork the breech end to prevent leakage with the rod centered and 1/2 way into the cork.
The muzzle end is O-ringed and a plastic funnel is heated up and slipped over the end of the barrel. This provides a water tight seal. If it does dribble, hot melt glue will seal it up and does no harm to the bluing.
The funnel body acts as a reservoir for holding the electrolyte solution. As it cleans you will clearly see the scum form on the top of the funnel. The funnel also prevents the crud from over flowing and making a mess.
The start of the process is easy to see as you can look into the funnel and see the gas bubbles almost instantly form and rise to the top. This shows you it is hooked up properly and is working. If you do not see bubbles within 10 seconds, stop. You have a short or the solution with the Washing Soda is too weak to conduct current.
After a few hours you can add new solution and check the bore rod. The rod should be cruddy black covered from iron oxide that has been plated to it. The barrel and solution will be warmer than room temp. It will never get hot.
You can add a safe cleaner to the solution to aid in removing non metallic deposits from the bore. Dawn and Simple Green work well.
You want to make sure other cleaners are bluing safe.
A small amount of hydrogen will be given off. Just use it in a room with normal ventilation,nothing special with fans is needed.
You can scale up the process for rusty gun parts by using a plastic bucket, cat litter container or large plastic dog food container.
The cleaning you get has to be seen to be believed.
Tap water is fine. Distilled water is not needed at all.
The instructions for after cleaning posted above should be followed.

[pcmacd]

Used to use this a lot with farm fresh tools. Negative (black) lead from battery charger goes to the item for de-rusting, red goes to the sacrificial anode (I always used a stainless steel pan lid).

Sent from my LG-H918 using Tapatalk

Stainless steel has chromium in it, which makes your resulting solution seriously dangerous. Good old rebar would be much safer.

[swheeler]

Let us know how the barrel looks and shoots after your done.

[pcmacd]

I do believe this is backwards. Red+ to the barrel, Black - to the rod is how should be hooked up.https://video.search.yahoo.com/yhs/search?fr=yhs-pty-pty_news&hsimp=yhs-pty_news&hspart=pty&p=building+a+electric+gun+barrel+cleaner#id=2&vid=28e41b2322d110a04222de5af1400e32&action=viewhttps://video.search.yahoo.com/yhs/search?fr=yhs-pty-pty_news&hsimp=yhs-pty_news&hspart=pty&p=building+a+electric+gun+barrel+clea

I built this one decades ago, used it on many many milsurps and it does a fine job, hooks up and runs just like Foul Out III barrel is always the anode +, but I'm removing lead and copper, maybe some rust too.
https://i.imgur.com/KNZGH2I.jpg

If I understand your position, I respectfully disagree with your notion that the positive connection is to the barrel for removing rust.

Metal ions (i.e. RUST) follow the current flow, from negative to positive.

--->>> That's just basic physics, sir. <<<---


https://en.wikipedia.org/wiki/Rust

See section entitled "Treatment."



If you have had success with the configuration you outline (assuming I understood it? It was a little confusing) I am sitting here scratching me 'head wondering how.

Everybody gets an opinion. We are not always right, including me.

[fiberoptik]

http://www.frfrogspad.com/homemade.htm
Bottom of page. Froggy’s info. How to make the device, solutions, even Ed’s Red +.
Good info.

Sent from my iPhone using Tapatalk

[swheeler]

If I understand your position, I respectfully disagree with your notion that the positive connection is to the barrel for removing rust.

Metal ions (i.e. RUST) follow the current flow, from negative to positive.

--->>> That's just basic physics, sir. <<<---


https://en.wikipedia.org/wiki/Rust

See section entitled "Treatment."



If you have had success with the configuration you outline (assuming I understood it? It was a little confusing) I am sitting here scratching me 'head wondering how.

Everybody gets an opinion. We are not always right, including me.

Yes I have had much success using it the way described to remove copper and lead, cupro nickle too I believe. I did post two youtube links also. I'm not a big wiki fan;-)

Like the picture shows RED to BARREL- BLACK TO ROD. You know sacrifice a little copper or lead to the cathode ROD

[swheeler]

TRY THIS ONE............https://video.search.yahoo.com/yhs/search?fr=yhs-pty-pty_news&hsimp=yhs-pty_news&hspart=pty&p=building+a+electric+gun+barrel+cleaner&

[pcmacd]

Yes I have had much success using it the way described to remove copper and lead, cupro nickle too I believe. I did post two youtube links also. I'm not a big wiki fan;-)

Like the picture shows RED to BARREL- BLACK TO ROD. You know sacrifice a little copper or lead to the cathode ROD

Indeed, SWHEELER, you are correct here about polarity. Apparently I just boiled off rust with the agitation of the hydrogen/oxygen bubbles.

Wrap your brain around this (wikipedia, "current" was the subject I hope?) : 263443

I posed the polarity and electrolyte question in a forum haunted by chemists, and here's what I got back:

<begin quote>

What you are attempting to do is to ELECTROPOLISH the metal. In an electropolishing setup, the work piece is always the ANODE (+) while the cathode can be any number of different conductors. There are as many varied combinations of anode & electrolyte as there are metals to electropolish and so what you are attempting to do can get very complicated. However, I will point out that, as the kids say nowadays, "you're doing it wrong..." - steel electropolishing should always be done at low pH and typically using a concentrated acid mixture of phosphoric and sulfuric acid. Doing it a high pH is going to evolve a lot of hydrogen at the work piece which will not only fail to properly reduce the metal surface but also likely cause hydrogen embrittlement. Hopefully this rifle barrel will never actually be used....

The first step in any electropolishing process is to physically CLEAN the metal surface of any rust, smut or dirt. This usually requires a stiff brush, a cleaning solution (typically containing a surfactant) and, if necessary, a very light polishing clothe. Then the steel surface should be PICKLED in concentrated hydrochloric acid to reduce any oxides. The pickling process can take several minutes to several hours depending on how heavy the build up is. Finally the part should be rinsed (multiple times) and dried. Once the surface is prepped, you then attach the work piece to the positive (+) anode and your cathodes (-) to the negative terminal.

Depending on the geometry of the part, it is often good practice to have multiple cathodes surrounding the workpiece. This will cut down on current density variations. Electropolishing is typically done at a constant voltage to avoid overcurrents and "burning" the part. You want to apply enough voltage to remove any remaining oxides and begin polishing (dissolving) the metal but not so much voltage that you electrolyze the water in solution thus forming hydrogen gas. If you are getting lots of hydrogen evolution at the work piece, your voltage is set too high and that will tend to cause surface roughness variation well above tolerance.

Concentrated sulfuric and phosphoric acid mixtures are used because they are very viscous and high conductivity solutions that help to remove metal at a decent rate without evolving too much hydrogen gas. If the part is stainless steel, the current will eventually reduce in magnitude as the chromium reforms the passivation layer. Low grade steels will tend to over etch and so you must visually inspect the workpiece. After the piece is sufficiently polished, you want to immediately remove the part and rinse it thoroughly in flowing deionized water baths. Finally, if passivation is required, one typically finishes the part in a concentrated nitric acid soak to help fully form the oxide passivation layer (and, of course, rinse and dry the part when you are done).

If the work piece is attached to the cathode, you will get plating of metal onto the surface. But what likely is happening is not polishing or plating but oxygen evolution essentially blowing off all the junk on the surface. By doing it in reverse, you risk plating out contaminants onto the surface which will make the mar the work. Electropolishing is a very complicated process and so you should investigate it a little more so you don't damage anything you value. There are metal workshops out there that will electropolish to order but you usually have to give them a large enough order or wait a long time until they can add your part to a batch process.

Look up "metal finishing services" and you might be surprised what you find...these guys are local to me and they do some pretty cool custom work (including rifle barrels....) -

>end quote<

Note that "low pH" means an acidic environment. Why in the world is Borax a favorite, as it is the opposite, a "base" or "caustic???"

I have SERIOUS reservations regarding CONCENTRATED SULFURIC, HYDROCHLORIC, OR PHOSPHORIC acids inside a barrel to "pickle" it? They do that with 20 ton steel ingots before they heat them red hot and roll them. I don't think this applies to the insides of a gun barrel... but who knows???

In intend to try this again with the correct polarity using a mild phosphoric acid as the electrolyte. Coke is good for that, as is the CLR product for removing mineral and rust stains from sinks and such. CLR might be a better bet, as Coke is so dark it might be difficult to find what one is bringing off the barrel (I learned in the sixties that Coke was awesome for removing rust from bumpers. Nobody could say why, but it has scads of phosphoric acid in it. Good for teeth? Well, what do YOU THINK????)

In fact, I have read multiple posts on using CLR for a carbon and rust removal solution in rifle barrels in conventional cleaning scenarios

mac

The guy wrote the above was domiciled in Tucson. http://www.cmf-capitalmetalfinishing.com/polishing-photos

Thanks again to y'all.

[swheeler]

pcmacd; I have used a brass cleaner made by Birchwood Casey that is a solution of phosphoric acid and soap, might be perfect for your use inside a barrel? I also have some "aluminum boat cleaner" it is in the shed so I don't have the name right now, but it is Formic acid and may also work for you, I'm careful not to get it on my skin when using it but removes tarnish instantly, just spray on/ hose off. Scot

[Rapidrob]

Most caustic acids will remove gun blue.
Phosphoric Acid and Citric Acid will remove most deposits and not damage the bore of the firearm.

[swheeler]

Indeed, SWHEELER, you are correct here about polarity. Apparently I just boiled off rust with the agitation of the hydrogen/oxygen bubbles.

Wrap your brain around this (wikipedia, "current" was the subject I hope?) : 263443

I posed the polarity and electrolyte question in a forum haunted by chemists, and here's what I got back:

<begin quote>

What you are attempting to do is to ELECTROPOLISH the metal. In an electropolishing setup, the work piece is always the ANODE (+) while the cathode can be any number of different conductors. There are as many varied combinations of anode & electrolyte as there are metals to electropolish and so what you are attempting to do can get very complicated. However, I will point out that, as the kids say nowadays, "you're doing it wrong..." - steel electropolishing should always be done at low pH and typically using a concentrated acid mixture of phosphoric and sulfuric acid. Doing it a high pH is going to evolve a lot of hydrogen at the work piece which will not only fail to properly reduce the metal surface but also likely cause hydrogen embrittlement. Hopefully this rifle barrel will never actually be used....

The first step in any electropolishing process is to physically CLEAN the metal surface of any rust, smut or dirt. This usually requires a stiff brush, a cleaning solution (typically containing a surfactant) and, if necessary, a very light polishing clothe. Then the steel surface should be PICKLED in concentrated hydrochloric acid to reduce any oxides. The pickling process can take several minutes to several hours depending on how heavy the build up is. Finally the part should be rinsed (multiple times) and dried. Once the surface is prepped, you then attach the work piece to the positive (+) anode and your cathodes (-) to the negative terminal.

Depending on the geometry of the part, it is often good practice to have multiple cathodes surrounding the workpiece. This will cut down on current density variations. Electropolishing is typically done at a constant voltage to avoid overcurrents and "burning" the part. You want to apply enough voltage to remove any remaining oxides and begin polishing (dissolving) the metal but not so much voltage that you electrolyze the water in solution thus forming hydrogen gas. If you are getting lots of hydrogen evolution at the work piece, your voltage is set too high and that will tend to cause surface roughness variation well above tolerance.

Concentrated sulfuric and phosphoric acid mixtures are used because they are very viscous and high conductivity solutions that help to remove metal at a decent rate without evolving too much hydrogen gas. If the part is stainless steel, the current will eventually reduce in magnitude as the chromium reforms the passivation layer. Low grade steels will tend to over etch and so you must visually inspect the workpiece. After the piece is sufficiently polished, you want to immediately remove the part and rinse it thoroughly in flowing deionized water baths. Finally, if passivation is required, one typically finishes the part in a concentrated nitric acid soak to help fully form the oxide passivation layer (and, of course, rinse and dry the part when you are done).

If the work piece is attached to the cathode, you will get plating of metal onto the surface. But what likely is happening is not polishing or plating but oxygen evolution essentially blowing off all the junk on the surface. By doing it in reverse, you risk plating out contaminants onto the surface which will make the mar the work. Electropolishing is a very complicated process and so you should investigate it a little more so you don't damage anything you value. There are metal workshops out there that will electropolish to order but you usually have to give them a large enough order or wait a long time until they can add your part to a batch process.

Look up "metal finishing services" and you might be surprised what you find...these guys are local to me and they do some pretty cool custom work (including rifle barrels....) -

>end quote<

Note that "low pH" means an acidic environment. Why in the world is Borax a favorite, as it is the opposite, a "base" or "caustic???"

I have SERIOUS reservations regarding CONCENTRATED SULFURIC, HYDROCHLORIC, OR PHOSPHORIC acids inside a barrel to "pickle" it? They do that with 20 ton steel ingots before they heat them red hot and roll them. I don't think this applies to the insides of a gun barrel... but who knows???

In intend to try this again with the correct polarity using a mild phosphoric acid as the electrolyte. Coke is good for that, as is the CLR product for removing mineral and rust stains from sinks and such. CLR might be a better bet, as Coke is so dark it might be difficult to find what one is bringing off the barrel (I learned in the sixties that Coke was awesome for removing rust from bumpers. Nobody could say why, but it has scads of phosphoric acid in it. Good for teeth? Well, what do YOU THINK????)

In fact, I have read multiple posts on using CLR for a carbon and rust removal solution in rifle barrels in conventional cleaning scenarios

mac

The guy wrote the above was domiciled in Tucson. http://www.cmf-capitalmetalfinishing.com/polishing-photos

Thanks again to y'all.

Pcmacd: I certainly hope you did not "hydrogen embrittle" the barrel but do fear the worst. I use 2 1.5 V batteries in series and my solution is 1 part vinegar, 1 part ammonia and 2 parts distilled water. On some really fouled up mil surps I have ran 2 full 45 minute cycles, changing solution at end of the first cycle and restarting, I have never felt the barrel get warm let alone hot. If I shot it I think I would strap it to a tire with a bungee and hide behind my car just incase! Good luck