New take on "slow" rust bluing

[andremajic]

Ok, so most people have heard about or used rust bluing before right?
Basically, you swab the object with an acid mix bought from midwayusa or brownells, put the part in a sweat box, boil it to deactivate the acid, card off the rust, and repeat the process up to 8 times to get full coverage. 8 days to finish optimally.

Most smiths don't do this any more because it's just too time consuming and most people are cheap and don't want to pay for the labor involved. Also, if you apply the finish unevenly, you will get streaking that takes even more applications to blend in.



Here's something I've been experimenting with that I'd like to share with the community at large:

If you haven't seen electrolytic rust removal before, just type it into youtube and watch a video. Pretty simple. A battery charger, a sacrificial anode, some baking soda and some water. All these aim to get rid of rust, leaving it all on the sacrificial anode.

What we want to do is create rust! (black oxide)

All you do is reverse the current. Put the positive lead on your part that needs bluing, put the negative lead on something that is rusty.

After a couple hours, turn off the electricity and remove your part. It should have a nice surface layer of rust on it. Underneath that surface is black oxide.

Using a carding wheel (recommended) or some 0000 steel wool, start lightly polishing the red rust off. Keep putting it back in the tank, rusting, and carding until the entire surface is covered in black oxide. Because we are using baking soda, just rinse it off in the sink. You don't have to boil the part to remove any acids, like with the bluing solutions out there.

The electrolysis only works in a straight line between the anode and cathode, so you will need to rotate your part as it gets covered. As soon as you get adequate coverage, and you're happy with the finish, put the part in a solution of ATF/WD-40 to displace the water and halt any future rusting.

WARNING: Try this on some tools in your garage before anything gun related. If a part is extremely thin, like a knife blade you will eventually rust the sharp edge off of it and it will need resharpening. Rusting still causes a part to lose some of it's mass, so I would highly recommend only using this on larger parts. In a nutshell, don't use it on small internal gun parts.

http://castboolits.gunloads.com/imagehosting/44874ef87d6cc4ed5.jpg

2nd WARNING: See those little bubbles rising to the surface of your water? That's hydrogen! The byproduct of putting an electrical current thru water to convert/remove rust creates hydrogen. Don't smoke or do this around open flames or sparks. If you do this indoors, open a window or turn a fan on to disperse the gas that rises from your container, or if you're like me, open your garage door.

Because this doesn't involve the use of acids, expensive solutions, or long wait times, I believe that you can get pretty proficient in this technique in a short time. It's so simple, I'm sure some gunsmiths have figured it out on their own, but don't want to give their competitors an edge. I KNOW I'm not the only person to figure this out.

It took me about 8 hours to complete covering a large high carbon knife blade in black oxide (Instead of 8 days.) There was a little pitting on the back of the blade that I didn't like, so I ground off the pitting and it's back in the solution as I type this. (I think the pitting was because I never bothered to card that part off the knife off, so it accelerated the rusting.)

http://castboolits.gunloads.com/imagehosting/44874ef87d6d39081.jpg

The finish looks like what you see on drill bits. It's a non glare, dark grey finish (almost black) that doesn't reflect light and holds oil just like parkerizing. I believe that the higher the carbon content, the faster you'll see results. If there is high nickel or chromium content, your part might not rust like you want it to, and it might be a better cantidate for hot salt bluing or using a harsher solution than baking soda.

I believe that information like this is too good to keep a secret, and there are countless guns that won't ever get refinished because it's too expensive to do for most folks, so my motivation is to help out everyone by sharing this. That's how society improves. The free exchange of information.

Now go have fun experimenting and save your rusty tools!

Andy.

[andremajic]

Ok, update:

If you're just mixing it up, put approx 1/3 cup baking soda per gallon of water. A squirt of dishwashing detergent will help cut through any crud that acts as a barrier to the electrolysis.

UPDATE: DON'T USE SALT, stick to baking soda!

I tried salt and there was uneven pitting that I had to take off with the belt sander.

Will post pics of process and finished/oiled blade when done tonight.

Andy.

[andremajic]

If you're wondering what that groove running the length of the blade is, it's the race that the bearings used to ride in. I wasn't able to fully flatten out this because the metal is so danged hard. 52100 bearing steel is a premium knife steel, loved by custom knife makers for it's qualities.

I like the way the forging marks show on the handle and plan on keeping it rough and rustic looking, so I will be leaving it that way. (I made the knife for me anyways!)

After pulling it out of the WD-40 and wiping it down well with newspaper, I applied some clove oil to the blade and handle, so that it's got more of a "food safe" oil.

I jokingly refer to this as "The Zombie Killing Knife" whenever someone asks what it would be used for. The finger grooves are cut so that it fits my hand perfectly and the weight is perfectly balanced.

http://castboolits.gunloads.com/imagehosting/44874ef87d81a19c3.jpg

Once the edge has been sharpened so it can shave hair, there will be a nice contrasting white metal edge to compliment the black oxide finish.

http://castboolits.gunloads.com/imagehosting/44874ef88d09c6385.jpg

The closest thing I've seen to this finish on a gun would be a remington 700 factory barrel from a synthetic model. The beauty of this system is, that since the electrolysis works on line-of-sight from cathode to anode, that the inside of a gun barrel will not be coated.

If you are working on a gun barrel, I would get some of those silicone plugs from mcmaster carr to keep the water out.

Andy.

[Cap'n Morgan]

Interesting! I'll give it a try. Must you use a rusty offer anode, or could you just add some rust scrapings to the water?

[imashooter2]

When I use electrolytic rust removal, the anode gets eaten away. This process turns the good part into the anode... Why doesn't the good part get eaten away?

[williamwaco]

How do I protect the bore?



.

[andremajic]

Interesting! I'll give it a try. Must you use a rusty offer anode, or could you just add some rust scrapings to the water?

I had plenty of steel dust that I swept off the floor and added to the solution, just to give it some extra iron, but the first run I didn't add anything extra. Not sure if it helps or not.

I had a rusty gun barrel that was the rust donor for this project. There were 2 projects done at once!

Andy.

[andremajic]

When I use electrolytic rust removal, the anode gets eaten away. This process turns the good part into the anode... Why doesn't the good part get eaten away?

Well, I believe that "some" of the good part gets eaten away. The very sharp part of my knife blade was dull, so the edge was rounded. It resharpened in a couple minutes though.

Remember, you're leaving it in to coat it with a "light" layer of rust, removing the red rust, leaving black oxide behind and repeating until the entire part is covered with black oxide.

I'd say you lose a lot less metal this way than if you were doing parkerizing, boiling a part in acidic water for 15-20 minutes.

Just start experimenting and post your results on this board. Start with non gun stuff first though!

[calaloo]

In real rust blueing the rusted part is boiled in distilled, or at least mineral free, water and the red rust becomes black. the loose black oxide is carded off and the process is repeated untill the desired depth of color is reached.

[andremajic]

In real rust blueing the rusted part is boiled in distilled, or at least mineral free, water and the red rust becomes black. the loose black oxide is carded off and the process is repeated untill the desired depth of color is reached.

So it would be better to boil the parts between the bouts of electroysis? I'm just experimenting right now, and haven't taken the time to boil my parts. I'll try it and post the results.

I always figured that the main reason for boiling was to get rid of the acid.

Andy.

[MBTcustom]

This is exactly what my electro etcher does. It has two settings, one etches a deep mark and the other produces a black mark. I believe the only difference between the two is the current direction. I am building a large electroetcher that will allow me to burn designs into the metal but I was also going to experiment with the same thing you are doing. Very interesting! Subscription has been added.

[Cap'n Morgan]

I always figured that the main reason for boiling was to get rid of the acid.

If you do a rust bluing (or browning actually) and skips the boiling, the surface will take on a nice brown color like seen on old damascus barreled guns.

[eniku40]

Hmm... Worth a try with my rusty(ish) reloading press handle.

[BeeMan]

Protecting the bore? Don't know if it will work, but someplace mentioned coating the bore with lacquer. After done, rinse bore with lacquer thinner to remove. Gonna give it a try when I get a round tuit. Couple home made push through sizers here, one of which needs lapping to final size. Blue first and if the bore gets etched, lapping should put the shine back.

BeeMan

[MBTcustom]

What ever happened to this project? I was hoping for more pictures and tests.
Did you run out of steam?

[andremajic]

http://castboolits.gunloads.com/imagehosting/44874f80f94164361.jpg

Sorry if it's a crappy pic. I've been using the knife to chop firewood recently, so there are scratches on the polished part of the blade.

Very sharp, and it doesn't lose the edge!

Andy.

[edwin41]

ive read this post and must add a warning.
when you clean hard metal with this electrolyse method , it can leave the metal
briddle , in dutch this is called "koolstof brosheid ".

carbon embrittlement is what google gives me as a translate.
be very carefull with this methode , especially barrels !

[waksupi]

ive read this post and must add a warning.
when you clean hard metal with this electrolyse method , it can leave the metal
briddle , in dutch this is called "koolstof brosheid ".

carbon embrittlement is what google gives me as a translate.
be very carefull with this methode , especially barrels !

Very interesting. I had never heard that being a problem with electrolysis. I found this link;

http://www.vacaero.com/Industrial-Heating-Magazine-Articles/News-Info-From-Industrial-Heating-Magazine/the-embrittlement-phenomena-in-hardened-a-tempered-steel.html

It has no mention of molecular alignment with electrolysis, it just covers the known brittleness due to various heat treatments.
Do you have a link directly pertaining to the electric process weakening metals? I do find reference to hydrogen embrittlement, but only under high heat.

[jblee10]

Very interesting stuff! Your knife appears "black" in the photo like a caustic blue job. The thing I like about cold rust blueing is the rich "gun metal gray" color. Is the knife more gray then it appears in the picture?

[JeffinNZ]

Many years ago a friend made me a new screw in aperture for a tang sight. I wanted to blue it and read somewhere that heating it red hot and dropping into beeswax would work. IT DID! Still beautiful to this day.

[Goatwhiskers]

I had an old K31 Swiss that had been kept under the bed brought in once, it was coated with a super fine rust. Used the conventional electrolytic rust removal method, removing about every 5 minutes or so and scrubbing with 4/0 steel wool. When I finished the blueing was the most dark blue, good as any rust blue you ever saw. This thread makes me want to go back and experiment further. Goat

[andremajic]

Very interesting stuff! Your knife appears "black" in the photo like a caustic blue job. The thing I like about cold rust blueing is the rich "gun metal gray" color. Is the knife more gray then it appears in the picture?

I know that depending on your color/brightness settings on the monitor it might appear different shades/darkesses, but I can assure you that it's a charcoal grey, almost black color. A lot like parkerizing on factory barrels.

I just bought an actual carding wheel used for bluing, so I'm going to repeat the process, boiling between rusting processes and see how the next one turns out!
(I didn't boil between rusting when I did this blade.)

This should be cool!

Andy.

[MBTcustom]

Keep it up buddy! I've been watching this thread for months to see your progress.

[andremajic]

http://castboolits.gunloads.com/imagehosting/44874fecdb9b641c3.jpg

I decided to take the dive and try it on one of my shorty 300 blk barrels, while I waited on delivery of my pistol lowers.

[andremajic]

Ack. I got paranoid when I noticed that the rust wasn't showing up evenly, so I decided to scrub all the rust off, drying it with a heat gun and cerrakoted it.

I was also paranoid about the threads losing material from them. I did notice that the carding wheel did a great job and you could see a kind of rainbow of color to the metal where the rust was carded off.

Next barrel I'm going to try this on will be something like a 1911 barrel. It should fit in a saucepan easily for the boiling part too.

I'll post pics when I start it up.

[3006guns]

I need to inject a comment here. I've been using this method to remove rust on my antique engine parts for several years now. The mantra to remember is to place the negative electrode on the rusty part (negative=take away rust) and the positive on your sacrifice anode. The process transfers the oxide (rust) to the sacrifice anode. This is the setup for removing rust, the opposite of what's being described above.

Note that word....SACRIFICE. If the polarity is reversed your precious part will end up pitted as the metal is transferred to the other anode. My whole point is to be very careful when using this for bluing. I'm sure it works quite well and really speeds up the rust bluing process, but walking off to have a beer or just not paying attention can really do some damage. A low amperage battery charger (trickle charger)might be the safest route....and stick around to keep an eye on it.

Might also be a good idea to try it on several "experimental" bits and get some experience before applying it to your best Smith and Wesson!

Edit: Because the process is "line of sight", just place several rusty anodes in the tank surrounding your part. That way you don't have to keep turning it for an even coat.

[andremajic]

I need to inject a comment here. I've been using this method to remove rust on my antique engine parts for several years now. The mantra to remember is to place the negative electrode on the rusty part (negative=take away rust) and the positive on your sacrifice anode. The process transfers the oxide (rust) to the sacrifice anode. This is the setup for removing rust, the opposite of what's being described above.

Note that word....SACRIFICE. If the polarity is reversed your precious part will end up pitted as the metal is transferred to the other anode. My whole point is to be very careful when using this for bluing. I'm sure it works quite well and really speeds up the rust bluing process, but walking off to have a beer or just not paying attention can really do some damage. A low amperage battery charger (trickle charger)might be the safest route....and stick around to keep an eye on it.

Might also be a good idea to try it on several "experimental" bits and get some experience before applying it to your best Smith and Wesson!

Edit: Because the process is "line of sight", just place several rusty anodes in the tank surrounding your part. That way you don't have to keep turning it for an even coat.

Yep, I'm thinking the best way would be to find some rusty water pipe and put some insulating "donuts" around the barrel to keep it from shorting out. PVC would be a good holding container as it's cylindrical and non conductive.

I'm not giving up, just putting it on hold for a sec.

[nanuk]

Andre: your rusty water pipe if sized correctly could BE your holding container, No? Just put the electrode directly on it.

use a wooden down or fiberglass fencing rod through the bore and tape to bring it up to size for a snug fit, and donut around the rod so you get bluing on ALL surfaces at once.

[andremajic]

Andre: your rusty water pipe if sized correctly could BE your holding container, No? Just put the electrode directly on it.

use a wooden down or fiberglass fencing rod through the bore and tape to bring it up to size for a snug fit, and donut around the rod so you get bluing on ALL surfaces at once.

Yeah it would work. As long as the pipe is vertical and sticks up above the water solution so that you can clip the charger clamps to the pipe.

It would have to be a large pipe however, otherwise the alligator clip wouldn't have space to clamp on the barrel and would risk shorting it out.

[plourbag]

One of the members at our local gun club (NSW, Oz) uses a mixture of molasses and water (not quite sure of the ratio) not only as a rust remover but as an agent that supplies a finish like parkerising. Only one trouble - it takes about six months. Looks good though, his lee enfields are sight to behold. Just needs patience, he has it - I don't.

[Just Duke]

Suscribed

[oldred]

Ok I have been reading this and the OP has obviously got a very interesting idea but FWIW I would like to address a couple of things, first "washing soda"- Sodium carbonate (also known as soda ash, Na2CO3) is what is normally used in electrolytic rust removal not "Baking Soda" or Sodium bicarbonate (NaHCO3) as was described here. I have used electrolytic rust removal for many years and while Baking Soda can be used in a pinch it does not work nearly as well as Washing Soda (Sodium Carbonate) so would the Wash Soda work better here? -or not. Also a couple of things in the original post about rust bluing is a bit misleading such as the statement "boil to deactivate the rust", this wrong because that is not at all the purpose for boiling and the rust (or more correctly any remaining acid solution) needs to be deactivated by washing with a Soda/water rinse after finishing the series of rusting/boiling/carding steps and before oiling. Actually the boiling is done as a step to convert the iron oxide (or Ferric Oxide- rust which is red), to the Ferric Ferrous Oxide state (Fe3O4), which is blue-black but this does not deactivate the solution used to induce the process. The electrolytic process simply forms the magnetite/Ferric Ferrous Oxide onto the metal surface without first going through the oxidation/conversion process so it does work. However after reading this it would seem that the only major advantage would be that it can be done in about 8 hours instead of 8 days but fellows it does not take 8 days to do rust bluing if the right solutions are used. "Express" blues such as Mark Lee Express blue or the well known Blegian Blue formula will produce a beautiful blue that is every bit as durable as the slow blues, it should because the resulting finish is the same. Express rust bluing can be done in a lot less than 8 hours and instead of electrolytic equipment all that is needed is a tank to boil the part in and the solution itself, the part is simply warmed with a heat gun or small propane torch (WARM not blistering hot!) and the solution applied followed by immediately boiling and carding- then simply repeat 5 to 8 times or so or until the desired color is achieved. Not trying to dissuade anyone from the electrolytic process or in any way am I trying to highjack the OP's thread but I thought that the Express rust blue should at least be mentioned because it is much faster to use than either the slow rust or electrolytic processes, and much simpler than the electrolytic process. Some folks prefer the slow over the express rust blues since the slow blue is the traditional way of doing and some are of the opinion that it is easier to get an even blue while users of the express type solutions seem to prefer the shorter times and don't seem to have any problem with uneven bluing, that has been the case for me and the express blues have done a fantastic job in a short time with minimal equipment setup and work.

[Norbrat]

I would love to be able to get hold of an express blue solution, but suppliers will not post to Australia. About the only thing you can get here easily is cold blue pastes, which I have tried and are next to useless for a complete re-blue job.

I do have a formula for express blue solution in an old NRA gunsmithing book, but it doesn't seem worth buying half a pound each of 4 different chemicals, assuming I can even find them, for a total of 6 ounces or so of salts to be dissolved.

I know there is another thread in the gunsmithing section about making a hot blue solution from caustic soda drain cleaner, but I don't think that is a good process for me to try.

As I have a couple of firearms to re-blue, I think I have no choice but to try the slow rust bluing process.

[oldred]

Norbrat, I don't know if you have ever done slow bluing before but I don't think you will be disappointed with the results. It is quite easy to do as long as some simple rules are followed such as keeping the parts spotlessly clean (watch those grimy paws!) and keeping a close watch on the rust process so it does not get heavy enough to pit. It is a very simple and easy to do means of achieving a beautiful finish that would compliment most any firearm, a plus is that it is also probably the most durable of the blue type finishes.

[Norbrat]

I haven't tried slow rust bluing yet.

I like the idea of the express blue as I should be able to complete the job in one afternoon/evening.

Finding the time to re-heat the tank, boil and card every evening after work for a week or so is a bit more difficult. But at least the nitric/hydrochloric acid/nails formula for the bluing solution is posible to make without too much trouble.