BLACK STEEL in 10 minutes: CAUSTIC BLUING Tutorial (with Household Materials)
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- Опубликовано: 5 сен 2024
- As promised, here's part 2 of 3 of my steel bluing guide.
This one covers caustic bluing, a process that allows getting a finished bluing in a matter of minutes, making steel parts as black as they can be. As usual I'm only using readily available chemicals.
Differently than rust bluing, this process is dangerous because of the large abounts of caustic soda required. Do not attempt without proper personal protective equipment (PPE).
A special thanks goes to Michelangelo Neri Orliani for helping in the making of this project
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Important tip!! Don't do this in a workshop you care about - it releases caustic vapors and you will find anything made of steel or cast iron forming a red surface rust almost immediately. I do this outside now for that very reason, the first time I performed hot caustic bluing in my shop I found my lathe, drill press, and other tooling had a red rust on the bare metal surfaces the next day. It cleaned off fine but lesson learned. Also be careful on the acid step, if you want a bright polished finish you need to start with bright polished steel, but too long in the acid or too strong acid will take the polish back to a matte finish and the blued steel will be matte also.
Yes indeed.
It is an exceptionally dangerous process as caustic DOES NOT stop corroding the skin and flesh like acid.
One drop on unprotected skin will eat through and make it bleed.
I was a gunsmith.
You're overreacting. We had a 10,000 gallon caustic tank at 970+F (melting pure caustic) and it was an open air tank. It's at most going to eat paint. As long as you have decent airflow though and not condensating the tankvapors you'll be fine.
The first time I tried this, the parts came out perfect. Beautiful black and shiny. It was a knife made from leaf spring steel and other parts made from mild steel. My next attempt, same metal, same solution, same methods…one knife came out a gorgeous coppery color, two came out black. I have no idea what I did different. One poster here says you can get chemical skin burns just from the air. That’s a real thing…I could feel my exposed skin mildly stinging, and I had the garage door open.
@@6Sally5 The red coppery colour is most likely red iron oxide which means the temperature of the bath went too high. I have resolved this by taking the reddish parts and washing them of caustic salts and then boiling in a pot of distilled water. This converts the red iron oxide to black iron oxide. Once it turns black again you can return it to your bluing salts and it will take an even darker blue.
Heed the safety warning !!!
I have still the scars back from when I was a lad, and thought I was invincible .
I still use hot caustic but with full arm gauntlets, full length rubber apron and full face mask.... once burned, twice shy :
you deserve so many more subscribers.
This is a newer, secondary channel, but yes, you are correct.
@@addmix correct on both counts :D
That copper-colored bluing is really beautiful.
Always wear eye protection and use gloves, a guy i worked with at a metal finishing firm got lazy while caustic blueing and did not wear his issued safety eye wear and managed to catch a tiny little drop of super hot sodium hydroxide solution when he added room temp parts into it creating a spattering of the solution, his eye was destroyed in seconds,
Hey there's the plum/red I asked about on a previous video! A very interesting video. Thanks for making them! I don't know why but metal finishes are all just super fascinating.
That color will also develop in commercial bluing salts if the temperature goes too high. Brownells Oxynate No. 7 is intended to work at about 395°F/201°C. At around 410°F/210°C it will turn some alloys purple.
You packed a lot of info into this short vid. Very concise & much appreciated.
Top notch content as usual, love your work, keep it up!
I realise that this gives them more permanent finish but is an extremely dangerous operation for the less competent amateur. I was suggest cold chemical bluing for these people would be a better option and a safer one.
I don't have the space to do a setup like this but fascinating stuff! I'll stick to the more traditional rust and boil method 👍
Thank you for this information I have made my own rust blue solution for years using acids and iron, and water but a working hot bath solution has eluded me until now
thank you Carlo for your continuous work with providing us excellent information and entertainment!
I've done this as a gunsmith for some 15+ years with a larger commercial set up. One needs to appreciate what a colossile pain in the @ss it is to get just perfect out come every time. Some will look better than factory, some look as if it is a total disaster, mostly due to unknown alloys of steel.
Thank you very much. I didn't know about the lime. I live near the sea, and rust is a constant struggle.
very good videos, thanks for sharing your knowledge
Top content! A real enrichment! Am very glad that finally someone passes on detailed guidance Restauratrion. I personally like to restore my finds. Since such instructions are very much worth. I appreciate that! Please keep up the good work 👍
I had to choose between this and a recipe to cook beef bourguignon.
I chose wisely.
I would like you to make a video on how to nickel them
These videos are great 👍
Orange blueing looks soo nice tho.
Thanks! Surley not going to do it at home, but it’s cool to know how to do it :)
I truly appreciate your information and your style of instruction. Please know it's it enjoyed.
I'm very glad it is!
Very cool!
I will keep this one for the archive.
Greetings,
Jeff
Excellent tutorial. Excellent speaking skills. Than you
This is amazing but I have to say, I’m definitely never going to do this. Cool to know though!
Absolutely top flight content as usual. Thanks you!
I used to 'Hot Salts Blue' and one day a gunsmith friend wandered into the backyard where I was blueing a couple of rifles.
He had no shoes on and stood unadvisedly close.
The product I used worked at 150 degrees celsius.
A tiny droplet of the solution landed on his bare foot and instantly burnt/corroded it's way through the skin.
A droplet of blood was seen after he had finished hopping around and swearing.
It's dangerous stuff.
Thanks for the great info. One question though. Are the boiling vats you're using purpose made for this, or are they commonly available for other uses? They look familiar but I just can't quite place where I've seen them before.
They are normally purpose built, either bought from a gunsmithing supplier or made on purpose from sheet steel. I'm not aware of any other use, with the possible exception of pankake molds or some designer flower pots... but make sure they're water tight and steel only first!
look like bread loaf tins to me
Wonderful Video , well scripted and shot. 10/10
Ideal for doing in one's kitchen. The couch looks comfy anyway.
Amazing.. I enjoy the content. Hope all is well on your side of the world.. getting materials soon..
another interesting and educational video ,thanks 👍
Hello, can you please talk in one of your next videos about cold blueing solutions that you can buy on marketplaces and apply by brushing it on surfaces? How it compares to the chemical methods you describe here? Thank you.
Interesting info about the reddish colors. I have seen Makarov pistols with deep crimson/cherry colored hammers and safety levers. Made me wonder what could have caused it. Now I know that steel composition is to blame.
They could be heat blued which causes a strawed color at first then turns blue. Some beretta pistols were made like that for small parts
Rust bluing looks more beautifull when you consider the risks involved in caustic bluing.
Still waiting for the heat bluing video. I wonder if you know some special tricks for complicated shapes. Looking forward to it :)
I'll start working on it soon. Getting uniform temper colors is relatively easy (straw, purple and blue), getting the so called blue-black is much more complicated.
What does one do for large parts (like 6ft long saws?) - thanks for an excellent channel. New sub.
insanely informative! Haha I probably won’t try this at home though! My workshop is a lot more controlled and safer environment so that’s probably better.
How do I dispose of the liquids? I figured I wouldn’t just dump it down my drain, given it may damage the pipes..
Take my words with a pinch of salt, since I'm not an environment expert, but Sodium Hydroxide is widely used as a drain opener. Actually most drain cleaners nowadays are mostly sodium hydroxide, so if you can use drain cleaner in your house, you should also be able to dispose of the caustic bluing solution in the drain, once it cooled down to room temperature. Potassium nitrate is a naturally occuring salt, and massively used as a fertilizer, so that shouldn't be an issue as well.
Industrial amounts of said wastes would instead certainly have to follow specific disposal guidelines.
Do not try this at home using pottasium nitrate , this chemical Is Extremely dangerous , use sodium hydroxide with Sodium nitrate and sodium nitrite , lot less risk to your health which is not pointed out in this video
@@beyond.ballistics Potassium nitrate , when heated release very toxic fumes , he has not mentioned this in detail , the fumes should be extracted properly this video should be taken down as there are less dangerous alternatives to blac metal using sodium hydroxide , sodium nitrate and sodium nitrite , gun smiths no longer use Potassium Nitrate because of the dangers to health and high risk of developing cancer in humans .
@@KS-bf7si It does not in a 130 degree water solution. It is safe from that point of view. But if you loose too much water and it crystalizes on the vessel walls heated by something that can raise the temp more than those 130 than it can be problematic. In BB's vid he uses a hot plate, which is great, I would say that doing it over a gas flame would be something else.
I’ve got a 1940 mauser made Luger that unfortunately was chrome plated at one point. It appears to be chipping off at the muzzle and some small areas. For a historically accurate restoration I’d need to salt/hot blue like your video. Do you know of/have a preferred method to cleanly remove chrome plating without damaging the steel? Great content as always!
Can we blacken Stainless Steel 304 using this method? I'm trying to get some SS304 screws to be black/grey
definitely not. There is unfortunately no easy way of bluing stainless steel with black oxide. What can be done is applying an iron electrocoating on top of the stainless and then blacking that one normally.
@@beyond.ballistics understood. Thank you so much for your reply. And excellent content. keep up the good work.
What about disposal of the solvent?
Brilliant explanation - thank you
What is the recommend way to dispose of left over solution? Thanks for the video
Thanks for sharing, you are the real deal!
Where is the video for the last blueing method?? Very excited for it to come out.
Grazie mille.... Like always we Love your videos....
I used to do this in a gun factory and mixing the solution and boiling it is very dangerous it can erupt like a volcano if you do it wrong, i cant remember the correct proceedure but you must find out before trying it.
0:57
Ive burnt 4 fingers of my hand and 2 fingers of foot twice while having dip bluing as shown above . The pain is very intense .
very good information, thanks for the video.
one question, after following the whole process step by step, when removing the pieces from the solution there is a black residue that is easily removed, what is the reason for this residue? is it normal in the process?
What did you say you add after the sodium hydroxide, I cannot understand through your Wales accent.
thanks for the vid and your trouble.
Will you do a cold bluing video for those of us without the space for all this setup? I have a precharged airgun where someone's carefully scraped the blueing off the air chamber and barrel but I think the quality of seals and threads etc will be hard to maintain with even the caustic bluing, also I don't have the space (or balls) for a 3 foot long boiling container of caustic pain! 🙂
Cold blueing does not compare to hot bluing , cold blueing wears of very quickly and you cannot produce the shine that can be achieved by hot bluing , that said , hot bluing is extremely hazardous to health y parkerising using manganese phosphate is a safer option.
Is the potassium nitrate necessary?
why do you pickle the part can it be done without it
dear sir, i like your video. I need to know one more thing that how to clean the factory made barrel before going for bluing ?
we are trying it by acetone and sanding but we see sanding impacts the steel at few places ...
is there any effective way ?
You can use a 10% sodiumn hydroxide solution for preliminary degreasing, before the acid pickling.
Fantastic ad always! Is there a way to obtain one of your T-Shirts? I love tge design and would like to support the chanel 😁
can i do this without KNO3
Will this cause a hardened surface to lose some of it's hardness?
No, it won't. The temperature reached by the bluing bath should be kept between 125 and 160°C, and must never exceed 180°C. No steel mechanical property is affected at or below those temperatures. The rule of thumb is to start worrying about messing with the heat treatment when you go above 200°C.
So, is the HcL just a degreaser? Or is it chemically critical to the process?
is it possible to use this method with Guitar Strings?
where do you get your boiling containers? homemade?
That's simply a 1.5mm mild steel sheet bent into a U shape with two caps welded, that I got made by a local steel supplier. You can probably buy an already made one from some gunsmithing supplier, but out of the US they tend to be hadrly available and quite expensive. If you're bluing smaller parts, a stainless steel pot will do the trick.
@@beyond.ballistics In the caustic solution a stainless steel container can deposit flakes of stainless onto the part being blued. Brownells literature warns to only use iron or steel for the caustic tank. Stainless is OK for the cleaning tank.
Stunning video as always. If I need to remove the old bluing from a gun that has been badly reblued by someone who had no idea, would you suggest placing it in hydrchloric acid? I remember seeing a video using this technique but I'm a bit worried I might etch the steel... I already tried with citric acid (first at 10%, then at 30%) but the bluing is not moving from the gun... Any suggestion?
10% citric should remove the existing bluing in a few hours. If it doesn't, either the surface is still oily, some form of coating was applied to it, or the black you see is not bluing or some other coating.
Try scrubbing with acetone and redoing the citric test, adding a bit of dish soap into the solution. If this doesn't work, it's definitely not a normal bluing.
A quicker acting, but still safe to use acid is oxalic acid, 5%.
@@beyond.ballistics i missed the notification for the comment, thanks a lot for answering. I didn't think to degrease the surface, I took for granted that the citric acid would work even if not thoroughly degreased 😪 my bad then, the revolver was a Bodeo from 1921 (Tempini) and I assumed it was blued, didn't seem parkerized at least... I'll try again after a few hours in brake cleaner
Nice
Hi Ballistics, what oil do you use at the end of the video?
How about a Parkerization tutorial?
I'm already working on it, it could be the next video on this channel
Inherent Black Bluing superiority
So, does this hold up to a cotton buffing wheel? (note: *without* polishing compound)
Or is it like cold bluing where it can be rubbed off; easily removed by buffing?
Also, does bathing the item multiple times help or will that lead to etching?
This is a proper black oxide conversion coating, so it has the same wear resistance of regular bluing. Actually most black oxide finishes, including gun bluing, are made with this process.
Cold bluing is instead chemically different (coating of copper selenide) and much less wear resistant.
@@beyond.ballistics Gotcha, thanks for the response!
Speaking of which... Not sure if this info is if interest...
I have some old 90's (80's, maybe) Cold Blue of _Van's_ that my dad had. I looked now online and the Contents are *vastly* different.
*NEW:* Selenic Acid, Copper Sulphate, Phosphoric Acid, Bonding Agents
*OLD:* Selenic Acid, Copper Sulphate, Phosphoric Acid, Ethylene Glycol, Iron, Magnesium, Chromium, Nickel, Aluminum, Tellurium, Bonding Agents
Like they say... _"they just don't make this like they used to"_
While I don't have any of the new stuff to compare it to directly, one sure can't help but think that the fact the old stuff had SO many additional metals, that it would've provided better protection! 🤷♂️🤞
Granted, the proportions are unknown, but I'd wager it's like food ingredients labels, where the concentrations are listed Highest to Lowest. It could still be (and likely is) only a small % of the now-missing agents, but it's a start!
Pretty wild that it has _Tellurium_ though (which is what makes me think it could be from the 80s)... 🤨🥴
Coming in late, I can't see any reason to use a buffing wheel on a blued/black oxide surface. All polishing is supposed to be done before bluing. Only oil and a cotton cloth should be used after bluing and then not a polishing action; just to apply oil to prevent rust. I've been a teacher for community college gunsmithing classes and taught hot bluing as part of the curriculum.
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In your formulation could sodium nitrate(NaNO3) be substituted for potassium nitrate (KNO3)?
Yes it can. Actually most commercial solutions use sodium nitrate instead of the potassium one.
I only used potassium nitrate in the tutorial because it's usually more common. You may need to adjust the amounts slightly.
Many thanks
Do you need to wear masks with these techniques if so what level of protection? 👍
The only time when there are airborns is when handling dry caustic soda. Once it's dissolved there is no breathing hazard. What you need to be protected from is the liquid accidentally ending on your body.
That's 40 grammes or 400 grammes?
👍🏻
tldr: i do not want to try that
That understandable to be honest 🤣
Bayonets ruined :C
Ohh that is a SHITLOAD of NaOH no thanks hahahah
Wow what a competent gay man.
he seems very happy with his work!
I would be gay and joyful
if I could have a nice workshop
to play with old fellow toys.