BLACK STEEL in 10 minutes: CAUSTIC BLUING Tutorial (with Household Materials) 

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.

This is a newer, secondary channel, but yes, you are correct.

@@addmix correct on both counts :D

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.

I'm very glad it is!

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

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

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.

You can use a 10% sodiumn hydroxide solution for preliminary degreasing, before the acid pickling.

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

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.

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.

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.

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.

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.

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

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.

I'm already working on it, it could be the next video on this channel

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 understandable to be honest 🤣

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.