Best Way To Blue Steel? Cold Blue, Hot Blue or Rust Bluing.
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- เผยแพร่เมื่อ 13 พ.ค. 2024
- G'day everyone,
In this video I want to show to show you a small experiment that I have conducted since mid January. At the same time that I nickel plated the tool holder, I also blued up several test pieces to test out various types of bluing. Bluing is a steel surface treatment, mainly used to cosmetically turn it black, but it also can provide some level of rust protection.
This is usually done by leavening it baths of very hot sodium hydroxide, which is very dangerous and I would discourage that process to be done in the home shop.
However there are several other methods that can give similar finishes and corrosion protection. These include hot oil bluing, cold bluing and rust bluing. However each of these have associated pros and cons.
Timestamps
0:00 - Intro into bluing
2:50 - Cold Blue
7:50 - Hot Oil Bluing
11:33 - Rust Bluing
13:52 - Corrosion Resistance Tested
14:41 - Hot Caustic Bluing - วิทยาศาสตร์และเทคโนโลยี
I am a gunsmith. I have done the hot caustic hot bluing. It is a long an complicated and expensive set up with specialized equipment. Mine was heated by propane, of which it used a lot. Most all alloys of steel came out with a rich deep black, some came out splotchy, very ugly, even odd colors like green and pink ! Stainless steels have their own special mix of bluing salts. I blued so many in my area, that it became unprofitable to keep renting the propane tank for just one or two a year. Do not get into hot caustic bluing unless you can justify a continued need.
There are specialized tool blackening ( cold blue ) chemicals that can be bought that do far better than the one in the video.
Also, there are special paints that can be air brushed on,and baked in an oven.
Can you do things cold and have the surface be food safe? I want to be able to cut an apple with my coated blade and not get selenium poisoning
Yes i have watched it done and it is not fun, however, as you no doubt know, the finish is fantastic and when done properly very tough. The best bluing I have seen is on my Model 80 J.P. Sauer. As with most things, preparation is everything. Way back (45+ years ago) i bought a 308 CZ. They were cheap, reasonablly accurate and properly machined where necessary but poory finished. I finished the action with hand files, abrasive papers and diamond grits and had it blued. The gunsmith pronounced it worthy of him applying his craft to it on my third presentation of the gun for his approval😗. I learnt a lot from that little exercise, it took a lot of time to get it right but the end result was worth it.
For those who want to try it, bluing is like a high gloss finish, it will expose every little flaw and mistake. In my experience, it is far more intolerant of mistakes than a plain polished metal finish.
First thing, have a very good light in your work area.
A couple notes that have helped me with rust bluing. 1. Light coating with the rusting solution you mentioned, then let it dry with a fan or blow dryer. 2. I will let it boil for up to 10 minutes if it isn't converting well. 3. I use very fine steel wool or even denim to card off the surface after boiling (carding wheels can be purchased). 4. I only use distilled or RO/DI water to boil and I change the water frequently because it becomes contaminated with the rusting solution. 5. After I repeat the process many times (up to 10), I card the part one last time and soak in kerosene overnight. The bluing becomes much darker and more stable after the kerosene. Then it is safe to oil it with something heavier. If you skip the kerosene and oil it right away with something containing detergents, you may run into issues. I hope this helps anyone, I've gotten some really great finished from this process, even darker than what I get from my parkerizing setup.
Parkerizing is faster and less labor intensive, especially if you have a sandblaster. But the convenience of being able to DIY rust blue in your kitchen is a skill worth knowing. Also if you have a rust blued part that does start to rust again. You just degrease, boil and card the part to convert the rust.
I heat up some linseed oil for oiling .
The high temperature let the remaining water boil of
The oil dries after whiping of the oil.
The are dry to the touch after 2 days or so
Very similar to Mark Novak's method from his TH-cam channel
Few more sugestions...
As usual.. devil is in the details :)
Part need to be extremly clean before you start.
Acetone is prety OK, but any solvent will inevitably leave a very small diluted amount of grease that is just smeared over the part.
I found that Dan Gelbarts method with ligyid ajax (very light abrasive/soap for the kitchen), work the best.
Water myst "wet" entire part, without any spot that repell it.
Do not go for quick rusting.
Actualy... the proces is called "slow rust blueing". You need some very mild acid, so it will create very thin but also very uniform coat of rust. Uniformity is the mailn goal.
I used very diluted ferichloride (chemical for etching circuit boards). After covering part with very thin layer of it, hang it in a bucket that have some cold water on the bottom (part shouldnt touch the water of course), cover and leave overnight. Wather should be cold so you do not get imediate condensation on the part that will produce dropplets of water and consecvently not uniform coat of rust.
In the morning you should get very thin, but very fine and uniform coat of rust. Almost like you "painted" it with rust.
After that, boil in demineralized water as mentioned, not in the tap water.
And do not just slpash the part in the water, it should be hanged in some way.
Then you need to card it, but not with skotchbrite or steel wool. You need "card brush", the brush that have very fine steel bristles (under 0.1mm diameter, for example Brownells have them), or similar dremel wirewheel (jewlery supply store have them). JENTLY brush the part, cos your goal is to just remove partticles that are loose.
Rinse and repeat...
I manage to get some realy deep black cover, after maybe 3-4 cycles, on free machining steel.
After all... some of the best "fine guns" like H&H are done this way. Only reason that hot caustic is used in industy is that it is cheap and quick on large scale. Much cheaper than slow, long rusting process, that require skilled craftsman.
But when done propperly, slow rust blueing produce incomparaby nicer finish, that will last.
Good comment. I made a steam pipe with a bit of wood stove chimney atop a spaghetti pot. Steam is aways clean so I use less distilled water. It's a lot of polishing but very rewarding! I think the kerosene step is to allow the magnetite to really "settle in deep", whatever that means. But I agree. Kerosene or non-detergent motor oil. Beautiful finish, hard as heck.
to my eyes, the rust bluing looks the best... *old school!* 🤩👍
Everyone of those types of blueing must be cared for or rust will form. I gave them up long ago. My go to metal finish for steel is parkerizing. If you can heat water you can parkerize. The military has required it on all their small arms in both world wars. It is extremely resistant to wear through on high points of frequently handled parts unlike blueing and hides machining marks really well. The finish is a matte grey and if you prefer black you simply add a little cold blue to the solution. It stores indefinitely in plastic jug(s) until you want to warm it up and use it again. Parts should be degreased, but they need not be polished as the finish is matte. You can even sand blast the parts if you want the parkerizing to get a death grip on an item for generations to come. Check it out. You won’t be blueing any more.
I've looked into this many times in the past and my best research has always told me that Parkerizing is proprietary and there's no way to do it in the home shop. You got a link?
@@brocktechnology If you're in the U.S. Brownell's had the chemicals and instructions. There are other places but that's where I got mine. There are two different chemicals with different colored results. The gray/green is zinc phosphate (Parkerizing) and the black is black manganese. I heat the solution on an electric hotplate but that limits the volume I can work with.
@@brocktechnology "Mark Presling" - "Metal Finishing 3 Ways - How I Finished the 4 Facet Drill Grinder"
@@brocktechnologythat may be because "parkerizing" is a trademark name, the real name is phosphating or phosphatizing and it's extremely common in an industrial environment, and the steps are beyond simple to do even in a domestic environment
@@jrkorman ditto that on the link to Mark Presling. He’s a retired high school shop teacher, and he’s absolutely brilliant! Once you watch one of his videos, you’ll find yourself wanting to check out the rest.
Look up beyond ballistics, its backyard ballistics second channel and he made several videos on bluing and goes into more detail. It may help if you still need info.
Backyard Ballistics is amazing
Absolutely agree. His stuff is literally museum quality, but he also tries to make everything actually function. Beyond Ballistics also has an entire video about caustic blueing.
Could you get a large flat fish bubbler stone...put under the part to nickel plate...then bubble air past the part, this would agitate the fluid and help cover better
Very nice on the finishes!
Awesome!
Keep em coming!!!!
Ha, I was thinking just the opposite, to do it in a vacuum chamber
This. I worked in industrial plating for a few years. All solutions have bubblers and circulation. The current control is something that isn't given enough attention. The bubbling from the parts is a sign that it's being over driven. I did a lot of reel to reel plating back in the day. Millions of chip legs passed through my tin-lead line back in the day. I think the rolls held 50-200K legs per roll.
Air=a very good electrical isolator! Also: a wonderful oxidizer, which is not good
Pumps or stir bars are the way to go. Tin/Lead != Nickel and in a industrial galvanic setting there are many different steps, including washing, passivizing or harmonizing, where some kind of gas-bubbling will be helpful for the process. Please RTFM (meaning a suitable specialist book on the subject of galvanization/electroplating/chemical galvanization. This saves a lot of trouble, cancer and hair loss;)
P.S.: Plating on an industrial scale and quality, like drum (electro-)plating, is of course complete nonsense at home. That would be uneconomical, unaffordable and, above all, illegal because you wouldn't be able to get the necessary permits for it. Note: Such a system includes water treatment and disposal facilities, which are usually 10-20 times larger in volume and area than the actual production system where the workpieces are handled. Also, you need a separate department with trained chemist(s) on the facility that check the quality of the production equipment and the safety of wastewater.
I don't recall whether or not we used air agitation in our _nickel_ tanks, but I do know that it is very important to have sufficient anodes placed throughout the tank around & in-between the parts being plated. I spent most of my career supporting the plating shops where I worked my entire career -- we did "industrial" plating, not "cosmetic" plating. At times we'd have to apply more than 1/16-inch (~1.6-mm) thickness of nickel to build up worn parts before grinding & then chrome plating on top of the nickel for wear resistance. Anodes of the correct shape, placement, & spacing, at least for chrome where the anodes did *not* supply the metal being applied to the part surfaces, were critical for even thicknesses of chrome in this example. The same works for nickel plating, except that the anodes would have to be continually (machined &) replaced which cost way too much to be practical. By chrome plating surfaces evenly, we cut finish grinding times to less than 7% of what they had been before using "conforming" anodes. With nickel and thick deposits, we found that even though it wasn't cost effective to manufacture custom shaped nickel anodes, custom "masks" worked almost as well. Of course, "Artisan Makes" isn't even fantasizing about industrial plating in his workshop, but some of the ideas that were successful in industry can still be adapted to work in home shops too. I think that I would try air agitation with nickel plating, unless I could find my copy of the process specs we used at work and they said not to use air. The only agitation we used in any of our plating tanks (we had over 200 tanks between our two plating shops) was air, pumps, and in a few cases, propellers to stir the solution up.
Huge fan of your channel here. I have some experience as a gunsmith and in teaching gunsmithing classes so would like to offer some additional thoughts.
As others have mentioned, Parkerizing is a very viable alternative. It is best done to steel that has been blasted with aluminum oxide first, then degreased and Parkerized. That will give it the texture that promotes oil retention. Zinc Parkerizing resists corrosion much in the same way that hot dipped galvanizing does, by attaching zinc to the steel. It’s a simple process done at about 160°-170°F/71°-77°C. When the part being Parkerized quits bubbling, it is done. It’s easy, relatively inexpensive and an excellent method of preventing rust. It is not suited for precision surfaces.
Cold blue is just a change in surface color; nothing more. It's caused by the very toxic selenium in the solution. You're correct that the brand you used is not the best. "Hot oil blue" would be a better description for that process. Gunsmiths use the terms hot bluing and caustic bluing interchangeably. Cold bluing can be improved somewhat by gently warming the piece to around 140°-150°F/60°-65°C before applying each coat.
Your “super slow” rust bluing method was done far too fast. For firearms the steel is allowed to rust overnight in a humid environment before boiling and carding. The extended rusting time permits deeper penetration of the iron oxide.
Having done a lot of hot caustic bluing in a correct environment, it is not the best method for home use. The correct temperature is actually 201°C/395°F and is controlled by the concentration of salts in the solution. Contact with hot bluing salts will result in severe heat and chemical burns and it can destroy eyes.
I've had good luck with Parkerizing steel parts, also known as Phosphate coating. There are 2 main types, Iron Phosphate and Manganese Phosphate. If you see a recipe for phosphating that calls for Manganese Dioxide (by harvesting it from alkaline batteries) then it's is not Manganese Phosphating, and you end up with a light gray Iron Phosphate coating. Manganese Dioxide is non-reactive in most acids.
I worked with a chemist friend before he retired, and we found a method that works. If you can get the materials, then great.
You need a solution that is 1% phosphoric acid, 0.2% nitric acid, and 0.5% manganese carbonate (MnCO3). In a stainless container I heated 1.5L of water to 95C, then added the phosphoric acid, the nitric acid, then the manganese carbonate. When dissolved and the temperature stabilized, I submerged the parts in the solution for about 20 minutes. The part was then dried, and coated in oil for a nice dark gray to black finish.
Gun smiths used to use "rusting cabinets". They'd place barrels & actions in wooden cabinets & and then through the boiling and polishing process.
Former R&D director at a cutting tool fab shop (my main job was reverse engineering cutters for GM / Bombardier / Honda etc) All of our bluing was cold - we didn't brush it on, we had a tupperware container of the stuff and the parts got submerged and agitated. The liquid will gradually turn from blue to green, to a bit yellow. A 300-400ml container would last hundreds of parts / more than a month of constant use, it just might take a few extra seconds. Once the solution starts to go neon (green / yellow), finished parts will have some brown sludge form on them (over the black) that can be rubbed off during oil application. As mentioned in other comments, parkerizing should be the go to for longevity without as sensitive a need for constant oiling (the phosphorous of the surface treatment when exposed to moisture it will release phosphate ions into the water producing phosphoric acid, which inhibits oxide formation, and converts iron3 oxide(brown rust) into iron2 oxide (black rust) which is much more soluble and washes off). It still needs to be oiled to make it last, but the magnetite / selenium foam of 'black oxide' trying to hold oil just doesn't compare.
- Just checked, completely forgot you can soap parkerized parts lol, basically galvanizes the thing.
Cool comparison. Thanks for the video!
Great video and narrative on the different effects and processes. The comments add a lot of additional information.
Thanks for sharing everyone.
The best things I've found for Cold Bluing is a _Syringe_ and a small _Foam Paint Brush_ or alternatively a wad of Raw/Unspun Cotton like Cotton Balls.
The Syringe lets you apply the solution directly to the Foam Brush so you don't have to worry about wasting any as you can just add any unused Cold Blue back to the bottle, and the Foam Paint Brush holds and applies the solution much better than a regular bristled brush does. 👍👍
Im a gunsmith that quite frequently does hot caustic bluing. Id like to have seen you do it as well. Its also not very difficult to do as most people think it is.
It would be time consuming, but if hot oil bluing is the same as seasoning a cast iron pan, you could also try treating your parts the same way you re-season a cast iron pan: clean thoroughly, wipe on a layer of oil, wipe off ALL the excess, and bake in the oven at around 180C for half an hour or so. Repeat until you're happy with the coating. For cookware, flaxseed oil seems to work the best. Note, it really is important to wipe off the excess before baking; a few-molecules-thick layer will correctly polymerize, while a thick, drippy layer will just turn into gummy tar.
I like to keep a small piece of Scotch-Brite coated in a little 3 in 1 oil. When I get a small rust spot on a tool (or when they need a bit of a clean), I just give them a scrub with the oiled pad and a paper towel. Job done. In my pea brain, the Scotch-Brite helps dig the oil in to the metal and leave a protection.
Have you looked into parkerizing? It's easy to do in the home shop, and the chemicals are readily available and reasonably safe to handle.
The finish is extremely corrosion resistant and durable.
The only downside is that it does add a very small amount of material to the part, so it can affect the fit of parts with very fine tolerances. Not an issue for most tools though.
Method I have found to be the best is dipping the part cold into molten potassium nitrate. By the time the part has come up to the temperature of the nitrate it is done. Gives a rich S&W dark blue if the part is polished up before treating. The colour can be adjusted by adding a pinch of cement colouring.
Another great video. I have experimented with Hot Bluing with good success. Pretty easy to do and definitely helps with the rust. Love your videos. Cheers.
Great video. I have found "Oxpho Blue" works much better than Birchwood Casey's cold bluing compound. Keep up the informative content. Also, heat the part in boiling water rather than using a torch. It will give a much more even heat and hence a more even finish. Thanks.
👍🏻 Fascinating, thanks! And it helps explain how i accidentally blued some stainless steel tableware. I usually soak used tableware (especially if it's greasy) in a tub of washing soda (sodium carbonate) until the dishwasher has a full load. But recently i ran out of the washing soda and used some caustic soda instead. And presto!
There are different cold blues, some don't get as dark, some get very blue (Presto Mag). Super Blue has some copper compounds, making it slightly blue and lighter, some that don't have the copper salts or acids added will get much darker much more quickly, but it feels like the copper also adds some weard resistance, the Super Blue is much harder to scratch off than the Ballistol one, that does have the same ingredients minus copper compounds.
There are 3 from Birchwood-Casey, all with slightly differing results. I have used SuperBlue and PrestoMag and the Presto gets a really strong blue sheen. But it all depends, they also look different on different finishes.
This video came out at the PERFECT time for me. I have been working today cutting and drilling some steel plate and had in the back of my mind how was I going to keep this from rusting. Super Blue has been ordered and will be here in a couple days. Cheers!
Pretty nice testing and comparison, dude! 😃
Another thing to consider is the temper. A blade, for example, that needs to hold a sharp edge, can't be heated. So, in that case, I'd go with the cold bluing. 😊
Anyway, stay safe there with your family! 🖖😊
Caustic blueing with linseed oil is my go-to method. I use a solution with ammonium nitride as an oxidizing agent. You can boil it outside or under a fume hood. Linseed oil applied afterwards is drying oil, which will act as a thin solid layer further repelling moisture.
Excellent. Please also consider evaluating “nitre bluing” or “salt bluing”. Brownells in the US sells bluing salts for this purpose (sodium nitrate, sodium nitrite, and potassium nitrate). You simply immerse the part in the molten salt.
I’ve done it with potassium nitrate stump remover. Pretty quick, durable, very black.
There are several recipes for caustic bluing. Some better than others. I've seen a couple of guys on the Tube put out some really nice finishes. Most were gunsmith related. I don't think all of them require sodium hydroxide, either. Rust bluing requires quite a bit of patience, as I am sure you found out. Nice work, though.
Did hot blueing at school 50 odd years ago, we used a special blueing oil and it worked really quite well. Hasn't worked for me since and cold blue doesn't cut the mustard. I'll be trying parkerising next, following seeing Mark Preslings video on it.
I did something similar to the hot bluing,
I was making hardware pieces out of a higher carbon steel. After shaping I heated to red hot and quenched in used motor oil. They came out with a very nice black finish and good rust resistants
It is a good finish but isn't good for precision pieces as heating to red hot can cause warping or distortion which may require grinding to restore precision.
I never have tried to blue anything but decorative or ornamental pieces, but that's always been my go to. I suspect the used motor oil makes the parts darker because of the carbon/soot in it from engine combustion.
If you want to try this, lawnmowers usually run non detergent sae 30 oil, and it usually doesn't get changed regularly, so there's your potential source.
If you don't have a lawnmower, I'd bet one of your buddies would love to let you change his lawnmower oil for free. $10 and 15 minutes and you have your blueing solution.
Cold blue is my usual go to. For small parts I usually add a little to a dish and roll the part around or submerge it.
Hot waxing/oiling/blueing is a common traditional blacksmithing technique, and is really easy and consistent if done right.
Instead of dunking the whole part at a very specific temperature like you're doing, consider getting it a bit hotter and rubbing the polymer on with a cloth or straight from a wax block instead.
Welding or hot mill gloves should handle the heat no problem
i've seen a ton of ppl do this & was rly surprised to see a full quench/dunk! you could also just straight-up season it in the oven like a cast iron pan, that would avoid thermal shock
Good vid. Cheers.
If you want to try more hot oil blueing maybe look into using grapeseed oil over linseed, that's also commonly used with cast iron pans.
It has a higher smokepoint, i think around 230° and generally just is a lot more robust than linseed in my experience.
I put an old socket that I'd found rusting in the dirt, outside of our old shop, into a container of vinegar with some other small parts. It got missed when I retrieved the parts, and the socket sat in that vinegar for about a month. When I found it again, it was solid black and deeply pitted. I rinsed it off, dried it thoroughly, and oiled it, then I soaked it with WD-40 before putting it on a shelf. Years later, the rust has yet to return to it. This is not a climate controlled building, so that socket is still subject to condensation and other factors that come with that inconvenience.
I vaguely recall that Randy Richard did a method of bluing that involved suspending the parts above vinegar, plus leaving the (closed) containers in the sun to fill the space above with fumes. It seemed to produce nice results, but it was a time consuming and slow process. It was quite a while ago when he did this, so you will have to go way back into his archives to find it, if you are interested in researching it.
one of the solutions that I have used at the machine shop for blackening mild steel parts that are going to be exposed is to use Beeswax, Turpentine, Linseed Oil in a 4:2:1 ratio, mix and stir until its a gel consistency. Sometimes I will add ebony furniture stain to the mix. Heat the parts to 300 degrees, I use an old toaster oven. Make sure they are properly cleaned first, then submerge them into the can of blackening. Remove and rub down after 5 minutes or so. Repeat if necessary. It holds up pretty well, I coated hammer heads, shovels etc they show minimal rust. If its a big item i use a torch head to heat it. The bonus of having a small oven in a machine shop is there are other finishes that can be done in a small shop that using a dedicated oven would allow. Look at Cerakote, they have some great applications that can be done in a small shop.
An interesting video.
Depending on where anyone lives, it might be possible to find a small gun shop who do have there own hot caustic bluing tanks. If you do the initial polishing to the level you want, the costs would be very cheap if all there doing is running them through those tanks. I looked into setting up a small system to do it at home because of the much better professional finish quality and it's durability. Frankly it needs to be either in it's own separate building or done outside. Even the fumes from the process will seriously rust anything anywhere close to the same location. It will also after using it enough, even start to degrade any wooden structure. I could afford to do it, I just don't want the extra issues that come with it.
Luckily my own small shop is inside my home and has the same conditions as far as being a semi controlled environment. I also live in a fairly arid area, so tool rusting has never been an issue. In the summer, my inside humidity levels average about 30%-40%. In winter and with the heat on, that drops to an average of 20% - sometimes as low as 9%. The only evidence I've seen of actual rusting is on a bar of 12L14 I've had sitting in my metal stock for over 25 years. But that alloy is well known for how easy it does rust. Even then it still only shows a few light areas.
But I try to look at problems like this logically. Machine tools and all the required tooling quickly adds up to a decent sum. I've also seen large numbers of pictures in UK published magazines that show huge amounts of rust over almost everything. For whatever reason and using what they refer to as a garden shed or separate out building on there property seems very common. And going by those various pictures and in some YT videos, few seem to be ever insulated with vapor barriers or have anything like constant source of heat during lower temperatures. It's always seemed highly counter productive to spend what this costs and yet refuse to insulate to slow that humidity and reduce those non optional heating or air conditioning costs. And in those high humidity locations, I'd not hesitate to also add a dehumidifier. Any unheated area will go through the same temperature swings as the outside temperatures do. So anything made of metal takes a whole lot longer to thermally stabilize. That causes high humidity to condense on the surfaces and that's what causes the rusting. While I fully sympathize with anyone having to constantly deal with that humidity, tying to band aid and work around the problem is only treating the symptom and not addressing the root cause. Bluing parts does look proper for a lot of items, but for myself it would be for aesthetic reasons and far less about any rust prevention.
Canola oil straight from Woolies lmao. Doesn't get much Aussie than that. Loved ya video mate. Cheers.
Hot bluing is actually pretty easy, just storing the solution is pain. Blued whole air gun in welded stainless steel container over electric heater, and temperature doesn't really matter, just add slowly water when it starts to boil.
I've done both caustic as well as nitrate process. I've also done a few other heat related processes. FWIW, the caustic process isn't as nasty as it sounds, it's roughly ~350F. I used to have a mix of potassium nitrate, sodium nitrite and sodium hydroxide with a very tiny amount of water in a stainless steel pot on a hot plate I would use for dipping parts. It is definitely the superior method as the molten salt pretty much saponifies any remaining oil, and converts any oxide to Iron II oxide. It doesn't outgas, you just want to have some careful controls on how things are going. If you want to try it yourself you can use a stainless steel or cast iron frying pan, fill that up with about an inch of sand, and then put a small stainless steel pan in the middle full of your bluing salts. It takes quite a while to get up to temp with the extra mass, but it also thermo-regulates itself and you can use a kitchen gas flame for doing that. Read up on it, check out some of the chemistry vids out there, it's much less exciting than it sounds.
The other process is parkerizing, which is done at boiling water temperatures, but uses phosphoric acid, manganese dioxide, and some steel wool. It's harder to make it look even, and requires the parts to be degreased and bead blasted before processing. It does involve boiling acids, but it's not as exciting as it sounds, just do it outside.
Beeswax is a good alternative to oil for hot bluing. I use it for forged parts and it makes a very dark and durable coating.
An additional option:
Go to a crafts store and buy a few boxes of the oversized sidewalk chalk ...put a couple pieces in all your tool drawers ...the caulk will absorb the moisture to reduce it from being on the tools
one method i have found quite good especially for tools that are already a bit rusted is a soak in phosphoric acid. it will remove the rust, and leave a somewhat passivated slightly porous dull grey finish that takes oil very well and stays rust free for a long time. don't leave them soaking too long though as phosphoric does etch the steel a bit too.
ive done both hot and cold bluing, but im definitely gonna give rust bluing a try!
I've had impressive results from Brownells Oxpho-Blue at 85° F (30° C). 0000 steel wool buffing between layers. Hard black finish that stands up to wear.
I’ve tried parkerizing - easily achieved by a home shop and seems to give decent results.
The one you skipped was Bright Bluing. See Clickspring, it's actually a type of iridescence. Bright blue finish, it's a bonded oxide using carefully controlled heat. As witth hot oil blue, not suitable for heat treated parts
It's been my experience with cold blue that I tend to get pretty variable results with low carbon steels. I've played around with various brands without much noticeable difference. I end up applying and scrubbing 2-3 times when I really want it to look good.
i thought this was pretty cool! i've also seen hot salt blueing, though that might be kind of similar to caustic blueing.
I heat up some linseed oil for oiling .
The high temperature let the remaining water boil of
The oil dries after whiping of the oil.
The are dry to the touch after 2 days or so
Sodium hydroxide is lye - but not the only drain cleaner. Some of them are acids instead of bases. In the US, at least, you can get crystalized lye which would be pretty useful for small batches - and the added bonus that you could just pour it down your drain 😅
I use “rust converter”, a spray on chemical process that makes rust go black and adds a layer over clear paint over the top. Literally a few seconds and it can be applied again when it wears off. Alternatively, instead of oil use an oil with a rust inhibiter, way better than just oil.
You could also try salt bluing.
It is tougher than most of these options, and can be polished (unlike rust bluing which will stay a satin finish) but not nearly as dangerous as the caustic bluing.
I would be curious to see how bluing compares to applying a rust converter. For example, at 12:38, after you've uniformly oxidised the part, you can then just brush it with rust converter (NOT rust remover) to convert the Iron (III) oxide into an inert layer that chemically bonds with the underlying metal surface. Rust converters are mainly tannic acid or phosphoric acid based, with additives that promote adhesion.
I have had good results with Phospheric Acid, then oiling with a good soak period. I quite like the matt grey colour, but it can be tricky to get an even finish. I use it mainly for nuts and bolts where the uneveness doesn't show. If you leave the acid on too long it can develop a white deposit but you can scrub that off and recover.
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I have now started using phospheric acid the coating in a drying oil like Penetrol Rust Treatment. It's good for storage, but not great for wear items like hand tools.
Backyard Ballistics has great videos on these
I’ve done the caustic soda method before for a knife I made…
I wore a respirator but made the mistake of wearing a t shirt and man oh man did my arms light on fire when I was near the stove
Nice video, thanks :)
For cold blue on small parts, I have come to prefer the Birchwood gel. A smidge goes a long way. All the same processes, but you smear the stuff on the metal with gloved fingers and watch it work. I usually leave the parts until the gel is mostly dry and gummy, then wipe well and oil the parts to sit overnight.
I do cold bluing in a different manor. First, buy the ‘Presto Black’ by Birchwood. It’s the tool version, which is much blacker than the gun blue. It comes in a large white bottle for ~$60 (think per quart).
Then start the same way, wipe polished surface w/acetone and then wipe w/Presto Black. Then, instead of oiling, you use ultra light scotch bright yo lightly remove the first black. It’ll look like steel, but a bit darker. Then coat in Presto Black again, let sit for a couple mins each application. Then, the final step is oiling and letting it sit for a couple hours. Then, wipe any excess with a microfiber pad.
This will make a really nice and glossy finish that’s very black, as there’s no powdery buildup or rusty-looking portions, a product from the bluing remaining and allowed to react with the oil, more than the reactive surface of the steel allows.
I always preferred the look of blued tools. You should do a video of japaning
most durable bluing i've ever done for knives and wrenches i made on a waterjet: heavily sandblast the steel surface, then find a way to string the steel object on a wire. load up a spray bottle with denatured alcohol, and get good hard squirts into all the pores of the sandblasted surface. while you wait for it to drip dry, preheat a furnace to 960°F/515°C. once you hit temp in the furnace, quickly place your object in for just enough time to get it glowing red hot, without shedding scale off (otherwise you have to start all over) then quench in USED motor oil from a 2012 chevy colorado. The oil completely soaks into the pores of the sandblasted material and it makes a pitch black smooth matte surface (no gloss like your method) it doesn't chip and its very hard and scratch resistant.
Jane’s Kits in Melbourne make a heat-based Nickel coating that I’ve used. It is easier to apply than the electro-plating version and gives more even results, but you’ll need to modify a cheap hot plate with a temperature controller to use it. From memory I believe you need to keep the solution at 85 deg C for about 45 minutes. Also, I run a small desiccant-based dehumidifier in my shed 24/7 during the wet months. It costs about $300/yr to run, but it’s worth it for the peace of mind. My tools almost never develop rust unless I leave them too close to the floor. I think it’s an Ionmax ION610, which you can get for around $250 from eBay or $329 from IonMax
I run a dehumidifier in my garage in the UK. It does the trick and doesn't cost that much to run. But I actually like the finish on these blued steel.
on your cold bluing, there are two methods, the one you used, which is very expensive, there is another method that uses 3 baths, first a cleaner, second a blueing solution, and third a dewatering oil, this can get a deep black in one go, and the solutions can then be poured back into there storage bottles and used again and again until they stop working, this is the method I use, and a 1L kit has so far done dozens of parts, and if still going
*caustic :) parkerising and nitriding are the semi professional / professional options with the former being more home shop friendly.
Parkerizing ❤❤❤
The term for blacking steel is actually 'browning'. Perhaps it was invented by the poet..who knows..Anyway, the cold blueing stuff we used in the past was selenium based, and was really a very poor-mans substitute for the hot caustic process. Not only was it not at all durable, but it gave everything a foul smell, including the person handling it. It's said selenium can make your breath stink of rotten eggs, so I wouldn't recommend it. The hot process uses sodium nitrate, nitrite and caustic soda in the molten state with some water, at around 140C I seem to remember. If you can get hold of the chemicals in this nanny state, then I don't see why you shouldn't do it, as long as you're not one of those people who need to be warned not to eat their car battery. These days, my favourite is ....wait for it...the sand blaster and the blowlamp. I use kiln dried sand in a home made pot (ex- propane cylinder with a few extra bits, and of course the compressor). I blast the components lightly, to give them an even matt finish. It gets rid of any staining and light pitting/machining marks. Then I heat them up with a large gentle flame waving it around evenly and watch for the colour change. Once it start to go blue, that's enough, don't go to hot or the the colour fades a bit. It will return as it cools. I then let them cool a bit then oil them or dip them if they're not too massive. I also use a solution of beeswax in paraffin which dries off to leave a pleasant feel to them. The matt black finish is really posh. I love it. Oh, and before the safety elves kick off about the dangers of sand blasting with real sand, yes... I know. So I stand up wind, wear a mask, and don't do it every waking moment. I think the risks are greatly exaggerated even so, I mean the Bedouins spend entire lives tramping around sand dunes in the Sahara. They seem to survive. Perhaps it's sales bullshit so you buy the expensive 'proper' grit. A bit like why you must throw away the cold blue you've dipped parts in. Just bullshit.
Mark lee express rust bluing solution is pretty good for a nice rust blue finish
Just a note when i do firearm restorations i do rust bluing on large parts and Oil bluing on screws and small parts . When you do rust bluing it works better with steam versus putting it in water
I have seen someone on youtube make a bath off water and rust powder (I assume bought online for purity) and just dunk the part in it and boil it and it turned out really well
I always meant to try it but haven't yet gotten around to it
Ive used a laboratory hot plate to heat steel parts to blue them, Much easier to control the heat than using a torch. It does take a little longer though. Used the chemical blue as well, agree that it is not as tough.
its way better to rub the oil or wax onto the hot part with a rag instead of dunking it in a pot. Part not hot enough? will see immediately without having to start over. Coat not thick enough? apply some more heat and rub on more. No idea why the dunking method is the one shown everywhere
Would have liked more on Caustic blueing.
It's pronounced "mag-neh-tite". It's Fe3O4, and is the black/grey form of iron oxide. (Haematite is the red form - Fe2O3)
But we'll done on your bluing demo.
Arguably the best 'black oxide' coating is parkerising. It's also worth looking at the various types of 'wax oil' as longer term alternatives to the 3in1 oil. I'd recommend looking at Mark Presling's youtube channel for some really comprehensive guides to metal finishing in the home shop.
Parkerizing, whether zinc or manganese, is a very durable finish but it is not the same thing as black oxide. Either type of Parkerizing is much more rust resistant than black oxide bluing.
I used to get ph down (phosphoric acid) at Bunnings and manganese oxide from old alkaline batteries a stainless steel pot and a bit of fine wire wool. Produces a manganese phosphate coating that when neutralised and oiled was far more rust resistant than any blueing.
Have you considered building some speakers? I can really imagine it being an interesting project!
My solution for the rust problem in the workshop is to use a spray gun to cover machines and accessories with used hydraulic oil. Effective but much cheaper than Fluid Film or Boeshield.
Fun fact: steel can be anodized, just like aluminum or titanium. And the end result is essentially a kind of bluing.
You can also blue stuff with certain fertilizers, some sort of nitrates/salts. You can see it in some Kyle Royer vids where he blues handguards and pommels, but it does require a couple hundred degrees. I'm not sure how warping is, since I think you let everything air cool afterwards
Have you looked into parkerising? Preso, an australian TH-camr had done several Videos about Rust-Proofing and this is his Go-to method.
sounds to me like you need to invest some time into weather sealing your shop and maybe investing in a dehumidifier, otherwise awesome vid mate
I have used a method that I learned from watchmaker video.
and the results are awesome. But I have made some cold bluing with pretty good results as well.
First let me say, I am not a professional, and please don't do this inside the shop, but outside in the fresh air.
1) Heat the part up very hot with a torch
2) Dunk it in "old car motor oil"
3) Take it out from the oil, and use the torch to burn off the oil
repeat several times and you get a very nice and dark bluing.
4) Clean it and put some protective oil of your choice
Use proper protection and caution please
and if any part makes you uncomfortable,
don't do it.
Be careful and safe
I have done this several times with very good result, but like I said I learned it from a watchmaker youtube video ... I just can't remember the name of the video
Linseed oil is alright for blued stuff since it penetrates and hardens pretty quick
I'm going to caustic blue everything! The other warning about caustic blueing is it dissolves Aluminum! Great for cleaning files, not so much when you're using cheap pans... Fortunately I double checked beforehand.
For carbon Steel the combination of Fe3Cl and instant coffe works well.
Do you mean FeCl3?
I read in one gun magazine about rust bluing but I did not believed that low temp oxide conversion is possible. They used hydrogen-peroxide as rusting chemical. I wonder if it is possible to speed up rusting with electricity, if they remove rust is it possible to add rust by switching polarity?
NOTES
Hot Blue :
the tempurature is going to change depending on the oil used
the rougher the surface the better the blueing takes to the metal
Rust Blue :
the deeper the rust penetrates into the part the deeper the blue will penetrate
probably want to let the rusting solution sit for a lot longer hours vs minutes
before the hot water bath
Fyi, you can fix the stickiness on a cast iron pan and I would assume a steel part by baking it at 220 to 230 c for 15 to 30 minutes. It will cause the under polymerized oil to finish polymerizing or burn off.
For the boiling water method, isn`t it possible to create Fe2O3 using DC voltage? Maybe with eletric potencial in salt water or something. Using the part as sacrifice metal.
I find with the first one, birtchwood casy, that it way better to watch it off and let it dry out (can heat) otherwise it's still 'green' and more wipes off
Would it be worth using a dehumidifier in the workshop if it's sealed up halfway decent?
hot blue no doubt !
So, with the Sodium Peroxide and boiling method, do you need to do it multiple times to get the colour or to make the rust resistance better?
Dehumidifier for the workshop I think. 😉
When I was hardening a part I machined I forgot to clean off the oil before tempering it and it made the part a nice deep black color, id love to see if that's repeatable
Yes, that's basically the same as the second method he showed and exactly how you season a cast iron skillet!
The important part is just having the oil go on a part that's smoking but not ignition hot
A non-drying oil might suit blued parts best.
I have a question . I know that a lot of watch parts are heat blued (sometimes with brass shavings) what i primarily see as a act to make it better looking rather than rust resistant. But can than be used as a process to blue steel effectively in a home workshop?
Temper bluing is a _very_ delicate finish, you can almost smudge it off just by handling the part, I wouldn't suggest it for tools.
Hot blueing (actually blackening) can be easily done at home. Just put linseed oil on the part with a paper rag, then wipe it down, to remove everything you can wipe off.
Then put it in an oven and heat it for an hour at 300°C.
No effect on heat treatment, just a tiny bit of smell and no issues with too much oil sticking to the part.
Works great even on rusty parts, as long as you don't need a clean surface finish.
Yeah sure, no different to how I do my cast iron skillets. For me it probably would affect so of my parts, most case hardened parts use a low temp temper but I know what you mean
@@artisanmakestrue. However if you're talking about tools out of e.g. D2 you can just lower the temperature to 200°C to be on the safe side. But burning in that way will take significantly longer: 3-5 hours.
the hot oil blue is better referred to as flame-bluing, in my opinion, but i guess it has no proper name other than what you decide to call it? i enjoy heat treatment, polishing, and bluing. the different bluings dont all come out as polished as the bare metal was before, im pretty sure caustic bluing is the only one to keep the polish other than flame bluing. correct me if im wrong, but i think rust blue and cold blue make the surface a bit dull if it was previously polished/
Ammonium Polysulphide works well.