it's not easy being blue'd...

[Iron Bear]

I just finished my first knife (yay!), and I was like, hey, this is a great practice piece, why don't I complete it in every way possible. So I wanted to blue it to prevent detrimental rust and/or corrosion. I heard that you can blue metal by submerging the piece in acid, then transferring it to boiling water after a set ammount of time, usually a couple hours to a couple days depending on various factors. My knife was standard weldable mild stock. I forged it to shape, then ground and planed it as best I could. I then hardened it at a orange heat in water, then annealed it. After polishing it, I dunked it in tetrachloride phosphate and some sort of ammonia and waited about 6 hours, after which I transferred it to boiling water. My result was: the water turned blue but not the blade lol. Am I barking up the wrong tree entirely as far as methodology, or am I just not doing it quite right?

[David Einhorn]

I recommend trying gun bluing at your local gun shop or from BROWNELLS . Wipe on, wipe off, done. :D

[bigfootnampa]

I hope that you meant "tempered" where you wrote "annealed" because annealing heat treats the metal to its softest state. Mild steel has a smaller variation in hardness than higher carbon alloys but even so it does make a difference. There is a lot of info on heat treating in the blueprints and the stickies in the knife forum.

There are lots of techniques for bluing but the one that you tried is a new one to me... doesn't look like it works so well either. I'd go to the blueprints, archives or google.

[Iron Bear]

Yeah I actually did anneal it, because I thought if the metal was softer it would somehow blue better? (I don't know how I thought that...) But anyways, ya, I was going to put it through another heat cycle after I was done to get the hardness back up. Didn't realize until later that another heat cycle would probably take off whatever blue got on there to begin with. But, like I said, it was my first knife and a practice project. I learned a lot of things and killed a lot of false notions about stuff, and I was still pleased with the results. I'll try to put a pic up once I finish the hilt, pommel, and handle. Just last night I made my first pair of tongs - I'll try to get a pic of those up too.

[Iron Bear]

TY Unicorn, I haven't gotten the gun bluing yet but I looked it up and it really does look incredibly easy. I think I'll go that route lol.

[John B]

Hi Iron Bear, if you are using standard mild steel weldable stock, did you get a satisfactory hardness to the blade? and if so how did you achieve this?

Normally I would not use that spec metal for a working blade, good for a forging exercise, but not an effective working model, others may have a different opinion and no doubt put their opinions forward

[Iron Bear]

I did not get what I would think would be satisfactory hardness to it at all. I quenched at an orange heat in luke-warm water twice, once before I softened it and then once after. The reason for the two quenchings was because I thought by softening it the bluing would hold better, but this was not necessarily true. So I quenched it again. As is stands, the blade will probably not hold it's edge and is not truly a working model. As my first knife, I actually didn't expect to do as well as I did. I just finished roughing the handle out today on my lunchbreak at work and I though it looked pretty good! (Reason I'm doing a lot of the work at my workplace and why it's taking so long is because we haven't moved yet and I don't have my shop yet lol - I don't have any stationary power tools at home).

[Iron Bear]

I was just reading another thread and apparently the technique I heard about for bluing is called rust bluing. It does work, I was doing it wrong, and it's better for fittings than anything, but you could use it for blades. I'm going to have to do some more research on exactly how to do it correctly, but it sounds like a viable technique. Only thing is using gun bluing that you can buy in a store is probably a lot easier.

[John B]

You could always use this one as a letter opener, use a steel more suitable for knifemaking next time (Higher carbon content)

Good luck on your new journey into 'smithing

[MattBower]

Whew! Dude, slow down and read some blueprints. Enthusiasm is wonderful, but by itself it'll end up costing you a lot of unnecessarily wasted time.

There are dozens of approaches to rust bluing, but this is a very effective one:

Black Oxide - Bladesmith's Forum Board

The thing I particularly like about that method is that it doesn't involve really nasty chemicals such as nitric acid -- unlike many, many rust bluing recipes.

[Iron Bear]

Matt, thank you for your kind advice. I'll have to say that my first foray into knife-making actually went pretty well considering I just dived right in. I find a lot of things that have to do with art or crafting intuitive, but you're right - I should research more for safety's sake and for better results/time. I tried following that link by both clicking and by search engine and it wouldn't let me follow it for some reason. Something about "server connection interrupted - page error". As it stands at the moment I have a beautiful finish on it at the moment. After I found I couldn't blue it using the method I had in mind, I had decided to just finish the darn thing. I heated the blade to a brownish color up to the edge before coating it with hydraulic jack oil, then heated again after it was on. The oil film coated beautifully, making a nice slate color on the blade. I put the handle on and gave it a final touch-up and now all I have to do is stain and finish the handle. It was a good starting project, and if I somehow learned something wrong with this project I have plenty of time to do my homework before the next one. I'm going to try searching "black oxide" on a forum aside from the one you mentioned and see if another forum will let me view it.

[MattBower]

What you have there is a baked-on oil finish, very much like the seasoning in a cast iron pan. It can work fairly well, but it isn't as durable as the finish I was trying to point you toward.

The reason the link won't work is that the whole forum is down. Here's the Google cache:

Black Oxide - Bladesmith's Forum Board

Look at posts 9 and 11 by Brian Van Speybroeck.

[MattBower]

Oh, for Pete's sake! Now the Google cache won't work? This is getting ridiculous. Here's what I was trying to link to:

Over the years I have tried virtually every method I could find about making steel black. I have tried all the commercially available cold and hot blues, hot salt, and various recipes for black oxide. The black oxide routine where they mix chemicals and heat the parts works very well but is very poisonous and requires a lot of special equipment. Most of the quick and easy steel black looks great for a bit and then is easily rubbed off by repeated handling. Much of it is like anodizing on titanium...it looks great till you use the knife or carry the piece. Then it ends up polished off in short order.

I do really like the peroxide/salt routine as it is seems pretty safe, uses stuff available locally (and cheaply) and can be done in the kitchen.

*BuT* the rust and boil routine is not fast..it takes a lot of cycles to build up a sufficient depth of rust and get deep and complete coverage. It's not a 1 hour cure all and it takes a lot of time and hand finishing to get it to work. You have to experiment and surface texture before rusting is important as is sealing afterwards. Presently I use the total immersion method and card the rust off after each cycle with a toothbrush and kitchen cleanser...Comet or Bar Keeprs Friend. It takes a lot of cycles to build up thick red rust and I'll usually stop and boil the piece being patinated a couple times during the rust layer build up phase. The difference between trying to do this in an hour and spending an entire afternoon at it cannot be overstated. Repeated cycles of rusting/boiling/rusting/boiling over a period of hours and then sealing the final black oxide with Renaissance Wax or a premium protection oil with rust inhibitors gives the most durable and natural effects of any method I have tried.

I'm a big fan of Break-Free CLP and even fittings I did years ago that are handled very often and used hard have maintained their black rust patina with a minimum of maintenance. I do rub them after each use with a patch saturated in Break-Free but other than that they keep their color when all other finishes have been long ago rubbed off.

Someday when I get back to making cutlery on a regular basis again I'll exploit this rust blackening in grooves and piercings on blades and fittings. Used in combination with commercial blues and browning it has the potential to give some really earthy and exotic looks to fittings and blades.

Brian

The solution I use is 3% hydrogen peroxide and table salt. I mix salt in the peroxide in a glass jar and add salt and heat it in the microwave until it is near boiling...stir and add more salt. Continue until the peroxide will hold no more salt.

I pour the *very* hot solution into a microwave safe (heat resistant) plastic bowl that has the steel fittings in it and let it fizz and boil and fume until the reaction stops. Pull the part, flush the solution down the drain, reheat the solution in the glass jar to near boiling and while that's happening I use a tooth brush and some abrasive cleaner like Bar Keepers Friend and scrub all the loose rust off the fitting and rinse under hot water. Put the part in the plastic bowl and pour more hot solution over it. About every 4 or 5 cycles of rusting I boil the part (after scrubbing) to get black and then more rust cycles.

If I do 15 - 30 cycles the piece is so rusted you can't scrub the rust off no matter how hard you try. Some steels get real blotchy and you have to keep rusting and scrubbing until it is all uniformly rusted. It is not fast or easy. Takes hours sometimes to get it all rusted..sometimes it takes 30 cycles over 2 days. Some steels (some alloys...) just don't wanna rust very evenly.

Then I use Break-Free CLP on the fitting still hot from the boil. Age the part a few days and reoil at intervals. Some pieces wanna produce a fine black powder and will continue to rust and corrode....scrub and boil again and reoil till they are stable.

This is the final evolution of the process I have been using. Oh yeah, I rust over a very deeply etched finish and I etch with ferric to get a deep, crystaline surface before rusting.

Good luck.

Brian

[Bentiron1946]

Iron Bear, Sounds like your having a great time. Keep on having fun.:cool:

Edited November 19, 2009 by Bentiron1946

[Iron Bear]

TYVM for the link, Matt. I was looking forward to the info that you had to pass on. I will try that method and post the results as soon as I gather the ingredients and I have a project I need a rust-proof finish on. Ty, again.

And I am having fun, Bentiron! I am now 5 projects into my list of Christmas presents to make, and I have made a few more tools as well. I have found invaluable help from other blacksmiths, articles, and books. I have also found some great bargains! Picked up a 18" European style tongs at an antique store for only $10, which I can now use as templates to make more tongs. I am having such a blast and the work is such a great outlet for excess energy and creativity. Even my wife is getting into the spirit and coming up with ideas of projects I can make. I love blacksmithing!