gun blueing a knife

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Posted (edited) · Report post

index.cfm?fuseaction=user.editAlbumPhotohey yall i finally made my first knife with tools in a woodworking shop, my grandpa suggested blueing it with some gun blue and a propane torch, it worked the first time...sorta we heated it up to much and tried to apply the blue, but it wouldnt take, so we splashed a little water on it and tried again, it gave the knife this beautiful blue sheen but it also had some blueish black smudges that looked like grease residue almost. I got most of it off but i cant figure out how hot to get the blade next time, or how to tell if its hot enough Edited by TexasIronworker

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Posted · Report post

hey yall i finally made my first knife, my grandpa suggested blueing it with some gun blue and a propane torch,.....out how hot to get the blade next time, or how to tell if its hot enough


That certainly is an interesting application of a finish, but possibly shocking to individuals who in the process of making knives are concerned about the knife's heat treatment and ability to hold an edge. You might want to:

1) focus on how to properly heat treat the steel for the blade.
2) at least at this point in your stage of learning about knifemaking, plan on using a cold-blueing process after the blade is heat treated so as to maintain the heat treatment of the blade, or use a more traditional knife finish.

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Posted · Report post

Strip all blueing and start over follooinw the driections on the label They may have a starting poinf for tempperature. Use an over to get the temp they suggest. If no suggestions start at about 150f in an oven,,,, just a guess

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Posted · Report post

If you want a true gun blue finish I think that you can buy bluing salts from Brownells, at least 30 years ago you could, so you may want to Google "bluing salts" to see who sells them now. Hot bluing is usually done in tanks of boiling caustic salts that slowly turn the steel blue. It has been a while since I have hot blued anything but the most we ever did with anything that came in a bottle was warm it up with a heat gun to just about the level of "uncomfortable" to hold and then apply the cold bluing solution. I suggest you read the directions again.

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Posted · Report post

That certainly is an interesting application of a finish, but possibly shocking to individuals who in the process of making knives are concerned about the knife's heat treatment and ability to hold an edge. You might want to:

1) focus on how to properly heat treat the steel for the blade.
2) at least at this point in your stage of learning about knifemaking, plan on using a cold-blueing process after the blade is heat treated so as to maintain the heat treatment of the blade, or use a more traditional knife finish.


we heated it to red so about 1000degrees and quenched it in motor oil, when we blued it it never changed color. would that have affected the temper

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Posted · Report post

we heated it to red so about 1000degrees and quenched it in motor oil, when we blued it it never changed color. would that have affected the temper


As I am sure you read the knife sticky's on heat treatments, you know that 1000F is fine if you used H13, you did use that correct? :o

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Posted · Report post

no sir i did not, i had no clue what that was, it was a project me and my grandpa did in his woodworking shop with tools we had on hand and i believe i misspoke earlier, what i meant to say is that when we heated the blade in order to blue it, the steel never changed colors.

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Posted · Report post

By "did not change colors", you mean it never got "red hot", right?

Thing is, if you had it polished bright when you hit it with the torch, you would have seen oxidation colors run thru the steel... straw, bronze, purple-ish, blue, etc. This would have shown you the temper of a particular steel. Depending on the steel, if you exceded 450 degrees, you might have "lost your temper"... blade too soft. More in some; less in others. Also, 1000 degrees might not be enough to get full hardening in most steels.

Seriously, read all you can first. There is a ton of information here to address your problems. I promise it will all make a lot more sense.

If you're set on a blued blade, a lot of these guys use cold-blue on knives. You might look into that.

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Everyone else has commented on the judicious application of heat so all I will add is that Brownell's sells two good cold blues - one is Oxpho and the other is Dicropan. The Oxpho is a very good product and works well to cold blue a carbon steel knife (without applying heat)

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Posted · Report post

Whenever I have a plating question I always go ask caswell plating. I've used their kits before with good success. They are the go-to guys with home plating, bluing, oxidizing, etc. Smart bunch of guys over there.

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I've seen a good many damascus art knives hot blued, but from what I understand the temps used to blue causes a little edge holding loss. Not sure how much exactly.

I've used Birchwood Casey super blue and like it for some damascus, realy improves the contrast, and no heat.

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Posted (edited) · Report post

I've seen a good many damascus art knives hot blued, but from what I understand the temps used to blue causes a little edge holding loss. Not sure how much exactly.

I've used Birchwood Casey super blue and like it for some damascus, realy improves the contrast, and no heat.


The hot bluing causes absolutely no edge holding loss.
Oxynate 7 hot bluing is done at 292 degress. Only 80 degrees more than boiling water.

15944.attach

Edited by mod07

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Posted · Report post

Very nice work! Last time I looked into hot blueing it was in the 400+ deg. range, under 300 deg. would be perfect.

Thanks

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Posted (edited) · Report post

I haven't used it yet, but a friend just sent me some Blue Wonder gun black. Their website is Bluing and Protection. I can't vouch for how good it is. I haven't checked out their site yet either. I just saw this thread and thought I'd see if I could learn a thing or two before I applied this stuff to my blade. Maybe this stuff can help you out.

Edited by mod07

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Posted · Report post

What does damascus look like that has been blackened? Is the contrast more severe?

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Posted · Report post

i think that a blued blade is very cool have you ever considered cold blueing
although it personaly think blacking is the better option try haveing a look for a book called the blueing and blacking of gun barrels it has recipes for some cold blue methods

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Posted · Report post

Here's one I did a while back.

16100.attach

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Posted · Report post

a better pic

16101.attach

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Posted · Report post

Will, that knife's kind of ugly, maybe you should send it to me to purty it up... All kidding aside, that's really, really nice mosaic work man. Also love the leather spacers with antler. Really classy looking blade man.

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Posted · Report post

Its not ugly but It sure belongs in my trash barrel. Can you get it here just after noon
tommorrow. they pick up about noon. I am not a knife person but that is my kinda knife.
Ken

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Posted · Report post

Thanks, it's been sold for a while now though. With normal damascus, especialy the higher layer stuff I don't blue, but with mosaics I like to blue sometimes due to the large low number of layers. May experiment some more when I get my shop done.

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Posted · Report post

A couple of observations.

You heated and quenched the blade, but you don't mention tempering it. If not, the blade may be too brittle to use. I have made quick general use knives out of files. After heating and quenching I polished the blade, and then reheated until I saw a dark straw to purple color. When I did I requenched the blade.

Oxpho bluing works good as a cold blue, but it grabs better if you heat the item up some first. Usually just hot enough to where you cannot hold it-NO COLOR CHANGE. When you apply the blue keep putting enough of it on so the blade stays wet. This is what we did in the gunsmith shop I worked in. Another thing that helps the blue to last longer is do not use a power buffer, hand sand the final polish. Power buffers can smear the metal and seal off a lot of the surface pores, not allowing the blue to penetrate. Hand sanding cuts the surface leaving the pores open. 230-320 grit is fine for a final polish when bluing.

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