Hot Bluing

[indian george]

I have a hot bluing tank, but it is to large and takes to long to get up to temp, just to do a small piece. Has anyone tried use a cast iron pan for a tank???.

 

[ragnoor]

What type blueing salts are you trying to use, low or high temp ?? I do not think it makes any difference with what the salts are put in, as long as they will handle the temp required for the salts, scanna.

Ken Beatty

 

[Dan Gray]

Ig get a small ss cooking pot, with
cast your going to get crap from it.

edited for spelling

 

[Mike Hull]

George, IIRC, hot bluing tanks are usually stainless steel, as anything else gets eaten up. The stuff is pretty caustic.

Another thing, anything else metal in the room where the hot blue is being done, will rust, badly.

 

[indian george]

In the instruction it said not to use any SS because it contaminates the salts. I got the tanks and salts from Brownell's. They work great. The tanks is just plain steel.
I do all the bluing in my smitty and store the tank outside.
Thanks Ken cagon

 

[Dan Gray]

IG Lamont's and my salts are Brownell's Niter blue
and using SS to melt in
you've seen his bluing

 

[indian george]

Dan; How long have you had them in the SS?? Is the boiling point at 292deg. ?

 

[Chuck Gedraitis Knives]

There are 2 kinds of hot bluing, one is nitre bluing and the other is hot bluing. Both use salts and both have to be heated.

The one you have IG is meant to stay in the plain steel tank. With that one you can only get blue color, and the salts tend to migrate out of the tank (grow) and make a mess sometimes.

With the Nitre bluing salts you also use heat, but depending on the temp you can get a variety of colors. The composition of the steel can also give you different colors. 475 deg will give you a bronze color and 550-600 deg will give you blue. When it cools it turns back into a solid and does not migrate. You can also melt it in a small stainless bread pan or other small stainless container for small parts. It also heats in a very short anount of time. I think you also need water displacing oil as part of the bluing process, either before or after you blue. Everything can be bought through brownells.

 

[Danbo]

Now that somebody mentioned the temps involved in these blueing processes, maybe somebody can explain to me how knifemakers are blueing blades without damaging the heat treat of the blade itself? I mean, I see carbon steel damascus blades being blue/purple/gold colors, and cannot help but think these makers have given up on the blade ever being used.

 

[Chuck Gedraitis Knives]

These makers are only submersing their blades into the solutions for a few seconds, up to 30 at the most so it dosen't affect the temper.

 

[ragnoor]

Jantz supply sells a low temp blueing salt, 270*F. It will not effect the HT of the blade.

Ken Beatty

 

[Bruce Bump]

I have two types of bluing salts both from Brownells. The Nitre Blue is a solid brick and melts. It can be used in SS pans with good success. The general bluing instructions say not to do that though as it will reduce the effectivness of the bluing. Nitre Blue needs to be about 600 deg. and will give a wide variety of colors but I dont think the colors are very permanent. Citric acid can take it off. Most people use it for art knives. I think it will harm a good HT.

I like the Oxynate #7 that I think IG is using. It boils at 292 deg. if it is mixed correctly. It needs constant attention and is a pain in the butt to store. The good thing is it leaves a very deep gun blue color and wears very well. Several professional gun bluers use it for guns and gun parts. It requires a room of its own with massive ventaltion. I do mine outside. Really corrosive stuff and not very enviromentally friendly. When it wears out you have to buy the high priced kit to neutralize it and dispose of it in a hazardous waste facility. I blue almost everything with it. With a multi steel damascus it will give some pretty colors like greens, dark blues and red tones and silvers if pure nickel is in the mix. It needs an iron or mild steel pan and can be mixed in small quanities for small parts. With the low boiling point (292 deg) it cant harm any heat treatment and can be left in for 30 minutes. It also doesnt affect gold or silver inlays or plating. It will melt soft solder but not silver solders.

 

[indian george]

Thanks Bruce, I am using Oxynate #7. The stuff is nasty. I bet it would work good for killing skunks.

 

[Bruce Bump]

You may be onto something big George. That smell may be the missing link to better blue colors! :barf: