Salt bluing

ballknives

ballknives

Joined
Jun 19, 2006
Messages
207
I have a bag of bluing salts and really don't know how to use it. How do I melt it and what temps? Does it work on damascus or just plain carbon steel?Will it do anything to stainless? how long does it take to color the steel? Any info appreciated.
 
What does it say on the bag? and yes the bluing salts will work on any combo of carbon steel, damascus or not. Even 1018. One thing you HAVE to find out is if you need to mix water in at a specific ratio. Some salts mix with water. Some do not.

Brownells sells chemicals specifically for bluing stainless, I doubt yours will.

I nitre blue with straight potassium nitrate from Lowes and it melts around 400 or so (I forgot) and starts off with a straw color, but as you get up to 700 the parts turn a deep navy blue. Middle of the road blue is pretty cool. Of course 700 is too high for blades, I use it only on parts. However, your temps are gonna be lower. They blend other stuff in it so the operating temp is not that high so you might not bust temper on blades.

The most simple way to heat the stuff is to put it in a roasting pot, stick the pot on a turkey fryer or the side burner on your grill, and heat it up. I would get a deep fry thermometer to stick in there. Depending on the size of the parts you do not need to melt a gallon at a time. I only cook a quart or so at a time. Since you have no instructions, you have to experiment. I would start dipping as soon as the stuff melts, and watch your temps closely and take notes. Depending on what you are dipping, a stainless mesh basket will hold small stuff, or make wire hooks for whole blades. Make sure you get the whole part submerged, it is impossible to get a perfect finish dipping half and half. Only takes a min or two, I move the parts around to make sure I have all the air bubbles off and such.
 
also depending on your salts temp control is a must...not to hot but hot enough or bad things can happen...but the dempreture differ by product
 
That vid is basically what I do. I forgot to mention that degreasing is TREMENDOUSLY impotrant. Even fingerprints with freshly washed hands will show up. Another knifemaker I know keeps his small parts sitting in acetone and picks em up with degreased needle nose pliers to put em in the basket when he is ready to dip.
 
if you do any testing with the salts, do it outside so you have plenty of ventilation. it puts off some fumes that are bad for you to breathe. there is a member here who blues blades all the time. i cant remember exactly who he is but i'll see if i can find out and let you know.
 
I love this forum. I was looking at blued damascus knives yesterday and wondering how they did it. I'm still a bit curious about whether you etch first and blue second, blue first and etch second, or do a repetitive cycle of etching and bluing and sanding until you get the effect you want.
 
you need to talk to Karl Anderson he is the man to tell you all about it.. real nice guy that is very sharp on it
 
tryppyr said:
I love this forum. I was looking at blued damascus knives yesterday and wondering how they did it. I'm still a bit curious about whether you etch first and blue second, blue first and etch second, or do a repetitive cycle of etching and bluing and sanding until you get the effect you want.
Click to expand...

Etch then blue...
 
Thanks for the replies. If I remember correctly it is nitre salts and the temps were in the 400-450 range. I will have to experment and see what happens.:D
 
Niter bluing is one place a cheap small pottery kiln can come in handy ( they are useless for hardening blades). They show up at flea markets, yard sales, and pawn shops. They can often be had for a small price....especially the ones with no digital control ( which is what you want).

1) Make a carbon steel or iron tube to do the bluing in. Just a cap screwed on a piece of 3-4" black iron pipe and welded tight will work, or you can weld a plate to the bottom of the pipe. It works well if the plate sticks out an inch or two from the pipe to make a sturdy base .
2) Cut a hole in the kiln top, so the tube will stick out the top. If the fit is a bit sloppy, stuff some Kaowool in the joint to keep the heat in. Once the tube is in place and the top closed, there will be no need to open it again, so you can put satanite around the tube to make a good seal.
3) Convert the kiln to run off a cheap PID controller. Place the TC in the salt tank. A Monel or stainless clad TC is perfect for the job.
4) Fill with bluing salts and power up. It is best to program the PID to heat the salt to 200F and then raise the temp to the desired bluing temp.
That's it. Simple Nitre Bluing tank....and it does superb tempering to boot.
If you just want to do tempering in the tank ( and things like marquenching) the tank can be stainless. Use low temperature tempering salts.

(The simplest way to set up the PID is to have the SSR wired to a socket that matches the kiln. You can then plug in the kiln and set its switch to "HI". The PID will turn it on and off as needed. For even more versatility,add a second socket to match a standard 110VAC plug. That way you can also use the PID to control a toaster oven for normal type tempering. Just drill a small hole in the oven's side,stick the TC through the hole, and place the TC under the blade.)


This whole setup can be make for less than $100, much less if your scrounging skills are good.
 
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