Bluing question ?

[JOSIAH HANLEY]

i am going to try to nitre blue some small parts told i have to use a 'black iron pot' brownells have them but trying to keep the cost down. or can i use something else?

 

[silverchip]

Steel box made from 12.ga. sheet metal

 

[JOSIAH HANLEY]

thanks for the reply !

 

[highveldt]

You can use stainless steel container. When I nitre blue small screws I use a very small dog/cat stainless steel water container from Walmart or Pet Smart. I use potassium nitrate and heat it to about 875 degrees F. If you have not done nitre bluing before then you need to know about the volcanic eruption you can get from just one drop of water on a screw or some other part when you put it into 800 degree F potassium nitrate. It is important to have a thermometer to get the colors you want. If you want lower colors such a violet or purple lower the temperature.

The rifle toplever and safety slide in this photo was nitre blued using potassium nitrate at 875 degrees F

Good luck, be cautious.

Steve

 

[Tim Wells]

I bought a LEE electric lead melting pot for that very purpose. You can get them in different sizes and the thermometer cost me more than the pot did. The thermometer is crucial to keep your temperature steady and the temp for that beautiful blue is a small range.

The nitre blueing salts are the medium through which the heat does the work, about 625 degrees or so.

 

[rmgreen]

From the perspective of a gunmaker. Niter bluing is drawing the temper of the metal being blued. The function of the part MUST be consider before the beauty of the finish. Most parts which can fit into these small containers are not problematic when niter blued however I have seen over zealous finishers soften parts that should remain hard

 

[JOSIAH HANLEY]

thanks! mostly want to do small screws and grip caps what is the different between what brownells sells and using potassium nitrate

 

[Glenn]

I welded a plate on the bottom of a 14" long by 4" black pipe. I've been using it for many years. No problems

 

[highveldt]

Josiah;

Potassium nitrate is the standard salts (saltpeter) that has been used for centuries by gunmakers to nitre blue screws and so forth. What Brownells sells may or may not be good, I have not tried it.

Steve

 

[silverchip]

Yea, the stuff Brownells sells is what I have and use.It is fine.If I remember, it says 550* for bright blue.

 

[JOSIAH HANLEY]

from what i have been reading the brownells works at lower temps than the straight patassium

 

[dclevinger]

Brownell's salts work at the normal temps but melt at around 300' to help prevent eruptions. It can still pop on you though.
I still use nearly the same process as I did in the video mentioned earlier in the post, just made a couple of minor changes in preheating the parts.

ETA- It is a stainless pot in the video. I don't remember how many quarts but it is large enough to hold 10lbs of salts.

 

[golden forge]

I use Brownell's Oxynate No.7, at 292', it's the temp that they recommend, much over 300' and you can start to get a red or purple hue to your metal. All of the containers that I have are stainless, several came from a restaurant supply, and were cheep.
Brownell's has the instruction books available for download on most of their bluings on line.

 

[Arnaud Van Tilburgh]

Where do one buy the Potassium nitrate or saltpeter right? in the gun shop?
We use potassium tablets to boil in water to clean the cloven diamonds, is it something like that?

arnaud

 

[highveldt]

Arnauld;

Although potassium nitrate is the oxygen part of the composition of Black Powder (old type of gunpowder) along with sulphur and charcoal, one does not find it in a gunshop ordinarily.

Potassium nitrate is used also in the making and curing of some sausages and in the preservation of meats such as cured Italian and American hams.

Here in America one can buy potassium nitrate from fireworks manufactures supply sources. In the past in America you could buy potassium nitrate at your local pharmacy (chemist shop) shop, and you may be able to find some in similar or same shop there in Belgium. The most recent purchase of potassium nitrate I made was via e-Bay.

250 grams is about all one needs of it to nitre blue small parts. Nitre Bluing also referred to as fire bluing and heat bluing is nothing more than the oxidizing of the surface of steel rapidly due to the heating of the potassium nitrate. If a part such as a screw head is not going to be subject to handling and wear, you can fire blue the surface of the screw head with a propane torch--slowly heating it until it reaches the color you want. In fire bluing with a propane torch it is best to allow the heat colors to change very slowly from light yellow up to the blue color you want( I like the violet blue colors favored by English gunmakers) and stop heating the item just before it reaches the color you desire. And it is best not to quench the item in oil as it will darken the color.

Nitre bluing is not bluing with "hot bath" bluing salts such as those salts that gunmaker suppliers sell that are used at 285-295 degrees F---those salts are caustic salts. One can make caustic salts from lye and nitrate of soda fertilizer--but this produces a dark black color that is fine for gunbarrels but not necessarily gun screws and so forth that have been engraved and one wants to make them stand out in appearance on a gun.

Ask one of your gunmaker friends over Liege where he gets his nitre bluing salts.

Kindest Regards;
Steve

 

[Arnaud Van Tilburgh]

Thanks for your generous answer Steve.
Could it work on Titanium as well?

arnaud

 

[highveldt]

Arnauld;

Unlikely

Steve