View Full Version : NitreBlue hot blue from Brownells

Wolf Lies Down
October 2, 2007, 03:01 PM
-Does anyone have any experience using this NitreBlue hot blue? It is supposed to deliver a "Fire Blue" finish. Is this stuff any good and does it deliver a better finish than the cold bluing solutions?

If it delivers good results, I think it might be a very good and portable alternative to a full-blown hot-tank bluing setup. I would like to get some feedback from any of you folks who may have tried the NitreBlue Brownells.

I called Brownells and spoke to one their technicians regarding this stuff. He says that it's pretty easy to use, so I gathered some info and put a pencil to it. Here's what he said and what I derived:

--- prepare the gun parts as directed prior to immersing in the hot salt.

--- get a natural gas or propane gas burner going outdoors. I just assume (yikes!) that you already have, can borrow, steal, or can inventively pull a burner setup out of your butthole.

--- heat up the bluing compound (don't use an aluminum or copper container) to about 650 degrees F. The NitreBlue salts will melt. Once the stuff comes to the right temp, dip the parts in until the desired color is attained. Remove the parts and proceed as directed with the parts.

--- The NitreBlue salts cost 10lbs=$40 and 20lbs=$62. plus a separate HazMat surcharge (God know what that costs). I understand the NiteBlue is reusable and sets up into a chunk as it cools. NOTE: I don't know, but I hazard a guess here that storing these salts is something you want to be careful about so that they are in a container that will itself not corrode and that is airtight so that the salts will not corrode or damage stuff around where the salts container is stored.

---You'll need a thermometer and Brownells has a heat-treat thermometer with a nice range of 200-1000 degrees F, for a mere $40.00. NOTE: For best accuracy, your thermometer should have a range where your operating temperature falls pretty much in the middle of the thermometer's range.

--- The Brownells tech said the Brownells quarter tank or something like it is good to heat the salts in. The quarter tank is a container that is: 1 gal. capacity, black iron, 6"x6"x10" for a paltry $35.00 Larger, longer tanks from Brownells cost $50.00.

--- So, I figure the cost to do this NitreBlue finish, minus the cost of a heat source, but including the basic chemicals and hardware, along with all the extra stuff you MUST have, such as face shield, dippers, tongs, corn chips, wire, hooks, magic wand, gloves, apron, beer, etc. is approximately $250.00 or so.

If it works well, and if the salts really are reusable, NitreBlue might be a worthwhile investment for the non-professional gunsmith.

BUT....do any of you have any experience with this stuff???

October 2, 2007, 04:07 PM
Just about ANY hot blue is better than cold blue.
You forget some other tanks for rinsing and cleaning, and bluing salts are VERY corrosive to any ferrous metal near the tank (let alone aluminum like ductwork).
The normal burner is a pipe type affair to match the shape of the tank.

Disposing of used bluing salts is also an issue.
For occasional use find someone you like and trust that blues full time and have them do the work.
Most of the labor is the preparation, not the actual bluing step.

George R
October 2, 2007, 04:40 PM
I use nitre blue all the time, but only for small parts. I believe the high heat is not good for frames or slides, and don't know anyone who does whole guns. It's hydroscopic, I think that's the right term, it attracts moisture, so I have to be real careful to cover the salts after I use them. Water at 600 degrees is not nice. Also, nitre blue is nowhere as durable as real hot caustic blue,--- but it sure is pretty. I use used stainless steel tanks from a restaurant supply house. Available in handgun sizes. And cheap!

James K
October 2, 2007, 09:08 PM
"...it might be a very good and portable alternative to a full-blown hot-tank bluing setup"

Alternative? Sounds a lot like a tank blue to me. Looking at Brownell's catalog, it seems like the setup and work is little different than a standard hot tank blue, except that only one tank is used. The chemicals are just as dangerous and the same precautions necessary. (And with only one tank, degreasing and cleanup becomes a lot harder.)

Also, it is too hot for anything but what Brownell's calls "small non-critical components" like buttplates, grip caps, and sights, "to avoid changing any heat treating on action parts."

In other words, it provides a colorful (but not very long lasting) blue for decorative purposes on gun parts that are not heat treated.

It would be useful for custom gun makers, but you couldn't use it on a whole gun. IMHO, it seems like a lot of work for little practical use.


George R
October 3, 2007, 09:07 AM
There is no need for a cleaning or degreasing tank. This stuff is so hot (550-600 degrees) that it just burns off any residue, oil etc. I don''t think it would be easy to get a 40" tank to the temperature needed. And Jim is 100% right, it isn't durable enough for a whole gun. Luger parts straw and nitre, Mauser ejector springs, accent parts are just beautiful, but not the whole gun.

James K
October 3, 2007, 03:06 PM
I should have noted that nitre blue was used AS PART OF the heat treatment process on guns like the Luger. When you reheat those parts, the effect of the heat treatment is lost and the parts become soft even if the color is "restored."


George R
October 4, 2007, 04:02 PM
Jim, I'm confused. If the last thing they did to the original part was to heat it to straw color and 70 years later I polish it and reheat it to straw color, why does it get "soft"? I'm certainly no metalurgest, I can't even spell it, but I've straw and nitered a lot of springs and never had one loose its tension. Ever.
You're probably right, you usually are, but I'm interested in why you say this happens.

Bill DeShivs
October 4, 2007, 04:37 PM
As long as the original coloring temperature is not exceeded, heat treatment will not be affected.

James K
October 4, 2007, 10:21 PM
The "original coloring temperature" will vary depending on the exact composition of the steel. If I don't know what that is, and don't know what the original temperature was, do I know that it is not exceeded?

I would prefer not to take chances on guns that will be used; for show guns, it may not matter.

Also, the heat treatment of the part depends not only on the heat temperature but on the treatment after it was quenched and drawn. The color comes at the latter point, not during the first heating. If the part is reheated, then not quenched and drawn properly (again as determined by steel type), the part can become either brittle or soft.

I have known quite a few gunsmiths who did "nitre bluing" with a torch to get that bright blue or straw color. It usually works. When it doesn't, a possibly irreplaceable part is ruined.


George R
October 5, 2007, 03:48 PM
Thank you for the information.

Wolf Lies Down
October 6, 2007, 09:19 PM
Thanks everyone for the information regarding the NitreBlue.

When I said "portable", I meant portable in the sense that NitreBlue seems (or rather, seemed) to be a "one-shot" solution compared to all the tanks and stuff I think are necessary for a multi-tank hot blue operation. NitreBlue seemed to me to be something you could set up quickly, do your work and shut down and store fairly quickly and easily while being able to recover the NitreBlue material and store it for later use.

I DID think the 600 to 650 degree F operating temperature might be a problem, but I was not sure.

So, once again, thanks for the input and explanations.

Wolf Lies Down

October 7, 2007, 08:57 PM
I have done a little nitre bluing, with a very simple set up. I used an ex pet's stainless steel water dish, and a burner on the top of the stove.

Any potassium nitrate will work. I have even heard of people using the stump remover stuff.

It is only useful for small parts, and the temperature does get high enough to wreck the temper.

I have waxed the parts that I have done, and they wear reasonably well.

Warning! Salt peter at this temperature runs like water. It is, however, hotter than the lead we cast bullets from. Use appropriate care.