doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Oscar's niter blue

I thought I would share Oscar's method of niter blue. He was kind enough to show me how he did this on more than one occasion because I'm sure he thought I wouldn't remember how to do it otherwise.

Oscar used laboratory grade Potassium Nitrate and a very small amount of Manganese Dioxide in his niter pot and it was hot. You might ask hot is hot and all he ever said to me is "you'll know when its hot enough". I'm only guessing in excess of 700 degrees. I supose I could check the temperature with a lead termometer but I don't trust the accuracy of those gagets much at all.

I don't believe that the niter salts that Brownells sells can get to the temperature needed to get the correct color. The niter blue that I've seen from the Brownells product always has a plum cast to it, meaning it just didn't get hot enough to go through all the color phases.

Anyway here's a picture of a Fox Sterlingworth trigger guard that I did this morning to show what I think is the right color. Its a blue-black color with no plum overtones. I didn't take this to a really high polish because it is a Sterlingworth and probably wouldn't look correct otherwise.

Unless the stuff boils away, how can you not make something hot enough by just adding more heat?

I wonder where I can scrounge up lab grade PNO3 and some MgO2?

How small is a "very small" amount?

Now you have me curious....

Looks perfect by the way.

Brent

Several of Dr Gaddy's formulae are on the DamascusKnowledge site. They were posted on this BBS in 06', and were previously published in DGJ
http://docs.google.com/View?docid=dfg2hmx7_161gfwkqnhj
Are one of these for his nitre blue?

Hi Doug,

I use the same method,..Oscar was gracious enough to share this with me as well

Here is a discussion we had on the subject sometime ago

CJ



http://doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=76119&page=0&fpart=1

hmmm, the thread you posted, CJ, says Oscar used a "dash of aluminum sulfate" and this thread says Oscar used a "very small amount of Magnesium dioxide"

Are there two Oscar forumlae or a misrememberance somewhere?

You see, I have this rifle sight that needs bluing and I have the possibility of obtaining some of the materials - if only I knew what they were.

Brent

From June, 1915 Outer’s Book.

I use Manganese dioxie

CJ

Hi CJ,

I'm happy that Oscar shared his method with you as well. He was very generous with information all you had to was ask and show a willinness to learn. He was, after all, still the "Professor".

I do remember him recomending the Manganese Dioxide although he wasn't firmly convinced that it was entirely needed to do the job. He did say that, as MP posted below, something less than 10% was sufficient.

I'll agree that the temperature is probably in the 800 - 900 degree range. I use a face shield, welders gloves and a long sleeve sweatshirt (not a fun outfit on a 90 degree day). I also do this work in my garage because of how dangerous I believe the process is.

thanks a bunch guys. Now I have to round up the ingredients and clean that old casting pot.

Brent

815F/825F and you'll get the blue black color. I get excellent results with the Brownells Nitre Blue salts at those temps so I don't know what the problem is supposed to be with them, they work fine for me. Plain potassium nitrate will yield the same but it's hard to get anymore in small quantitys. I've never put mang.dioxide in 'cause I never had any. I use my lead themometer to keep a close check on the temp. A little higher temp than the needed 815/825 and you get a grey cast to it,,or at least that's what I get. To redo any parts, strip in a weak cold acid bath then repolish.