Sciencemadness Discussion Board

Hot salt bluing solution

knight guitars - 17-4-2011 at 14:03

Hi all I'm an amature gunsmith and have recently been given the following formular for a hot salt bath treatment to blue steel gun barrels.

NaOh 1843g
NaNo3 482g
NaNo2 113g
Na3Po4 57g
Distilled water 3800g

The solution is heated to 143c the parts are then immersed in this and boiled for around 30mins.

Now I'm no chemist but surely the NaNo2 will turn to NaNo3 when the solution is heated by removing the O from the distilled water. So I can't see why you dont just add 595g NaNo3 instead?

knight guitars - 9-5-2011 at 16:50

Been doing some small scale tests using my afore mentioned substitution and it seems to work well. Whats the best way to neturalise the salts for disposal?

cyanureeves - 9-5-2011 at 17:47

very interesting. why do you want to discard the salts? are they not of any use for bluing anymore? how or where do you get sodium phosphate and sodium nitrite?

knight guitars - 10-5-2011 at 00:41

I was having terrable problems sourcing NaNO2 which partially led to me coming up with my proposed substitution. Being an amature gunsmith I dont have enough reason for chemical supply companys to supply me at the moment.

The Na3PO4 I bought off ebay http://www.sciencemadness.org/talk/images/smilies/smile.gif

The reason you normally discard the salts is that you use the heat given off by the salts as you heat them to help boost the salts up to 140c. Once there up there you can keep them there with your gas burner. Once they cool down they dont do it again and it leaves a sludgy black mess. Also you spend a fortune trying to heat them.