low-temperature salt recipies

[Khukuri Monster]

Does anybody have recipies to make low-temperature quenching or drawing salts?

I found a snippet of information somewhere online mentioning a 50/50 mixture of potassium nitrate and sodium nitrate. I would try it out but I'm having trouble finding the sodium nitrate. Is there some way to calculate what the melting point and decomposition point of a mixture of salts is? I don't know much chemistry.

I noticed that some homemade bluing salt mixtures contain ammonium nitrate. This would melt at a low temperature, but the decomposition point of ammonium nitrate is also really low - 410 degrees fahrenheit. To me, it seems like using pure ammonium nitrate for a quenching or tempering salt would be an explosive hazard.

 

[fitzo]

Some bluing salts are water solutions and don't use melts. They are used at lower temps around 212F and decomposition isn't an issue.

Somewhere out there is a curve of "melting point depression" for the mixtures of sodium and potassium nitrate but I wouldn't know where to point you, sorry.

Melted salts are usually referred to as "high temp bluing". Brownells will have lots of information in their tech section online.

 

[R.Duncan]

I don't think I 'd use ammonium nitrate in my salt pot. That is if I had a salt pot to start with. LOL
Ammonium nitrate can be synthesized into exploding with only water and heat so be careful expecially if your mixing other stuff with it.

Here is some good reading on Ammonium Nitrate
Ammonium Nitrate

Ron

 

[Laredo7mm]

According to MIL Spec MIL-S-10699B (which is the one many Heat Bath products reference) low temp salts (Class 1) are as follows:

37-50% Sodium Nitrite (NaN02)
00-10% Sodium Nitrate (NaNO3)
50-60% Potassium Nitrate (KNO3)

and thier temp range is from 325° to 1100°


Hope that helps.