NaNO3 vs. KNO3

[r1dermon]

traditional black powder is often described as containing potassium nitrate as it's primary oxidizer. however, in blasting, there's a different formula which utilizes sodium nitrate.

 

in my experience, sodium nitrate doesn't produce quite as "fast" a propellant as KNO3. one of the major differences is that sodium nitrate is much more hygroscopic, and is easily fouled by humidity.

 

here's my question. in my field (fireworks), sodium nitrate is regarded as inferior. the only reason it's preferred in blasting, is because it does an acceptable job, but for around half the price. im wondering then, why sodium nitrate is actually preferred for smoke producing mixtures? perusing through some mil-spec devices which are designed to emit smoke, i find that sodium nitrate is preferred for producing these effects. pine buff arsenal cites sodium nitrate as the primary oxidizer in their redesigned smoke grenades, and a plethora of smoke producing pyrotechnic formulas already documented, list sodium nitrate as the oxidizer of choice.

 

can anyone shed some insight into this for me?

[John Cuthber]

Not my field, but my guess is they like it for the same reason the blasters like it; it's cheap.

If it's bit damp it will still make smoke (with a little added steam). It won't be as fast or vigorous- but who cares?