when making a rocket engine do you need to use pure kno3(potassium nitrate) or will any stump remover do?

i need max thrust witch is why I'm asking,and if you know of an even more powerful engine mix be it liquid or solid please do tell.

Prfesser8 years ago
Nearly-pure KNO3 is needed. Impure KNO3 can be purified by recrystallization. http://www.nakka-rocketry.net/knpurify.html gives directions as well as lots of safety information.