Re: Buying KNO3

["James Purchase" <jppurchase at rogers_com>]

Folks looking for a cheap form of KNO3 ought to check with the manufacturer
to ensure that what they are getting is pure KNO3 and to determine what
other possible impurities might be in it. I was just searching on the web
using Google and came across the following:
http://members.aol.com/nonillion/kn-exp.html - its a personal website done
by a guy interested in rocketry (who says this isn't Rocket Science?!?!?!).
He was trying to determine the best grade of KNO3 to use as a propellant in
his rockets.

The brand of "Stump Remover" that he used in his tests was "Wilsons", which
is only available in Canada (and I have a box purchased several years ago).
The guy claims that the material he bought wasn't in the form of white
granules - it appeared to have a coating. This coating was apparently lye
(NaOH), which is a very caustic base.

I don't know how common it is for manufacturers to coat pellets of KNO3 with
lye, but if you're trying to save a few bucks it might be a false economy.

For what its worth, the Wilson brand Stump Remover that I have doesn't
appear to have this coating, and the pellets are identical to the KNO3 that
is sold by Homegrown Hydroponics (of course, it is possible that Homegrown
Hydroponics buys their bulk material from Wilsons).

Perhaps, in the quantities we would use in an aquarium, the possible
presence of something like lye might not make much of a difference, but its
something to be aware of.

I asked the pharmacist at a local Shoppers Drug Mart yesterday about
Saltpeter and explained why I was looking for it. He said they don't
normally carry it in stock, but if I was seriously interested he would check
with several chemical supply houses and order pharmaceutical grade KNO3 for
me. But I bet it would probably be expensive (I didn't ask about the price).

Buyer beware.....

James Purchase
Toronto