Don't really know, there are folks here who do I am sure, but I never wanted to take the chance of buggering up the powder. That said, I got 99.8% pure sulfur, 10 pounds for $6 at a local chemical company, ahh for my fruit trees. They also sell the same stuff at commercial ag centers. Every square inch of dirt in this county is covered with grape vines so we have a good number of places to buy most any agriculture based chemicals.