If you grind stems into powder and soak them in strong alcohol for a month then evaporate the alcohol you will have a very potent tar like substance. The fact that stems are used shouldn't make it any less potent than it would be if you used buds because either way you have almost pure thc. The only difference is that you have to use much more stems because of the low thc content. I am planning on trying this when I get a few ounces of stems. Does anyone know if everclear or isopropyl alcohol would leave behind any nasty or unhealthy things when evaporated that shouldn't be smoked?