With all my extractions I have always used a Sodium carbonate wash (as described in Vovin's Tek) and afterwards always done a recrystallization, that way I do believe what I get is as close to pure fluffy white crystals you can get without a proffessional laboratory =) Hope this helps!
The first lesson: Patience
The second lesson: Treat Spice with respect and it will treat you with the same. Treat spice disrespectfully, and it will give you a lesson you will not forget.
The third lesson: Keep your eyes closed.