Well, I'm no expert on the topic but the following procedure has worked for SWIM with good results (~.9%)

When you get red naphtha put it in the freezer for about 20 minutes. This way the brown stuff will have settled but quite a bit of spice is still in solution. Pour off the clear naphtha into a different container and put back in the freezer. You will get crystals after ~12-24hrs.
The brown sediment in the first jar will still contain some of your goodies so let the rest of the naphtha evaporate from this and wait till it's completely dry (takes about 1.5 days). Then pull (mix well) with IPA or Acetone, filter and let evap.

SWIM has gotten brown naphtha almost every time after the first or second pull. The end product however is lovely and the yield seems alright IMO. Smoke is not harsh, effects are good. Crystals in the cleared up naphtha are white.

Ive only done stbs what is this five minute a/b you speak of? my friend has muriatic acid and would like to use that. anyone have suggestions? my research is just confusing me further i think. so any one to clarify would be just awesome. thanks

my friend has muriatic acid. hes never done an acid to base before. dose he really neeed to simmer it? or will the alkaloids be pulled into the muriatic solution since they are already pulled from the "soup"? help is mnuch appreciated my friend would love to trade his dark brown jars in his living space for some crystals in his drawer. thanks!

Got the same problem today, same tek I alwasy use - powdered bark usually get yellow napatha. Only diff was i had everything sitting in the garage in Texas heat for a day, so id add my vote to the temps being the cause. Gonna try a wash and see what id does casu i got ALOT of brown shit.

Don´t throw away the goo when finished, i had a similar thing happen to me and the seperated goo is preety potent although not pure spice.