i used to go with sodium carbonate washes but i recently tried baking soda washes and decanting after putting the naphtha solution in the freezer for an hour at a time. so far i've washed and decanted once and there is still gunk falling out of the solution. i guess i'll go ahead and repeat this until there is no more dark fluid collecting at the bottom but does this seem like a viable alternative to multiple sodium carbonate washes?

seems to be working. every hour or so i decant the naphtha away from the sludge collected at the bottom. nice color

no sludge and nice fat crystals forming should be nice and clean after a recrystallization.