Do the sc wash before you freeze your naptha. You shouldn't need to do any more than 3 pulls if you maximise the first 2.
I would avoiid the filter too, just pour off the naptha after freezing and let the crystals dry. Keep your naptha for future extractions
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When you rexcrystallise you can keep the dmt and warm naptha uncovered till it reaches room temp and then cover and fridge and then freezer.
Hope this helps.