did you do an evap test on the solvent to see if it leaves residues? im not from USA, but I hear people do use VMP.. I dont know how standardized VM P naphthas are..
What can happen sometimes is that there's a mix of plant oils/dmt oxide, some residual solvent that is trapped in this and not evaporating, also keeping some of the dmt dissolved.. So if you mix it around it, scrape and rescrape a few times giving it time, it might harden up/crystalize.
Otherwise if it doesnt after a day or two and if you want crystals, you can redissolve in small amounts of warm solvent and freeze precipitate it.
another option is to redissolve in a bit of a less toxic solvent (like alcohol or also acetone) and let that evap onto some herbs. This will help getting rid of naphtha traces. Remember to weigh the herbs before and after to know how much product you have
good luck, report back
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