you are almost there
The quantity of warm naphtha (around 45 degrees seems fine) is about 25ml per g of impure product you want to clean. One should leave the warm naphtha for a minute or two, swirling around so that the dmt dissolves, and on the bottom, a gunk most likely remains.. Pour off/pippette off the clean naphtha into another container, maybe add another 5ml of naphtha to gunk just to make sure you got all dmt, and then add to the rest. Only then do you put in the freezer.
As for how to retrieve the crystals from the freezer, it depends.. For some people, they take out from freezer, quickly scrape the crystals with the whole naphtha still inside, and then pour naphtha through coffee filter. Three issues that may come with this way is:
-Splashing around of naphtha and crystals while scraping (so dont be too rough)
- a lot of crystals that werent scraped after you poured off the naphtha (in this case, after pouring the naphtha, keep scraping and rubbing these crystals on top of the coffe filter or just on the sides of a plate.
- Crystals melting inside coffee filter (in this case, you will have to use some warm naphtha again to pick it up from the filter.... Using some sort of vacuum contraption to speed the filtering process diminishes the chance of dmt melting in the filter)
Or, one can just pour off all the naphtha, put the container upside down but with some support so that it is at an angle, with space for air to come in. Then put a fan next, blowing air in direction of the container. This way the crystals dry out and any remaining naphtha will drop off/evaporate. Sometimes people get crystals melting, but for SWIM this works...
you're gonna have to see what works for you.. Maybe dont do with all your stash at first, get the technique right and then its not so risky.
Good luck