I've noticed that when I take some finished spice, disolve it in either naphtha or heptane, there winds up being very little of it present after 12-16 hours of freezing.

Others have noticed that they can leave the solvent sitting around for days, weeks or months and DMT eventually precipitates.

It doesn't seem to be a problem on the original extraction, only redissolving into solvent. It also seems to be a problem when instead of disolving in solvent, I disolve in acidic water for a mini A/B.

Does anyone have any thoughts on this and how to speed up the precipitation?

If you were to reduce the volume of naphtha that you're freezing (by letting half of it evaporate), you would probably have more spice precipitate out of the naphtha

The only things I know of for speeding it up are using minimal solvent and colder temperatures.
If you (carefully!) warm your solvent first you can get away with using even less of it. Add just enough to dissolve the spice. If done correctly you can see some fall out just by leaving it to cool at room temp.
And for getting a colder temperature you could check your freezer for a temperature setting if you haven't before. I actually just found one on mine the other day =)
Also try not to disturb it once it is in the freezer.

Like Frobot said, just use a very small amount to re-x. We're talking VERY little here. To re-x I don't use anymore than about 15-20ml per gram of spice, this means if you have 100mg then that 1.5-2ml of warm naphtha. Put spice in shot glass, dissolve with said amount of naphtha. Once it's dissolved the spice there will be some other stuff in the bottom of the shot glass. Then you can decant your dissolved spice into another shot glass. What I like to do at this point is the slow evap method rather than freeze precip, this creates much bigger xtals! Just cover the shot glass but leave a small gap and put it out of the way to slowly evaporate. Best way IMO!

Peace

Fornunately I have little food and was able to see the temperature adustment ;-)
I moved the freezer further from the wall, cleaned the coils and keep a fan blowing behind it, 13 degrees C.

Thank you PHOman, frobot and Twenny'.