Zsuzsi
Rising Star
Hello,
after recently performing my first extraction followed by freeze precipitation, I had *a lot* of trouble with floaters in the solvent: free crystals floating instead of sticking to the sides of the containers. In some jars/pulls, almost all crystals were this way.
I spent quite a while searching the nexus for easy solutions to this, finding a lot of topics on them but with conflicting information: sometimes coffee filters were recommended, other times there were suggested as a terrible idea (with the crystals dissolving in the filter itself). As an aside, the Nexus FAQ item on this subject could be improved.
Anyway, thought I'd post the way I personally ended up dealing with it, and it worked great: just remove the solvent very slowly from the container after removing from the freezer (and of course quickly after doing so); and rotate it while pouring as well. The idea is to spread the crystals as much as possible along the container's surface, while still dripping the solvent slowly into another container. If all goes well, most (>90% - that's conservative - in truth I managed by slowly pouring + rotating to save almost all xtals) of the floaters should stick to the container's walls as you slowly poor/as the solvent moves out. You can ignore the ~10% or less that don't stick and end up being poured - let it dissolve in the other container's warming solvent and use it for future pulls to avoid loss. Of course after doing that, put the freeze precip container against a fan to evap the remaining solvent as usual.
This method worked perfectly; and it will work best with a large container, where you can have a large surface area that is *not* covered in sticking crystals to make the floaters stick as you rotate (also, I mention rotating because I used round jam style jars - not sure how you'd solve the problem with say, a flat dish).
This also brings me to a question: did anyone attempt some experiments to pinpoint the main root cause of floaters ? is it linked to the speed at which temperature of the NPS drops ? to the max temperature it reaches in the freezer ? possibly due to the NPS itself, or the container shape/surface ? More generally, I would specifically like to know what helps the crystals to stick to the walls to try and avoid this in the future. There too, searching the nexus forums has failed to produce a definitive answer.
Thanks in advance !
after recently performing my first extraction followed by freeze precipitation, I had *a lot* of trouble with floaters in the solvent: free crystals floating instead of sticking to the sides of the containers. In some jars/pulls, almost all crystals were this way.
I spent quite a while searching the nexus for easy solutions to this, finding a lot of topics on them but with conflicting information: sometimes coffee filters were recommended, other times there were suggested as a terrible idea (with the crystals dissolving in the filter itself). As an aside, the Nexus FAQ item on this subject could be improved.
Anyway, thought I'd post the way I personally ended up dealing with it, and it worked great: just remove the solvent very slowly from the container after removing from the freezer (and of course quickly after doing so); and rotate it while pouring as well. The idea is to spread the crystals as much as possible along the container's surface, while still dripping the solvent slowly into another container. If all goes well, most (>90% - that's conservative - in truth I managed by slowly pouring + rotating to save almost all xtals) of the floaters should stick to the container's walls as you slowly poor/as the solvent moves out. You can ignore the ~10% or less that don't stick and end up being poured - let it dissolve in the other container's warming solvent and use it for future pulls to avoid loss. Of course after doing that, put the freeze precip container against a fan to evap the remaining solvent as usual.
This method worked perfectly; and it will work best with a large container, where you can have a large surface area that is *not* covered in sticking crystals to make the floaters stick as you rotate (also, I mention rotating because I used round jam style jars - not sure how you'd solve the problem with say, a flat dish).
This also brings me to a question: did anyone attempt some experiments to pinpoint the main root cause of floaters ? is it linked to the speed at which temperature of the NPS drops ? to the max temperature it reaches in the freezer ? possibly due to the NPS itself, or the container shape/surface ? More generally, I would specifically like to know what helps the crystals to stick to the walls to try and avoid this in the future. There too, searching the nexus forums has failed to produce a definitive answer.
Thanks in advance !