I've just finished leftovers recovery and want to share my experience.
Main batch was 71 gr of pure white mdma hydrochloride in powder after base extraction. Final yeld was 56 gr, that means 15 gr, 21% of initial weight are in water leftovers.
There are a few ways to recover it, but I'm not aiming to recover all, I'm aiming to recover more or less PURE. So I do recovery in two steps.
1. I move crystallizator with water leftovers to average refrigerator under temperature 4c and keep it for a while. Small crystals appear soon in size about 4x2x1mm. They were taken out and weight checked - 7.0 gr.
2. Rest of leftovers were left at RT for some time till dry weight. Weight checked, and it was exactly 6.95 gr. That looks more or less reasonable, considering some product was evaporated or damaged while heated.
This powder was dissolved in water - acetone solution, prepared in volume proportions 1:10. I add this solution by weight 20 gr of this solution per 10 gr of salt.
I use a hot plate to dissolve it: put a stir bar, and set plate temperature 50c.
All salt dissolves easy and fast. Then it moved to refrigerator. After a while it is taken out and filtered with vacuum.. Yeld is 3.5 gr.
Final yeld of recovery is 10.5 gr of 15.0, or 70%, that me personally consider as very good result, and pretty pure, fits for my own needs - at least it will not spoil next batch with its presence.
Water-acetone leftover still keep around 3.5 gr and can be proceeded in the future, but obviously will be more dirty than mentioned above.
I wouldn't work with it without base extraction, but street vendors in Poland might be more than happy with it. Yeaaahhhh!!