When SWIM evaps in a food dehydrator, he notices that the amber waxes tend to reside toward the edge, and that he gets more tan waxes toward the middle. SWIM has tried a mixture of the tan and red with mixed results at high and low doses, but when he tried what was collected specifically of the red, he got weak results at very high doses. SWIM thinks that the red is some sort of inactive or barely active impurity. This is from peruvian, which supposedly doesn't have any significant actives other than mescaline. This is nothing new, as the OP touches on this, as well, but SWIM believes he can confirm it for the most-part.
So far 500mg of tar-balls (likely a mixture of impurities and pure mescaline acetate, evaporated with little or no heat) resulted in an LSD-strength experience for SWIM, whereas 600mg from the same batch resulted in very light effects for SWIM's FOAF. SWIM's done about 400-450mg from the same sort of batch with vastly lighter effects. 550mg from a darker brown mixture of impurities and mescaline of both acetate and carbonate (evapped with some heat) produced significantly stronger effects than the 400-450mg but significantly weaker effects than the 500mg tar-balls for both SWIM and his other FOAF. 550mg for another of SWIM's FOAF's and 600mg for SWIM of a redder yield that was a much darker brown when scraped up produced even weaker effects than the previous. The last trial SWIM had was with 400mg of a brown mixture of carbonate and acetate, which was about as strong as the 400mg tar-balls. SWIM's also noticed that he's definitely been able to confirm the activity of every dose he's tried at 100mg with various types of yields, so they all have some decent amount of activity; some just seem to miss the mark at higher doses.
The only way SWIM can conceive of to solve this issue is try different evaporation techniques from the same method of salting (vinegar, for starters), separate and document yields visually and by weight, basify each separately and in the same manner, salt each separately with HCl, finally clean up and document the results. In SWIM's case, he and his FOAF's would have to bioassay the pure mescaline HCl from about 600mg, working their way down, in order to compare to prior trials with the acetate.
SWIM would rather stick to the nontoxic techniques, but since he's been having trouble with his dosages and has some acetone and HCl on hand, he figures it would be a fairly productive way to spend the Winter. SWIM's had at least two amazing and a few satisfying experiences with mescaline in the past, so he feels the effort would be worthwhile. He's just looking to develop some more sure-fire guidelines for administration, considering that so many have had troubles with it.