Fumaric,acid saturated ipa or possibly ethanol can be added to precipitate mesc fumarate. Water saturated with Fumaric acid can also be used in the same manner as vinegar.

Acetic acid will evap away, extra Fumaric acid must be removed or dealt with.

bnd, you are right that that recipe grossly overtitrates and adds more acid than necessary. One of the benefits of using vinegar is that the excess acid will evaporate. Over titrating in this way usually results in more impurities being present in the final product. I really doubt fumeric is soluble in acetone. ***EDIT sorry i meant limo instead of acetone, in response to your original question.***

i strongly recommend that you make your own acetic acid solution with 5% pure acetic acid(glacial acetic acid).Mix 950ml of water + 50ml of acetic acid and thats it.search in the forum for the goo factor thread, not all vinagars are the same and you might get aditional weight from other acids contained, forming goo ( worst mescaline form ever seen).i made tests evaporating acetic acid solution with out mescaline and everything evaporated.anyway for further purification (getting rid of any limo drops and some oils, alcaloids etc) i perform 1 MEK wash.
its not magic, its volatility.
about the acetic acid solution not separating 100% from limonene, just use a hot water bath for 5-10 minutes (or more if needed).Its better to stir and avoid shaking, that way emulsions will be avoided.
other acids for salting? sure but as i uderstand it always diluted in water.ive done hcl and its ok, some people find it to be better than acetate.but for this psychonaut true acetate rocks.
saludos y buena suerte!

I actually did answer you question. I can be more clear

Yes you can add Fumaric acid to your limo. You must first dissolve it in ipa.

If you add powdered Fumaric acid it will just sink to the bottom.

It evaporates into the air. no more magical than evaporation of any volatile substance.

(still kinda magical though)

FASI hasnt proven to be worthwhile to this cat, it even leaves your dlimo with ipa in it unless you clean your nps, that fucks things up in the future for other dlimo uses, just try the vinegar or hcl dilution

Wash your limo with water several times after retrieving your fumarates and you remove the IPA.

Why has it not proven worthwhile? How long did you let it crystalize?

comprable to hcl it was very mellow, i could have botched it, but i let saltings sit for hours and swirled intermittently, i even slept one, and slept another in the fridge... nothing compared to hcl or just dry skins (WHICH ARE THE BEST FOR HUMANS n CATS TO EAT)