Yes, they will. It may make a mess actually. On the otherhand, separating layers is pretty much an elementary skill to learn, it would be generally assumed that one does not have a sloppy separation to begin with!

SWIM's FOAF does not want to know how things could turn out in such a case. If water is present in the xylene/toluene, then the dmt fumarate will be dissolved into it. And since the water will most likely be basified with NaOH, some of the dmt fumarate will be freebased and hide inside the xylene/toluene. Any way one tries to see it, bad separation just asks for unnecessary trouble. Just get only the solvent out, it's easier!

Re to the first question, the STB dmt-fumarate product can be washed with clean acetone, just to remove any residual lipid impurities, and any xylene/toluene.

The purely imaginary method described below does work, but it works really really slow. SWIM's FOAF was able to extract ~100mg freebase alkaloids from 10g of MHRB. This method does not discriminate between the alkaloids that are extracted (j.spice, d., d-Noxide etc etc), this is however a subject of discussion.

The tek:

1) dissolve 5g of citric acid per 100ml acetone

2) take the shredded/powdered bark and cover it with enough citric acid acetone. Incubate in a warm place, gently agitating every so often. After 2-3 hours, filter off the citric-acid saturated acetone extract and set aside (this solution should have acquired the dark reddish colour of MHRB). Repeat 2 more times.

3) saturate acetone with fumaric acid. Acetone can hold ~20mg/ml fumaric acid if let for a day or so to completely dissolve.

4) Add the fumaric acid-saturated acetone in the citric acid-saturated acetone MHRB extract. One cannot put too much.

5) Set it aside and wait for 2-3 days. One should see a yellowish precipitate on the bottom.

NOTE: In step 2 one is making an acetone extraction and at the same time converting the alkaloids their citrate salt. After addition of the fumaric acid-saturated acetone in step 4, there is an interconversion of alkaloid-citrate to alkaloid-fumarate salt, like:

dmt-citrate + fumaric acid <-> dmt-fumarate + citric acid

citric acid has a pKa of 3.13, while fumaric acid's pka is 3.43. Fumaric acid is a weaker acid and thus in the above reaction one should have most of the dmt as a citrate salt and just a tiny amount as a fumarate salt. dmt-fumarate however is totally insoluble in acetone (while dmt-citrate is perfectly soluble), and it precipitates as soon as it forms. The insolubility of dmt-fumarate acts therefore as a "sink" and given time all of the dmt-citrate will eventually convert to dmt-fumarate and precipitate out.

6) wash the precipitated fumarate salts with acetone, then take them out and let them dry.

7) dissolve the alkaloid-fumarate salts in 5ml of tap water, then and then add saturated sodium carbonate to make the solution basic. The alkaloids will be freebased and the solution will become milky. In 3 days they will precipitate out forming nice needle-like crystal in the basic solution. At this stage, one can filter the solution (nasty procedure since the crystals tend to be sticky and waxy) and retrieve any left alkaloids by dissolving them in acetone.

8 ) Let the crystals dry, wash them with acetone (it removes any traces of sodium corbonate which is totally insoluble in acetone), evaporate the acetone and enjoy the product.

For the FOAF of SWIM 30mg were for a good STRONG experience.

Hold this tek back for a bit; SWIM's FOAF is trying a better version that might have much much better results.

But if SWIY wants to try it as it is, better do it witha 10-20g just to get a feeling for it before jumping to bigger amounts.

SWIM's FOAF does not like this tek that much, it does work however, and it needs some improvements.

Is it possible that FASA precipitations directly from xylene MHRB pulls are dropping other inactive alks such as NMT, tryptamine, etc?

looking at ron69's post in the bufo thread of xlogp for NMT it is between DMT N-Oxide and DMT. Could edit: (xylene be pulling NMT and may) this be one of the reasons why oral DMT dosages vary so much?
I guess this isnt FASA specific and could apply to evaped xylene pulls but those usually result in a sticky product not often used for oral doses.

just some rough thoughts that came to mind earlier today as i have had varying experiences using similar fumarate dosages from different xylene pulls and similar MAOI quantities. Though this may be attributed to body chemistry variations also.

disclamer: these speculations may be completly wrong

Not much problem, I guess it depends whether SWIY wants to extract some for hyperspace travelling or whether he wants to extract just for researching new extraction methods and techniques.

But if SWIY wants to do it, do not start with 100s of grams. Tell him to go for 10-20g of a known batch with known yield to see how the tek is working FOR HIM. The reason is that this tek has not been tried by many people, (hardly a couple), so not many people will be able to troubleshoot if problems arise.

But most importantly, the tek has not (yet!) proven to be working nicely for a large group of people. Just as an example, the guy who first did it used lab grade acetone, lab grade fumaric acid, lab grade citric acid etc etc. Not the kind of stuff one can buy from hardware stores. How does SWIY know it is going to work nicely for him?

Well he can find out! As I said, try with 10-20g of bark and see how it goes. It would be very promising to hear back with success!