Swims read powdered bark does not require pre-acidifying, but will the yield be affected much?

The differences just come down to quality. STB may get you slightly more but to get it clean it has to be recrystalised. An a/b results in a slightly smaller yield but it won't have to be recrystalised.

really, i would have never guessed... thought ab would get more alkaloid out. thanks.

If you are using prepowdered I would still acidify...I would NOT do an STB on it.

There is a problem many people are having with STB on prepowdered, you end up with a red contaminant that makes the smoke a lot more harsh and slightly affects the experience. The only fix that I have found for it is to do an A/B miniextraction on the red xtals.

In general STB gives a slightly higher yield UNTIL it has been cleaned up. STB pulls a lot of oils and other crud from mimosa (non-alkaloidal) that you CAN smoke, but it is a very harsh unpleasant smoke. So to say that a STB pulls more alkaloids out is not quite correct. It pulls out more stuff, but not more spice.

When you compare white xtals to white xtals (not the yellow wax from a STB) it's usually a close call, but A/B has always served me well, with less mess. I always worry about a highly caustic jug sitting around my house. Plus with an A/B you use A LOT less lye, which is becoming harder to find and shouldn't be bought in large amounts.

Go with an A/B on prepowdered if just to keep from getting that nasty red contaminant, a splash or two of vinegar per cook should be fine.

Alternatively, PPMHRB is well-suited for limtek extraction. SWIM uses this process with blender-pulverized whole bark and pre-treats with a little vinegar and heat prior to basification with lime, but he has no indication as to whether its necessary as of yet; however, SWIM's accustomed to such preliminary measures, as he used to pre-treat bark with HCl before performing an STB. Some have claimed--and as SWIM's inclined to believe--that acid-treatment reduces emulsions in STB.

SWIM's not certain about the red crystals. His fumarate is quite red and is full-range from MHRB by limtek and FASW, and when converted to freebase by this method, yields a pale yellow clay chunk as pictured in the appendices. SWIM has no problem with harshness using either of these two methods or this method.

Never had a problem doing STB on prepowdered, spice comes out quite white with a hint of yellow. Never once had a red colour either - maybe the type of naptha used to pull causes this?

Is there any other solvemt that pulls this red colour?

SWIM knows that extractions utilizing limonene can turn out red fumarates (FASW certainly does), but red freebase is generally the result of xylene or toluene evaporation, i.e., jungle spice. Some say jungle spice is harsh, but SWIM doesn't find it as such with his methods. SWIM's spice takes on a red color when he melts it.