It always seemed pretty confusing to me as well, until I actually did it. And the STB teks are pretty easy (this is a simplified version, follow the teks to do it right)
1)add lye to water,
2)add bark to water,
3)add naphtha (or some other solvent) to the mix,
4)pull naphtha(solvent) out,
5a)evaporate naphta
OR
5b)stick naphtha in freezer and collect the crystals that form, and reuse naphtha.
Then when you move to an A/B tek it is almost just as easy (once again, this is an over simplified version, follow the teks to do it right)
1)add bark to water,
2)acidify water,
3)strain out bark, save the water,
4)basify saved water
5)add naphtha (or some other solvent) to the mix,
6)pull naphtha(solvent) out,
7a)evaporate naphta
OR
7b)stick naphtha in freezer and collect the crystals that form, and reuse naphtha.
You can do some defat/washing steps as well to get a cleaner final product, these are explained in the various teks.
“Surrender is inner acceptance of what is without any reservations. If you have lived long enough, you will know that things “go wrong” quite often. It is precisely at those times that surrender needs to be practiced if you want to eliminate pain and sorrow from your life.”
Eckhart Tolle