The Herbal Medicine-Maker's Handbook_ A Home Manual - James Green [172]
PRECIPITATION
Precipitation is the formation of solid particles in a previously clear solution. At times in pharmacy this is promoted intentionally, usually to “purify” a product. However in our humble work, precipitation and its formation of precipitates is ordinarily unintentional, unsightly, and not welcome; so we attempt to avoid it. For the purpose of appearance, it is usually easier to prevent disagreeable precipitates or other offensive appearances than it is to remedy them.
Therefore, if a resinous tincture is to be mixed with water, it is best that the water be cold and the tincture slowly added to it in a fine stream while stirring; never do the reverse by pouring the water into the resinous tincture. By following this procedure, the resinous particulates are still precipitated, but they are formed in such fine condition that they are easily diffused by shaking the mixture.
When you attempt to mix a strong (high percent alcohol that is high in alcohol-soluble components) with a weaker alcoholic extract (and maybe then water), the strongly alcoholic liquid should be gradually diluted with the weaker (and the water added last). Less precipitation occurs using this procedure.
PRESSING (ALSO REFERRED TO AS EXPRESSION)
Pressing is a process for separating liquids from solids which involves the use of some force. This is because pressing is employed in those cases where the amount of liquid is small compared to the quantity of solid matter that is to be removed. Pressing is employed to extract juices and oils from various fruits, nuts, and vegetables, from some fresh herbs and grasses (see “Succus” below), and the expression of herbal solutions from their marc.
There are many devices appearing on the market today that have been designed for the herbalist to press his or her marc. Some of these devices work reasonably well; some don’t. The renewed demand for tincture presses has in the past ten years been significant, and those engineers and machinists who are attempting to service this request have marketed their first prototypes. I deeply appreciate their efforts and have used a variety of these presses for a number of years. However it is obvious to me that significant modifications need to be incorporated in future product designs, the most salient starting place being the steel container which holds the material to be pressed; make it cylindrical rather than rectangular, please! And let me know when you have one for sale (see illustration of an old single-screw tincture press).
Hand Wringing
Potato Masher
Single-Screw Press
Hydraulic Press
When using a device like the hydraulic press or the screw-press, the substance to be pressed is first put into a canvas bag, or a cotton muslin cloth that has been wrapped tightly around the wet marc much like a burrito. As pressure is exerted on the herbal burrito, the pressure forces the liquid between the meshes of the cloth, and the marc is detained within. Unless, of course, the cloth bursts. This all too commonly occurring perplexity can be kept under some measure of control by applying the pressure slowly, giving the liquid time to exit gracefully through the cloth housing, and by using press cloths that are relatively fresh. If you insist on using one that is obviously battle worn, you’re asking for the often ornery combination of marc and menstruum to extemporarily express itself as extended cleanup time.
The potato masher (purchasable in antiques and collectibles stores) is useful for expressing small parcels of marc; use it as you do a garlic press, and the hand-wrung process is performed as illustrated.
RULES (PROPOSED) OF MEDICINE-MAKING
As a teacher who values the creative potential of students more than the content of my teaching, I seldom express any rules of the art and science in discussion. I feel it is wise and important for a student to learn basic theory