Place the substance in the mortar, and strike it gently
with direct perpendicular blows of the pestle, until it separates into several pieces, then remove all but a small portion, which bruise gently at first, and rub the pestle round and round the mortar, observing that the circles described by the pestle should gradually decrease in diameter, and then increase again, because by this means every part of the powder is subjected to the process of pulverization.
Some substances require to be prepared in a particular manner before they can be powdered, or to be assisted by adding some other body. For example, camphor powders more easily when a few drops of spirits of wine are added to it; mace, nutmeg and such oily aromatic substances are better for the addition of a little white sugar; resins and gum-resins should be powdered in a cold place, and if they are intended to be dissolved, a little fine well-washed white sand mixed with them assists the process of powdering. Tough roots, like gentian and calumba, should be cut into thin slices; and fibrous roots like ginger, cut slanting, otherwise the powder will be full of small fibres. Vegetable matter, such as peppermint, loosestrife, senna, &c., requires to be dried before it is powdered.
Be careful not to pound too hard in glass, porcelain or Wedgwoodware mortars; they are intended only for substances that pulverize easily, and for the purpose of mixing or incorporating medicines. Never use acids in a marble mortar, and be sure that you do not powder galls or any other astringent
substance in any but a brass mortar.
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Labels: calumba, camphor, gall, gentian, ginger, gum, loosestrife, mace, mortar, nutmeg, peppermint, pestle, powder, powdering, resin, senna, technique, techniques