Cutting

Dividing (medicinal materials) with a knife into two or more pieces. Cutting is a commonly used basic method of medicinal processing. It facilitates drying and storage, increases weighing accuracy, and makes it easier for active constituents to be extracted during preparation processes such as decoction. Cutting is often facilitated by soaking or steeping. Kitchen knives, herb knives, guillotines, and nowadays, cutting machines, are used to cut materials into lumps, slices of various sizes, usually known as decocting pieces. Herb cutters save labor time, but cut less cleanly than an experienced hand cutter using a sharp knife.

Cutting includes cross-cutting (横切 héng qiē), oblique cutting (斜切 xié qiē), and lengthwise cutting (纵切 zòng qiē).

The length or thickness and shape to which materials are cut depends on the material.

• Roots, rhizomes, stems, vines, and woody materials that are hard in substance are cut into thin slices, i.e., about 0.15 cm, whereas softer, less dense materials are cut into thick slices (about 0.3 cm) slices or in lengths of 1–1.5 cm.
• Materials that are long and thin, such as imperata (Imperatae Rhizoma, 白茅根 bái máo gēn) can be cut into lengths of 1–1.5 cm. Skins and barks, such as phellodendron (Phellodendri Cortex, 黄柏 huáng bǎi), that are hard and thick can be cut into shreds of 0.6 cm.
• Thinner, less dense barks, such as eucommia (Eucommiae Cortex, 杜仲 dù zhòng) are cut into broad strips of 1–1.5 cm.
• Brittle, fragile materials like lycium root bark (Lycii Cortex, 地骨皮 dì gǔ pí) need not be cut.
• Leaves that are thick and flexible, such as pyrrosia (Pyrrosiae Folium, 石韦 shí wéi) are cut into strips of 1–1.5 cm. Thick ones that are brittle after drying, such as mulberry leaf (Mori Folium, 桑叶 sāng yè) and perilla leaf (Perillae Folium, 紫苏叶 zǐ sū yè) are either not cut or are simply rubbed between the hands.
• Whole plants with thin stems are cut into lengths of 1.5 cm; ones with thicker stems are cut into shorter lengths.
• Flowers and small fruits and seeds are generally not cut.
• Large fruits or ones that do not dry easily, such as crataegus (Crataegi Fructus, 山楂 shān zhā) are cut into three or four slices.
• Some pericarps such as trichosanthes rind (Trichosanthis Pericarpium, 栝楼皮 guā lóu pí) are roughly shredded.