Lightweight materials are suitable for decoction in a cloth bag. Some small, soft, and lightweight Chinese herbs, such as Dodder Seed, Semen Tiglii, Cortex Dictamni, Semen Strychni, Fennel, and Lousewort, tend to float on the water surface during decoction and are difficult to fully cook. As a result, the extraction of effective components is relatively reduced, and it also brings difficulties to filter the medicinal juice. Therefore, it is necessary to use a cloth bag for decoction.
Hairy or impure materials are suitable for decoction in a cloth bag. The back of Loquat Leaf is densely covered with brown hairs, the petiole of Houttuynia cordata is covered with star-shaped hairs, and the leaves are covered with star-shaped scales. Silkworm Sand often contains soil, broken mulberry branches, and leaves. If these herbs are not decocted in a cloth bag, they are prone to mix into the soup, making it difficult to filter completely. After consumption, they can also irritate the throat and gastrointestinal tract, causing adverse effects. For safety reasons, these herbs should be decocted in a cloth bag.
Viscous materials are suitable for decoction in a cloth bag. For example, Olibanum, Shenqu, and Fermented Soybean have a viscous texture, which increases the viscosity of the decoction, reduces its fluidity, and causes difficulties in filtering the medicinal juice. This also leads to the adsorption of medicinal residues and loss of effective components. In addition, the sticky mouthfeel after taking the medicine can easily cause nausea in patients. To avoid these drawbacks, these herbs should be decocted in a cloth bag.
Materials that cause turbidity in the medicinal solution are suitable for decoction in a cloth bag. Generally, mineral and shell-like herbs should be crushed and boiled first to increase their solubility, such as Gypsum and Calcitum. However, these herbs tend to make the soup cloudy, which is not conducive to consumption. Therefore, they should be decocted in a cloth bag.
