Seal up the jar or bottle and leave for two weeks. Be sure to shake the jar or bottle thoroughly once or twice every day. Strain mixture before using. A poultice is most easily made by mixing dried powdered herbs, which may be crushed by mortar and pestle or purchased powdered, with water to form a paste. This paste is then spread over the affected area with direct contact to the skin.
Some stronger herbs can cause dermatitis or skin irritation when placed on the skin.
In this case and with open or festering infections, it is best to use a plaster. Herbs for a plaster are prepared in the same way as for a poultice, the only difference is that one or more layers of muslin, linen, cheesecloth or some other cloth are placed over the skin. The herbal paste is then spread over the cloth. A compress is simply a towel soaked in an herbal infusion, then placed on or wrapped around the affected area while still hot. Compresses may be replaced as they cool and, for this reason, it may be easiest to use two towels and keep one warm while the other is in use.