Washes are simply infusions or decoctions that are used directly on the skin. If you have hurt your skin, an abrasion or sunburn for example, any wash that contains a tannin herb such as oak or acacia or older pine needles and soothing herbs such as mallow or chamomile will facilitate healing immensely - prickly pear (a soothing mucilaginous herb) is immensely good for this.
If you have a skin infection or a wound that you want to keep from becoming infected, use a wash of the applicable herbs from this book. If you don't know what kind of infection it is, use the antibacterial wash described below.
General Antibacterial Wash
Combine the herbs with the water. Cover, bring to boil, and simmer uncovered for 30 minutes. Let cool and strain. Then wash the affected skin liberally with the decoction four times daily.