Black Walnut, Juglans nigra, has been used throughout history in herbal medicine to help with skin problems, intestinal problems, snakebites and open wounds. Today, the hulls are known to be an effective anti-viral and may help with cold sores, athlete’s foot and acne. The tannins in black walnut hulls and leaves also have an astringent quality that helps shrink enlarged pores.
Because of its dark color, the outer hull was used in brown hair dye until the early 1900s. Black walnut powder has been rediscovered as a natural way to temporarily darken hair. It does not add permanent color like chemically-laden commercial hair dyes. The pigments will darken or stain hair for a period of time but will wash out over time. The more frequently you shampoo the faster the color will fade. Adding some black walnut hulls powder to your shampoo will help prolong the color. It is also used to add brown hues to henna dyes.