Feature of Murasaki

Photographed in early July. White flowers.

Murasaki (Lithospermum erythrorhizon) is a perennial herb that produces white flowers in June to July. Its roots are harvested around October to November, sun-dried, and referred to as shikon (紫根).
The principal pigment responsible for its purple coloration is shikonin, a naphthoquinone derivative with a characteristic violet hue. This compound has been traditionally used as a natural dye in shikon dye (紫根染), the technique of dyeing with purple root extract.
In addition to its role as a dye, shikonin exhibits antibacterial and anti-inflammatory properties, which have led to its application in traditional folk medicine for the treatment of wounds and illnesses. Even today, shikonin is utilized in topical formulations such as Shiunko ointment (紫雲膏), a traditional salve prepared from purple root extract, commonly used to treat burns and skin conditions.

About Murasaki dyeing

Murasaki (Lithospermum erythrorhizon) is a perennial herb that blooms with white flowers between June and July. Its roots are harvested around October to November, sun-dried, and subsequently referred to as shikon (purple root).
There are several related species, including the Japanese murasaki (L. erythrorhizon, known as “kō-shikon” or hard purple root), Xinjiang zicao (Arnebia euchroma, referred to as “nan-shikon” or soft purple root), and Lithospermum officinale (commonly known as inu-murasaki, or “dog murasaki”).
The dye extracted from the roots of murasaki is counted among Japan’s three great traditional dyes, alongside indigo (ai) and safflower (benibana).
Historically, the purple pigment obtained from shikon was considered so precious that it was designated as the highest-ranking color in the Twelve Level Cap and Rank System (kan’i jūni kai), with deep purple (kōmurasaki) and light purple (awamurasaki) both indicating noble status.
During the Asuka, Nara, and Heian periods, the use of such purple dyes was strictly restricted to the emperor and the aristocracy, and classified as a kinjiki—a forbidden color for the common people. In the Kamakura period, the pigment adorned the armor (ōdoshi) of high-ranking samurai. By the Edo period, hues such as “honmurasaki” (true purple), “Kyōmurasaki” (Kyoto purple), and “Edōmurasaki” (Edo purple) came to symbolize luxury and refinement, remaining prohibitively expensive and aspirational for the general populace.

Method of dyeing

alcohol extraction method

After soaking shikon (dried purple root) in water for approximately one hour, the mixture is filtered through cloth to remove particulate matter. Subsequently, the residue is immersed in an alcohol-based solvent—typically ethanol or methanol—at a 1:1 ratio (by weight) relative to the shikon, and allowed to steep for about 24 hours.
After this initial extraction, the solution is filtered again, and the remaining shikon material may be re-immersed in fresh alcohol. This process can be repeated two to three times to obtain additional dye extract. Since the extracted dye solution is volatile, it should be stored in a hermetically sealed container to prevent evaporation.
The resulting extract is used for dyeing via mordant dyeing techniques, wherein the fabric is pretreated with or exposed to mordants to fix the color.
It is important to note that shikonin, the principal violet chromophore, is thermolabile and may undergo discoloration—typically turning gray—when exposed to elevated temperatures. Therefore, dyeing should be performed in water maintained at temperatures below 60°C to preserve the integrity of the purple hue.

Color deference by mordant