Aigami

Aigami (藍紙), literally “indigo paper,” is the Edo-period Japanese pigment prepared from the petals of the Asiatic dayflower, Commelina communis. The plant grows wild across most of Japan and East Asia, flowering for a single day at a time with small, deeply pigmented blue petals; Edo-period dye-houses harvested and crushed the petals at scale through the summer months, expressing the juice and absorbing it onto strips of paper for storage. The dyed paper was then soaked in water at the printmaker’s bench to release the pigment for use. The colour-bearing molecule is commelinin, a metalloanthocyanin in which six anthocyanin molecules (malonylawobanin) and six flavone molecules (flavocommelin) are bound together by four magnesium ions, producing a deep saturated blue absorption that fades reliably under daylight and degrades on contact with mild acid.

The pigment was the standard blue of early ukiyo-e woodblock printing through most of the eighteenth century. Conservation analysis has confirmed dayflower blue in Hokusai prints from around 1800-05, and the colorant is consistent with the period palette of ukiyo-e masters including Utamaro and Sharaku, though pigment-analysis confirmation for specific named works by those artists awaits further technical study. The colour would have been intensely saturated when freshly printed, and the early prints very likely read as far more blue than the surviving examples in modern collections suggest.

The defect is severe. Aigami is essentially fugitive: highly sensitive to light, with visible fading after only a few years of display. Surviving early ukiyo-e prints in major collections show aigami passages that have shifted to pale grey-green or near-white, with blue surviving only on sheets kept folded or shelf-protected since printing. Raman-spectroscopy analysis of Edo-period prints has confirmed the widespread presence of natural colorants persisting alongside early synthetic dyes, consistent with aigami’s documented role through the early nineteenth century.

The pigment was effectively displaced by Prussian blue around 1830. Imported through the Dutch Dejima station in Nagasaki and adopted rapidly by the Edo print industry, the chemically more stable iron-cyanide pigment took over the blue passages of woodblock printing within a single decade. Hokusai’s Great Wave off Kanagawa (ca. 1830-32), the most famous Japanese print of all, uses Prussian blue rather than aigami specifically because the print is meant to read as blue for centuries rather than years; the artist’s late Mount Fuji series of 1830-32 generally marks the transition. Aigami persisted in folk and textile use into the early twentieth century but is essentially extinct as a printmaking pigment now, surviving mainly in historical-reconstruction work by specialist printmakers.