The colour blue is known in Japanese as ao, or aoi. In some cases aoi is also used to indicate things that are green in colour. Although in modern Japanese there is a term for green (midori), it is not always used in the same manner as in Hebrew or English. The word midori first appeared during the Heian era, (794-1185), but initially indicated shades of blue. The distinction between blue and green, customary today, appeared only at the end of World War II.
Although the Japanese now distinguish between blue and green, they still use the term aoi to describe the colour of some vegetables, for example, apples and plants. Green traffic lights are described as ao shingô, but the colour green for cars is defined midori. Similarly, there are many terms in the language that describe shades of blue and green. In addition, Aoi means "youth". For instance, the song "aoi kajitsu" is about a young girl. Similarly, the biography of Yamaguchi Momoe (born 1959), who sings the above mentioned song, is called "Aoi Toki" (My Youth).
Aizuri-e (literally, indigo pictures) are Japanese prints done in shades of blue. The development of the blue prints has to do with the import of Prussian blue dye from Europe. The colour was invented by the German alchemist Johann Konrad Dippel (1673-1734) in 1704. This pigment had several advantages over the indigo colour which was in use in many Japanese woodblock prints of the early 18th century. Indigo was produced from petals of Commelina and other plants but they provided only the dark blue shade. By comparison, synthetic Prussian blue was bold and vivid, with a wide range of tones and more resistance to fading. Prussian blue is particularly useful for depicting deep water, oceans, rivers and blue skies, and thus, it became a major factor in shaping the genre of landscape prints (fûkei-ga) belonging to ukiyo-e (Pictures of the Floating World). This chemical pigment was known in Japan as Berurin-ai (or Beru-ai; Berlin blue). As one might guess, Berurin is a corruption of the word Berlin.
In the second half of the 18th century, Prussian blue was mentioned in several painting guides, often specifying that it was difficult to obtain because, imported by the Dutch from Europe, it came from afar. Then in the 1790's artists began experimenting with Prussian blue. Ukiyo-e researcher, Yoshige Teruji, quotes Seisôdô Tôho, a bookseller and a haiku poet from the city of Edo. Seisôdô claimed in a collection of articles that the Prussian blue was imported by the artist Ôoka Umpo (1765-1848) in 1829 and that Umpo made use of it in his surimono (lit. printed matter) prints. Surimono were greeting cards, invitations or announcements about different events. However, it seems that artist, Nagayama Kôin of Osaka, used the pigment in a surimono as early as spring of 1825. In fact, it was brought to Edo only in 1829 and there too was first used in surimono prints. Surimonos were printed in small quantities for private distribution, hence the high cost of the blue pigment was insignificant. In 1830, Iseya Sôbei, a publisher of fan prints (uchiwa-e), first used Prussian blue in a print designed by Keisai Eisen (1790-1848). Eisen created fan-shaped aizuri-e prints using only the imported blue which led to a surge in their popularity. It also became fashionable to use the pigment in prints of figures and a year later of landscapes. (Hokusai: Life and Work, by Richard Lane, E. P. Dutton, 1989, pp. 184-5.)
Katsushika Hokusai (1760-1849) was also among the artists who designed the first blue prints. In 1831, the publisher, Nishimuraya Yohachi, placed an advertisement in a novel by Ryûtei Tanehiko, publicizing the emergence of a new series of prints: "The Thirty-Six Views of Mount Fuji, by the old man zen Hokusai Iitsu, single sheet prints in blue, each featuring a different design - now being published." (Matthi Forrer, Hokusai, Rizzoli, 1988. P. 263).
The reference, in the advertisement, to the colour is particularly interesting because the word aizuri, meaning "Indigo," is used and not Berurin-ai. Nevertheless, it undoubtedly indicated the synthetic Prussian blue and not the colour produced from plants. Indeed, ten prints from the series, "Thirty-Six Views of Mount Fuji," among them, the print known as "The Great Wave at Kanagawa," were printed in Prussian blue. The colour appears also in Japanese prints from the collection of Philipp Franz von Siebold, who arrived at the island of Deshima in Japan with a Dutch trade group visiting Edo in 1826.
In 1841, the Tokugawa government, issuing the sumptuary laws known as Tempo reforms, prohibited the use of flashy colours in woodblock prints. As a result, some argued, aizuri-e prints became popular as an alternative to colour prints. But the wonderful aizuri-e prints of Katsushika Hokusai indicate that this technique had been popular even before the regulation in question. Therefore, the theory claiming that the production of aizuri-e prints was a consequence of the new regulations is no longer widely accepted. At the same time, there is no doubt that it was cheaper to produce monochrome prints than coloured ones.
Utagawa Hiroshige (1797-1858) was another artist experienced in designing aizuri-e prints. This can be seen in his fan-shaped print depicting the view of the Kinkizan Temple at Enoshima Island (1855). Hiroshige also used Prussian blue combined with other colours like red and yellow in his landscape prints. Other well-known Japanese artists experimenting in designing aizuri prints include Utagawa Kunisada (1786-1865) and Utagawa Sadahide (1807-1873). Although using only one type of blue colour, they were able to achieve light and shadow by repeatedly printing it in certain areas or by gradual colour transitions (bokashi).
Undoubtedly, the synthetic blue pigment was expensive and considered a luxury. So, at first, it was used sparingly in paintings and later in surimono prints and luxury editions of individual woodblock prints, designed for a small audience. Later, however, the success of the first artworks containing Prussian blue led to its commercial import and a decline in price. This then allowed publishers to use the colour more liberally in the production of the monochromatic blue prints.
Dr. Ilana Singer Blaine, Tikotin Museum of Japanese Art