The imported pigment that became famous for its deep blue in nineteenth-century Japanese ukiyo-e prints was Prussian blue.
Prussian blue was developed in Europe around 1704 and entered Japan through Dutch trade. Japanese artists and printers valued it because it was more stable than many earlier organic blues, including the plant-based indigo commonly used in earlier prints. Its strong color helped transform landscape ukiyo-e during the early nineteenth century.
Hokusai used Prussian blue prominently in Thirty-Six Views of Mount Fuji, including The Great Wave off Kanagawa. Hiroshige also used the pigment extensively in landscape series. The new blue contributed to the visual identity sometimes called aizuri-e, or blue-printed pictures, although aizuri-e describes a style or color scheme rather than one particular pigment.
Prussian blue did not replace every traditional color. Ukiyo-e printers continued combining imported and locally available pigments, and color recipes varied among workshops. Conservation specialists can study pigment use to help date or authenticate impressions.