When the first shipments of Berlin blue arrived at the Nagasaki trading post in the late 1820s, the color dealers of Edo paid them little attention. Prussian blue — or bero-ai, as the Dutch traders called it — was merely another curiosity from the Western factories, no more remarkable than the glass lenses and woolen cloth that accompanied it. Nobody in those workshops along the Sumida River could have predicted that this unassuming powder would, within a single decade, redraw the visual grammar of an entire art tradition.
A Color That Changed the Frame
The genius of Prussian blue lay not in its hue alone but in its behavior on moistened paper. Unlike indigo extracted from ai grass — the traditional Japanese blue, prone to bleeding and fading — bero-ai held its saturation through repeated pressings. It accepted the baren’s pressure without breaking into uneven patches. For woodblock printmakers, this was transformative: suddenly a printer could fill an entire sky with a single uniform wash of blue, and the color would remain crisp from the first impression to the ten-thousandth.