Bokashi (Japanese: ぼかし) is a technique used in Japanese woodblock printmaking. It achieves a variation in lightness and darkness (value) of a single color by hand applying a gradation of ink to a moistened wooden printing block, rather than inking the block uniformly. This hand-application had to be repeated for each sheet of paper that was printed.
The best-known examples of bokashi are in the 19th-century ukiyo-e works of Hokusai and Hiroshige, in which the fading of Prussian blue dyes in skies and water create an illusion of depth.
Gradations can be created on the blocks themselves using the itobokashi technique, or brushed on by hand using fukibokashi. They can also be done freehand directly onto a print, without using a printing block.
Fukibokashi requires gradations of ink to be applied to the printing block. This is not a precise technique; its results are inconsisistent from print to print.
The technique ichimoji bokashi (一文字ぼかし, "staight-line bokashi") is the one associated with the works of Hokusai and Hiroshige. Ink is applied only to one end of the brush's bristles, and the brush is drawn across the desired portion of the printing block; this area is first wetted with a zōkin cloth, so that the ink bleeds somewhat across the wet area. This creates a gradation at the width of the brush.
In futa-iro bokashi (二色ぼかし) two colours are worked toward each other, achieved by applying two inks to opposite edges of the brush. In hakkake bokashi a flat colour is printed, and then the same printing block is washed and re-brushed with a bokashi effect to overprint over the first; this technique is seen on the dark peak of Mount Fuji in Hokusai's Fine Wind, Clear Morning.