To dye paper, they first had to reconstitute the indigo by dissolving it in an alkaline solution to produce "indigo white." Then they repeatedly soaked the paper in the liquor and rinsed it in water, which gradually imparted an increasingly dark blue color.
當紙張染色時，首先要將靛藍還原、溶解於鹼性水中，成為靛白隱色鹽，藉由一次次的浸染壓吸、水洗發色而逐漸加深色澤。