BLUE (ĀBĪ)
Blue (ābi) is explained in 18th and 19th century in Resāleh-ye khošnevīsī (1120 A.H./1708 A.D.), and Resāleh Dar Bayān-e Rang Kardan-e Kāğaḏ (19th century), using indigo dye as follows:
اگر آبی خواهد آب نیل از خم گرفته در ظرف انداخته و اندک آبی به آن ضمّ کرده رنگ کند. و اگر آبی تَرَک خواهد بیشترک آب بیندازد تا آبی دلخواه برآید
To achieve a blue hue, take indigo dye and place it in a container. Add a small amount of water, then dip the paper into the solution and dye it. If a lighter shade of blue is desired, gradually add more water until the desired color is achieved.
Experiment:
To begin, take indigo dye powder or concentrated blue indigo dye. Add a small amount of water and stir to achieve a consistent solution. Gradually add more water to create dark, medium, and light indigo dye variations. For different shades of blue indigo dye, immerse the papers in the dye bath to attain the desired hue. To achieve a more consistent color shade, dip the paper in the dyebath and let it dry vertically.