Blaudruck/Modrotisk/Kékfestés/Modrotlac, which translates as blueprint or blue-dyeing, refers to the practice of printing a dye-resistant paste onto a cloth before it is dyed indigo. The paste prevents the dye from penetrating the design. To apply the designs onto the cloth, practitioners use hand-crafted blocks up to 300 years old, featuring regionally-inspired patterns, generic designs or Christian motifs. Nowadays, the practice is mainly conducted in family-owned workshops, run by the second to seventh generation of printers, and traditional knowledge is still based on (mainly family-owned) journals dating back to the nineteenth century.

on this subject: https://ich.unesco.org/en/RL/01365