Dyeing silk yarn with indigo at the Yamazaki Seiju studio in Gunma prefecture. The dyer is his son, Yamazaki Kazuki. The indigo is sukumo a natural indigo. The additives are fusuma (cooked wheat bran or mash). This starch is used to feed the bacteria and Ca(OH)2, (sekkai) the liquid that has been leached from wood ashes.