noun
indigo-dye byproduct; lime-fermented indigo leaf mixture after dye precipitation
Technical term from traditional indigo dyeing (藍染め). Refers to the residual mixture of lime and fermented indigo leaves left after the indigo pigment has settled out. Not a common everyday word.
藍染めの工程で、藍汁は染料が沈殿した後に残る。
In the indigo dyeing process, 藍汁 remains after the dye has precipitated.
Compound of 藍 (indigo) and 汁 (juice, liquid), literally 'indigo liquid'. The alternate spelling 藍澱 uses 澱 (sediment) to highlight the settled nature of the substance.