Catechu (gambir extract)

Amount used
The same weight of the dough

Summary
This dye is obtained from Gambir, a member of the Acanthaceae family grown in the tropical regions of Southeast Asia. The leafy branches and bark are boiled down and then dried. Because it is rich in tannin, it has long been used for leather tanning and as a stomachic medicine called "Asenyaku" (阿仙薬).

Dyeing method
Boil it in hot water for 15 mins and later filter it. The higher the temperature of the liquid, the darker the color.