indigo

Randugunting Sugar Mill was established in 1870. It initially processed crops from the Randoegoenting plantation in Yogyakarta and Tjandi Sewoe in Klaten. Both plantations initially produced indigo, which is a plant used to produce clothing dye.

Indigofera tinctoria is a species of plant that was one of the original sources of indigo dye. Dye is obtained from the processing of the plant’s leaves. They are soaked in water and fermented in order to convert the glycoside indican naturally present in the plant to the blue dye indigotin. The precipate from the fermented leaf solution is mixed with a strong base, such as lye. Indigotin, the blue dye, is not very soluble in neutral or acidic conditions, but in alkaline solution it precipitates more readily.

Indican is a colourless organic compound. Its most significant reaction is a hydrolysis to yields glucose and indoxyl. Once formed, the indoxyl is oxidized by atmospheric oxygen to give blue indigo dye.