Hierarchy classification:

1. top of the aat hierarchies
2. Materials Facet
3. Materials (hierarchy name)
4. materials (substances)
5. [materials by function]
6. colorant (material)
7. pigments
8. [pigment by color]
9. blue pigment
10. organic blue pigment

Additional parents:

1. top of the aat hierarchies
2. Materials Facet
3. Materials
4. materials
5. materials by function
6. colorant
7. colorant for dye and pigment
8. indigo

Anotations

Scope note:

A dark bluish purple, synthetic, water soluble pigment composed of the sodium sulfonate salt of indigotin. First prepared in 1740 by Barth, it was the earliest synthetic acid dye. It was used to color wool and silk; it is not lightfast and has poor washfastness. It is still used for coloring nylon sutures, food, drugs, and as a biological stain and as a detection reagent for nitrates and chlorates.