Indigo

Indigo (CAS 482-89-3), also recognized commercially as FD&C Blue No. 2 and sold under the E132 designation as Indigo Carmine, is one of the oldest and most established blue colorants in industrial use.

Where is Indigo used?

• Textile manufacturing: defining colorant for denim, applied through vat dyeing to achieve the characteristic fading profile
• Leather and paper: uniform blue tones in decorative and functional grades
• Printing and packaging: base pigment in ink formulations
• The water-soluble sulfonated form, Indigo Carmine, colors tablets and capsules.

Good to know: Deep blue shades and batch-to-batch consistency are critical to brand color standards. Ingestible products are manufactured under FD&C and E132 approvals.

Commercial specifications

• Food and pharmaceutical grades conform to FD&C, E132, and USP specifications