Acid blue 1

Acid Blue 1 (CAS 129-17-9) is a synthetic triarylmethane dye also known commercially as Blue 7, Blue 9, Blue 25, and Blue 40. It carries the EC number 204-934-1 and the molecular formula C27H32N2O6S2.Na. It is not assigned an E-code for food use in the EU.

In textile and leather processing, Acid Blue 1 bonds to protein and polyamide fibres under acidic conditions, producing stable blue shades with good wash fastness. In printing and packaging, it functions as a soluble colorant in ink formulations where consistent hue and dye solubility are critical to colour reproducibility across substrates.

Acid Blue 1 is supplied as a crystalline powder and falls under HS code 32041200 for customs classification. Procurement should confirm REACH compliance and supplier Safety Data Sheet documentation before import into the EU. Packaging formats and available dye strength grades vary by supplier and should be confirmed at the time of enquiry.