Acid blue 3

Acid Blue 3 (CAS 3536-49-0) is a synthetic triarylmethane dye supplied as a calcium salt, also identified under the names CI 42051, C.I. 42051, l-blau3, and bluezn3. It carries no current E-code designation and is classified within the Pigments and Colorants category for industrial supply.

In textile and leather processing, Acid Blue 3 bonds to protein and polyamide fibres under acidic conditions, producing stable blue shades with controlled depth of shade. In personal care formulations, it functions as a surface-active colorant, modifying substrate wetting behaviour to ensure uniform colour distribution across hair or skin-contact products.

Acid Blue 3 is subject to REACH registration requirements for EU supply and must comply with applicable regional colorant regulations before use in cosmetic or food-contact applications. Procurement teams should confirm grade specification and lot documentation at point of order, as regulatory acceptance varies by end-use sector and jurisdiction.