Reactive blue 4

Reactive Blue 4 (CAS 13324-20-4), also known commercially as Procion Blue MX-R and Ostazin Brilliant Blue S-R, is a reactive dye that forms covalent bonds with substrate fibers to deliver durable, wash-fast coloration.

It is a standard reference dye in industrial dyeing operations and laboratory enzyme assay applications. In textile processing, it is applied to cellulosic fibers like cotton, viscose, and linen under alkaline conditions.

This process achieves deep blue shades with high fixation efficiency. Leather tanneries use it for through-dyeing and surface coloration where color fastness under wet conditions is a critical performance requirement.

In paper manufacturing, it is used for mass coloration and surface treatment of specialty papers where consistent hue and bleed resistance matter. It also serves as a substrate in biochemical assays.

This is particularly useful for detecting cellulase and other hydrolytic enzyme activity in research and quality control settings. Reactive Blue 4 is supplied as a powder or granular solid for industrial use.

It is typically provided in commercial dye concentrations standardized by dye content percentage. Technical and laboratory grades are both available depending on the specific application and purity needs.

Lab-grade material is used in enzyme substrate preparations requiring tighter purity specifications. This ensures consistent results in sensitive biochemical testing and high-end manufacturing processes.