Description

C.I. Direct Blue 129 is a high-performance, water-soluble direct dye belonging to the azo chemical class. This dye is valued for its excellent substantivity to cellulosic fibers, providing deep, vibrant blue shades with good wash and light fastness properties. It is primarily used in the textile industry for dyeing cotton, viscose, and other regenerated fibers, as well as in the paper and leather industries. Our supply ensures consistent quality and reliable performance for demanding industrial applications.

Application

• Textile Dyeing: Primary application for exhaust and continuous dyeing of cotton, rayon, and other cellulosic fabrics.
• Paper Coloring: Used for surface coloring and mass tinting of paper and paperboard products.
• Leather Finishing: Imparts color to leather goods in the tanning and finishing processes.
• Ink Formulation: A colorant component in the manufacture of certain inks and toners.
• Biological Staining: Potential use as a histological stain in laboratory settings.
• Specialty Applications: Used in the coloration of non-woven materials and certain types of wood.

Basic Information

Product Name	C.I. Direct Blue 129
CAS No.	71838-51-2
Molecular Formula	C₃₂H₂₀N₆Na₂O₈S₂
Molecular Weight	750.65 g/mol
Synonyms	Direct Blue 129; Direct Blue 129 (C.I.); Direct Blue 129, disodium salt; Benzenesulfonic acid, 4,4'-[1,8-dihydroxy-3,6-disulfo-2,7-naphthalenediyl)bis(azo)]bis-, disodium salt; C.I. 24155; Direct Blue 2B; Sirius Blue S-GR; Solophenyl Blue BL
EINECS	Contact for details

Quality Control

Our C.I. Direct Blue 129 is manufactured under a strict quality management system to ensure batch-to-batch consistency and performance. Each lot is tested against rigorous internal specifications for key parameters including color strength, shade, solubility, and impurity profile. A Certificate of Analysis (COA) documenting purity, physical properties, and conformance is provided with every shipment to guarantee product integrity for your processes.

Storage

Preserve in a tightly closed container, protected from light. Store in a cool, dry, and well-ventilated area at room temperature (15-25°C). Keep away from strong oxidizing agents. The product is hygroscopic (moisture-sensitive); ensure containers are sealed after use to prevent moisture absorption and caking.

Specification

Item	Specification
Appearance	Dark Blue to Bluish-Black Powder
Identification (IR)	Conforms to Standard
Color Strength	100 ± 3% (vs. Standard)
Shade	Conforms to Standard
Moisture Content	≤ 5.0%
Water Insoluble Matter	≤ 0.5%
Solubility in Water	Complete (at specified concentration)
pH (1% Solution)	6.0 - 8.0
Heavy Metals (as Pb)	≤ 50 ppm

Note: Specifications can be tailored. Please contact us for the detailed technical data sheet of a specific grade.