Liquid Sulfur Black (Pre - Reduced Leuco Sulfur Black)

Liquid Sulfur Black (C.I. Sulfur Black 1, CAS: 1326-82-5) is a pre - reduced leuco solution of traditional sulfur black, a ready - to - use liquid dye with standardized concentration, mainly designed for textile dyeing to simplify processes and improve environmental performance .

Core Properties

- Appearance: Uniform black viscous liquid; typical pH 13.0-14.0, stable viscosity, no sedimentation.

- Key Trait: Pre - reduced to soluble leuco form; contains built - in reducing agents (e.g., sodium polysulfide), requiring no on - site sodium sulfide dissolution .

- Basic Metrics: Common active content ≥ 50%, density ~1.2-1.3 g/cm³; fastness: light 4-5, washing 3-4, dry rubbing 2-3, wet rubbing 2.

Synthesis & Core Advantages

- Synthesis: Made by stabilizing the pre - reduced leuco solution of sulfur black with additives after sulfuration, oxidation, and precise reduction control.

- Advantages:

- Process - friendly: No on - site reduction/dissolution; shorter setup, lower labor, and better color consistency/penetration.

- Eco - better: Wastewater COD reduced by ~2/3 vs. powder; less H₂S odor and lower sulfur - containing discharge.

- Quality - up: Lower fiber brittleness risk vs. powder; more stable dyeing results.

- Cost - effective: Lower water/energy use; total cost lower despite slightly higher unit price.

Applications

Mainly for dyeing cotton, linen, viscose, and leather; ideal for denim yarn, piece goods, knitting, and package dyeing (e.g., beam, package dyeing) . Suitable for pad, exhaust, and rope dyeing; widely used in denim and mass - produced black cotton fabrics .

Usage & Notes

- Dyeing Process: Dilute directly with water; control bath pH 12-13, temperature 80-95°C; oxidize with air or oxidants (e.g., sodium perborate) post - dyeing; follow with anti - crisp treatment (urea + soda ash) and thorough washing.

- Precautions: Avoid over - oxidation (may cause color change); store sealed at 5-35°C to prevent freezing/heating degradation; keep good ventilation during operation .

- Packaging: 200 kg plastic drums or 25 kg iron drums; avoid leakage and contact with acids.

Comparison with Powdered Sulfur Black

Aspect Liquid Sulfur Black Powdered Sulfur Black

Usage Ready to dilute; no on - site reduction Needs sodium sulfide dissolution/reduction

Wastewater Lower COD, less sulfur - containing Higher COD, more sulfur - containing

Consistency High color stability; less color difference Prone to uneven dissolution and color variation

Labor/Cost Lower labor; lower total process cost Higher labor; higher water/energy cost

Storage Sealed, temperature - controlled Dry, cool storage; risk of dust

Key Standards

Complies with HG/T 4040-2022 for liquid sulfur black; meets OEKO - TEX Standard 100 and GOTS requirements for eco - textile applications .

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