Bromo Indigo in Granular Form: Field Notes, Specs, and Real-World Use

If you follow vat dyes the way I do, you’ve probably seen how demand for stable, low-dust granules keeps rising in denim and workwear. I took a closer look at indigo blue granular company offerings—specifically a Bromo Indigo (C.I. Vat Blue 5) from Hebei—and, to be honest, the shop-floor details matter more than the brochure gloss.

What it is (and why mills care)

Product: Bromo Indigo; also known as Vat Bromo-Indigo; C.I. Vat Blue 5. Molecular formula: C16H6Br4N2O2. CAS No. 2475-31-2. HS code 3204151000. Origin: HEBEI FUXIN INTERNATIONAL TRADE CO., LTD., A-1205, MCC World Grand Plaza, 66 Xiangtai Road, Shijiazhuang 050023, China. Many customers say the granules flow consistently through feeders—less mess, fewer stoppages. In denim lines, that’s gold.

Quick specification snapshot

How mills actually run it (process flow)

• Materials: Bromo Indigo granules, NaOH, sodium dithionite (hydrosulfite), wetting agent, soft water.
• Reduction: 55–60°C, pH 11–12; vat to leuco form (keep redox at ≈–650 to –700 mV).
• Dyeing: Rope or slasher—multiple dips/airings for shade build; pick-up 70–85% typical.
• Oxidation: Air or H2O2 mild; then soaping at 95°C to clear.
• Testing: ISO 105-C06 wash; ISO 105-B02 light; AATCC 61/8, ISO 105-X12 rub fastness.
• Service life: Fabrics retain shade 30–50 home launderings under normal care (depends on shade and afterwash).
• Industries: Denim, workwear, home textiles; I’ve seen knit experiments too—surprisingly clean tone.

Application scenarios and advantages

• Rope dyeing: Consistent oxidation yields classical indigo-blue cast with slightly cooler undertone.
• Slasher dyeing: Lower dusting helps sensors stay clean—operators appreciate that, frankly.
• Garment dyeing: For vintage looks; responsive to controlled abrasion and enzyme finishing.
• Edge: Shade stability, good granule flow, and robust wash/rub fastness after proper soaping.

Vendor comparison (indicative)

Customization

Typical requests: tighter particle-window for automated feeders, shade cast adjustment, and moisture control for humid plants. The indigo blue granular company team can provide COA, SDS, and test reports aligned with ISO/AATCC—ask for latest versions (these do update).

Case notes and test data

• Denim mill (South Asia): Rope dye, 8 dips, 75% pick-up. Wash fastness (ISO 105-C06): 4–5; Dry rub (ISO 105-X12): 4; Wet rub: 3–4. Operators reported fewer feeder alarms after switching to granules.
• Workwear fabric (EU): Slasher line; after soaping at 95°C, light fastness (ISO 105-B02): 6–7. Customer feedback: “shade repeatability improved across lots.”

Compliance, safety, and trends

Docs available on request typically include COA, SDS, and statements for REACH and ZDHC MRSL alignment. Always verify current editions. Industry trend-wise, I’m seeing stronger asks for traceable supply chains and tighter dust specs—areas where the indigo blue granular company model (granular, controlled particle size) fits neatly.

Authoritative citations

1. ISO 105-C06: Tests for color fastness to domestic and commercial laundering. https://www.iso.org
2. ISO 105-B02: Tests for color fastness to artificial light: Xenon arc. https://www.iso.org
3. ISO 105-X12: Tests for color fastness to rubbing. https://www.iso.org
4. AATCC TM61/8: Colorfastness to laundering and crocking. https://www.aatcc.org
5. ZDHC MRSL (current version): Manufacturing Restricted Substances List. https://www.roadmaptozero.com
6. REACH Candidate List (SVHC). https://echa.europa.eu