Section
| HS Code | 356328 |
| Product Name | Acid Black ATT |
| Color Index Name | Acid Black 194 |
| Product Category | Acid dye |
| Chemical Class | Metal-complex acid dye |
| Cas Number | 1064-48-8 |
| Einecs Number | 263-329-4 |
| Physical Form | Powder |
| Appearance | Black powder |
| Color Shade | Black |
| Water Solubility | Soluble in water |
| Primary Application | Dyeing of leather, wool, nylon, and silk |
| Dyeing Method | Exhaust dyeing |
| Application Ph Range | Weakly acidic to neutral |
| Light Fastness | Moderate to good |
| Washing Fastness | Good |
| Storage Conditions | Store in a dry, cool, and ventilated place |
As an accredited Acid Black ATT factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Acid Black ATT is supplied in 25 kg net woven bags with inner plastic liners, sealed for safe transport and storage. |
| Container Loading (20′ FCL) | Acid Black ATT loaded in a 20′ FCL container, palletized 25 kg bags/drums, approx. 18–20 MT net, seaworthy packing. |
| Shipping | Ship Acid Black ATT in sealed, properly labeled containers, protected from moisture, heat, and direct sunlight. Avoid dust generation and container damage. Verify hazard classification against the current SDS and comply with applicable DOT, IATA, and IMDG requirements; use non-hazardous general cargo documentation only when confirmed. |
| Storage | Store Acid Black ATT in a cool, dry, well-ventilated area, away from direct sunlight, heat, and moisture. Keep containers tightly closed, clearly labeled, and in original or compatible packaging. Separate from strong oxidizers, acids, alkalis, food, drink, and animal feed. Avoid dust generation, prevent spills, use appropriate PPE, ensure good housekeeping and spill-control supplies, and follow the SDS and local regulations. |
| Shelf Life | Shelf life: 24 months when stored in original sealed packaging under cool, dry conditions, away from light and moisture. |
The drum exhaustion curve for C.I. Acid Black 210, marketed as Acid Black ATT, on chrome-tanned shaved leather shifts sharply as float pH falls below 4.2. In a 2000 mm diameter stainless steel hide-processor drum operating at 10–12 rpm, the working float is typically 150–200% based on shaved wet-blue weight and is heated from 20°C to 60°C at 2°C per 5 min. Acid Black ATT is applied at 2.5–4.0 wt% on shaved wet-blue weight for full black shades; additions of 1.0–2.0 wt% produce deep greys and brown-black blends when a carbon-black-free shade is required for edge buffing. After 40 min at 60°C, fixation is forced by adding 0.5 wt% formic acid as a 1:10 dilution over 15 min to a final pH of 3.6–3.8. The usable pH window is narrow: residual alkalinity from neutralization that holds pH above 4.8 increases grain penetration but reduces surface depth, while over-acidification below 3.5 promotes dye aggregation and bronzing on the grain side. Anionic acrylic retanning polymers applied before dyeing suppress Acid Black ATT uptake by 20–35% through competition for cationic chromium sites, and a 0.5–1.0 wt% sodium formate buffering treatment is required when wet-blue has been stored for more than 30 days. Cationic fixatives and cationic fatliquors must not be dosed in the same float because sulfonated Acid Black ATT forms insoluble complexes that deposit as uneven, grey-streaked patches on the grain. Standards governing this application include ISO 11640:2018 for to-and-fro rubbing, ISO 105-B02:2014 for artificial light fastness, EN ISO 17234-1:2015 for reductive cleavage of banned aromatic amines under REACH Annex XVII Entry 43, ZDHC MRSL Version 3.1, and the OEKO-TEX LEATHER Standard. Terminal products include full-grain upholstery leather, shoe upper leather, belt leather, and leather goods; furniture leather cut-parts requiring lightfastness of grade 4 or higher on the Blue Wool scale should be rejected because Acid Black ATT typically reaches only grade 3–4.
| Addition rate (wt% on shaved wet-blue) | Exhaustion at pH 4.2 (%) | Dry rub ISO 11640 (grey scale) | Wet rub ISO 11640 (grey scale) | Lightfastness ISO 105-B02 (Blue Wool) |
|---|---|---|---|---|
| 1.0 | 88–92 | 5 | 4–5 | 3 |
| 2.5 | 93–96 | 4–5 | 4 | 3–4 |
| 4.0 | 95–98 | 4 | 3–4 | 3 |
Mill data compiled from technical service bulletins show batch-to-batch variation of ±0.5 grey scale units when drum loading is not corrected for shaved thickness and chrome content. For low-chrome or rechromed lots, an additional 0.5 wt% Acid Black ATT is necessary to maintain equivalent visual depth at the same pH endpoint. In-line pH control using industrial titrators with automatic formic acid dosing reduces bronze-fault claims because manual acid addition onto the hide surface creates local pH pockets below 3.2, especially in 2500 kg commercial drums with mixing dead zones near the door. Water hardness above 150 mg/L CaCO₃ in the float should be sequestered with 0.3–0.5 g/L of a phosphonate chelant before dye addition to prevent undesirable lake formation on flesh-side fibres.
Exhaust dyeing of polyamide 6.6 warp-knit fabric in rope form with Acid Black ATT requires strict pH buffering at 4.5–5.5 because the amino end-group concentration in the fiber, typically 40–60 meq/kg for PA6.6, controls initial strike rate. In a soft-flow jet-dyeing machine with 1:10–1:15 liquor ratio, the bath is heated from 40°C to 98–100°C at 1.5–2.0°C/min and held for 45–60 min. An anionic leveling agent based on fatty amine ethoxylate is dosed at 1–2 g/L to retard barrel and rope marking. Acid Black ATT addition is 1.0–3.0% owf: 1.0% gives a medium grey, while 3.0% on 200 g/m² warp knit yields a dense black after fixation. Water hardness above 150 mg/L CaCO₃ causes dye aggregation and must be chelated with 0.5 g/L of a phosphonate-based sequestrant before acid addition. Without anionic after-fixation with synthetic tanning agent, washfastness under ISO 105-C06 A2S:2010 is 3–4; after-fixation at 2.0% owf raises the result to 4–5. The relevant compliance set is OEKO-TEX Standard 100 Annex 4 class II, ZDHC MRSL Version 3.1, REACH Annex XVII Entry 43 for reductive amine cleavage, and AFIRM RSL 2024 for finished textiles. Terminal product categories include nylon sports outerwear linings, luggage webbing, technical socks, and garment linings; chlorine-sensitive swimwear is not recommended because wet fastness and chlorine fastness under ISO 105-E03:2010 are marginal for spandex-containing constructions. Machine-specific failure is concentrated at rope circulation times above 2 min, where internal temperature difference between the rope core and the nozzle path exceeds 2°C and produces crack marks on heavyweight 240 g/m² interlock panels.
Substitution of solvent-soluble nigrosine with water-soluble Acid Black ATT in furniture-grade stains begins with dissolution at 60–70°C in a 50:50 demineralized water/isopropanol carrier. Stock solutions are prepared at 10–15 g/L and passed through a 25 µm bag filter before letdown to ready-to-use stain at 5–12 g/L. Spray application through a 1.0 mm nozzle at 0.8–1.2 bar deposits 60–80 g/m² wet film; flash-off at 20°C and 50% RH for 20 min precedes sealing with a two-component polyurethane or acid-catalyzed varnish. Grain raising on water-based stains is controlled by adding 10 wt% butyl glycol to the letdown water; dye migration into the PU topcoat occurs when residual moisture exceeds 12% before sealing. The process carries EN 71-3:2019+A1:2021 toy safety obligations for metallic migration, DIN 68861-1 for furniture surface performance, and VOC caps under Directive 2004/42/EC Annex IIA category h for wood coatings. Interior furniture frames, veneered panels, decorative boxes, and non-toy woodenware are typical terminal products; exterior window frames and door skins are excluded because Acid Black ATT lightfastness on wood remains below 4 Blue Wool and will grey after 2–3 months of northern-hemisphere daylight exposure. Cross-grain penetration on open-pore oak at 80 g/m² wet laydown creates visible differential colour when the sealing varnish is sanded through, so closed-pore ash or rotary-cut birch veneer requires a 30% reduction in dye concentration to prevent excessive grain accent.
Where alcohol-rich flexographic ink vehicles demand an anionic dye that remains in solution at pH 8.5–9.5, Acid Black ATT is predissolved in demineralized water/propylene glycol at 70°C and then milled into a styrene-acrylic varnish at 8–15 wt% of total liquid ink. High-concentration bases are prepared at 20–25 wt% dye content with 10–15% propylene glycol to prevent drying on the sides of mixing vessels. After high-shear mixing at 2000 rpm for 20 min, the finished ink is adjusted to 45–70 s Zahn cup #2 viscosity and 36–40 mN/m surface tension. Flexographic printing on coated board uses an anilox roll of 180–220 lpi and chamber doctoring at 8–10 g/m² wet film; forced-air drying at 80–90°C is required to reach 1.0–1.5 g/m² dry dye laydown. Calcium and magnesium hardness above 100 mg/L CaCO₃ precipitates Acid Black ATT as an insoluble lake, so demineralized water and 0.2–0.5% chelating agent are mandatory. Compliance is anchored to the EuPIA Exclusion Policy for Printing Inks, Swiss Ordinance SR 817.023.21 for printing inks on non-food packaging, and FDA 21 CFR 175.300 only where the printed surface is separated by a functional barrier from food. Corrugated outer boxes, paper shopping bags, printed paper labels, and coated board displays are terminal products; low-migration UV-curable food-contact inks are outside this application window because Acid Black ATT has not been validated for direct-food-contact migration limits. Foam generation in high-speed gravure trays at 300 m/min press speed must be suppressed with 0.1–0.3% silicone-free defoamer, because foam entrapment in the doctor blade gap causes streak defects that are not resolved by viscosity adjustment alone.
Charge competition between sulfonated Acid Black ATT and AKD sizing emulsion at pH 7.0 makes beater dyeing the least robust application for this dye. Published data for Acid Black ATT in alkaline paper furnishes is limited; the commonly observed acid dye operating window of 0.1–0.5 wt% on dry pulp is therefore derived from general behavior on bleached kraft fibre rather than dye-specific trials. In beater addition, the dye is injected after the cationic retention aid poly-DADMAC at 0.3–0.5 kg/t, with stock pH held between 6.5 and 7.5 to avoid hydrolysis of AKD. Surface size press application uses 2–5 g/L Acid Black ATT in a 5–8% oxidized CMC starch solution at 60°C on a machine running 800–1200 m/min. Water bleed is controlled by fixing agents but remains the principal limitation; paper dyed with Acid Black ATT is not suitable for aqueous food contact. Compliance for non-food decorative papers references FDA 21 CFR 176.170 for paper and paperboard components in contact with food, EU 1935/2004 for food-contact materials, and EN 646:2018 for tissue dye bleed. Terminal products include poster paper, decorative tissue, colored corrugated liner, and non-food packaging paper. Retention efficiency on kraft fibre is below 70% without cationic fixative, and the resulting white-water tint creates cross-contamination on grade changes that requires three machine chest turnovers between colours.
Loose-stock wool dyeing in top dyeing vessels at 98°C with Acid Black ATT proceeds through rapid initial strike on fiber surface, requiring a restrained ramp rate of 1°C/min after 60°C to avoid skittery dye uptake. The vessel is run at 1:12–1:20 liquor ratio with 0.8–3.0% owf dye; pH is buffered to 4.5–5.0 with acetic acid/sodium acetate, and the temperature is held at 98°C for 60 min before cooling to 70°C over 30 min. Process safety at pH below 4.0 is poor because wool fibre tensile loss accelerates with hydrolytic damage; prolonged boil beyond 90 min does not improve depth but increases fibre yellowing under ISO 105-B02:2014. Dye exhaustion on untreated wool typically exceeds 95%, but shrink-resist-treated stock with high anionic surface charge can show 10–20% lower uptake and requires an additional 0.5% Acid Black ATT. Compliance for finished felt and nonwovens is assessed against OEKO-TEX Standard 100 Annex 4 class I for infant-contact textiles, ISO 105-C06 A1S:2010 for wash fastness, ISO 105-B02:2014, and REACH Annex XVII Entry 43 for reductive amine cleavage. Industrial felt, piano felt, compression gaskets, and technical nonwoven felts are terminal product categories.
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Acid Black ATT is a chromium-complex disazo acid dye, generally listed as C.I. Acid Black 194 and assigned Chemical Abstracts Service registry number 61931-02-0. The commercial model designation Acid Black ATT is used by multiple suppliers; no single manufacturer owns the term, and part numbers vary. The dye is produced as a dark powder or granule with anionic sulfonate functionality and a chromium(III)-chelated azo chromophore. The chromium complex broadens the visible absorption band around the 550–610 nm region and shifts the product’s performance envelope relative to non-metallized acid blacks such as C.I. Acid Black 1.
Physicochemical behavior is governed by the anionic sulfonate groups and the chromium(III) chelate. Aqueous stock solutions are stable under neutral to weakly acidic pH; strong electrolytes above 20 g/L can agglomerate the dye and reduce filtration stability. The dye is compatible with formic acid, acetic acid, anionic wetting agents, and selected nonionic dispersants, but not with strong reducing agents such as sodium hydrosulfite in concentrated stock solutions because demetallization occurs.
The product is intended for leather wet-end dyeing, particularly on chrome-tanned wet-blue, where it produces high-exhaustion neutral black shades without sodium sulfide reduction. Secondary textile usage covers polyamide 6, polyamide 6.6, and wool. This document covers model classification, incoming control specifications, process boundaries, and substitution differences.
Exhaustion on wet-blue is strongly pH-dependent. In a 3000-kg Y-type stainless steel drum rotating at 6–12 rpm with a float ratio of 1:5 to 1:8, the dye is pre-dissolved at 70–80 °C and introduced by peristaltic pump over 10–15 min. Initial bath pH is held at 4.5–5.0 with buffered formic acid or ammonium acetate. Under these conditions, Acid Black ATT commonly delivers 90–95% exhaustion within 45–60 min at 60–65 °C. At pH 5.5 and above, exhaustion drops sharply because the anionic dye has increased electrostatic repulsion with the increasingly negative leather carboxylate surface; visual assessment shows grain-to-flesh shading and reduced penetration into the reticular layer.
Field experience on production lots indicates that a drum rotational speed below 5 rpm or load above 80% of rated capacity produces core pale zones in folded neck areas. The processing window for reproducible shade is narrow; bath temperature should be maintained within ±5 °C of the set point. For chrome-tanned shoe upper leather, typical usage is 2.0–4.0% on wet-blue shaved weight; for full grain upholstery leather a lower range of 1.5–2.5% is used to keep the grain from becoming overloaded. If shade correction is required, pH is reduced in increments to 3.8–4.2 with diluted formic acid rather than increasing dye addition beyond 5.0% on wet-blue weight. Higher additions increase chromium load in spent bath and do not proportionally deepen the perceived black, because the leather surface reaches a saturation point.
The product should not be combined with cationic retanning agents before dyeing. Cationic polymers precipitate the anionic dye and produce grain specks and reduced exhaust; if cationic retanning is needed, it must precede dyeing by a separate wash and neutralization step. For mill production, batch-to-batch shade drift of ΔE CMC 0.3–0.6 is controlled by checking incoming tinctorial strength against a retained master standard under AATCC EP 6 and adjusting the quantity by weight.
On polyamide 6 and 6.6 woven or knit goods, Acid Black ATT is applied in overflow jet or beam dyeing machines at 98–100 °C. Unlike Acid Black 1, the chromium-complex dye does not require a strongly acidic strike; a bath pH of 6.0–7.5 with ammonium sulfate as acid donor is sufficient for deep shades. However, the metallized chromophore has lower migration during the boil; levelness depends on controlled temperature ramp and leveling agents rather than extended migration time. A standard ramp starts at 40 °C, holds for 10 min with 1–2% of an amphoteric leveling agent, then rises at 1–2 °C/min to 98 °C and holds for 45–60 min. Downstream wetfastness under ISO 105-C06 A2S is typically higher than for non-metallized acid blacks because the larger chromium-coordinated structure diffuses less readily during washing.
For wool garment dyeing, the bath is set at 40 °C, pH adjusted to 5.5–6.0, and dye added over 10 min. Heating is limited to 1–2 °C/min; above 2 °C/min, tippy uptake on wool scales appears as darker fiber tips. The product has limited compatibility with high-affinity acid milling dyes in combination shades; if mixed, blocking can occur and shade may be batch-variable. In stock solution preparation, hard water above 150 mg/L CaCO₃ should be conditioned with a chelating agent, because calcium can precipitate sulfonated dye fractions and form specking on nylon fabric.
Commercial certificates of analysis for Acid Black ATT typically include the following controls; exact acceptance limits vary by producer, so the table below is a consensus range based on available technical bulletins, not a single supplier specification.
| Parameter | Consensus acceptance limit | Test method |
|---|---|---|
| Physical form | Dark black powder or granules | Visual |
| Moisture content | ≤5.0% w/w | ISO 787-2 |
| Water-insoluble matter | ≤0.5% w/w | ISO 787-3 hot extraction, residual calculation |
| pH of 1% aqueous dispersion | 7.0–9.0 | ISO 787-9 |
| Relative tinctorial strength | 100±3% versus master standard | AATCC EP 6 |
| Hexavalent chromium in dyed leather | <3 mg/kg | ISO 17075-1:2017 |
Total chromium content in the dye powder itself is determined by ISO 17072-2 after alkaline extraction; the dye contains chromium(III), not chromium(VI), but safe processing must still control oxidation. Storage at relative humidity above 60% may cause caking; caked material requires re-milling and increases dissolution time in 80 °C water beyond 30 min. Stock solutions are stable for 8–12 hours if kept at 40–50 °C with slow stirring; beyond this, microbial growth in non-sterile water degrades solution reproducibility.
Acid Black ATT is not a drop-in replacement for Acid Black 1. The chromium complex has a broader visible absorption envelope and lower apparent color yield per unit mass; formulators typically move from 2.5–3.0% o.w.f. of Acid Black 1 to 3.5–4.5% o.w.f. of Acid Black ATT to achieve the same visual depth on nylon. Lightfastness under ISO 105-B02 is higher for Acid Black ATT, but the product’s lower anionic charge density alters the exhaust curve at neutral pH. In beam dyeing equipment, Acid Black 1 can be ramped from 40 °C to 98 °C in 20 min; Acid Black ATT requires 40 min or longer to avoid unlevel uptake. Wet crocking resistance under ISO 105-X12 improves with the chromium complex, but the product’s redrawn shade in pale combinations is duller and may not match bright greenish-black specifications.
For leather, substitution of Acid Black 172 with Acid Black ATT changes shade undertone from a brown-black to a slightly bluer black on chrome-tanned wet-blue. Published structural data for this specific comparison is limited, but commercial technical bulletins describe Acid Black 172 as a higher-molecular-weight anionic azo preparation, often selected for low-chrome leather lines. Acid Black ATT tends to build depth more rapidly at equal weight, but its chromium content requires stricter Cr(VI) monitoring. The choice between the two should be governed by the target leather article and effluent permit; both require alkaline hydrolysis controls after dyeing.
Compared with sulfur black, Acid Black ATT is applied under acid conditions and avoids sodium sulfide reduction. This difference removes sulfide oxidation demand from the spent bath and permits direct combination with acid syntans. Sulfur blacks produce high tinctorial strength on cotton but are not applicable to chrome-tanned leather in the same way; Acid Black ATT is selected for protein and polyamide substrates rather than cellulosic dyeing.
Regulatory classification for Acid Black ATT follows C.I. Acid Black 194 with CAS 61931-02-0. Chrome-tanned leather dyed with this product and placed on the EU market must meet the Cr(VI) restriction of <3 mg/kg under REACH Annex XVII. The dye itself introduces chromium(III); Cr(VI) is formed by oxidation when leather is exposed to high pH, UV, and high temperature after dyeing. Therefore post-dyeing operations should acidify leather to pH 3.5–4.5 and add 0.5–1.0% of an antioxidant or Cr(VI) inhibitor during fatliquoring. If leather is dried at elevated pH, Cr(VI) can exceed 3 mg/kg even though initial leather chromium(III) is stable. The product should not be used for food-contact materials, toys, or infant articles unless specific regulatory review is completed.
For effluent control, spent dyebath contains organic sulfonated color and chromium; conventional alkaline precipitation in a primary treatment unit removes chromium-bearing dye aggregates, but final discharge must be monitored with ISO 17072-2 for total chromium. Amine release from azo cleavage must be assessed using ISO 17234-1 where azoreductase degradation is suspected. Oxidative decolorization with sodium hypochlorite should be avoided because it can oxidize chromium(III) to chromium(VI) in the effluent; acid bisulfite reduction is preferred for chrome control.
On wet-white leather tanned with glutaraldehyde or synthetic tannins, Acid Black ATT does not have the same strong electrostatic attraction that occurs on chrome-tanned wet-blue. The bath pH must be lowered to 4.0–4.5 with formic acid before dye addition, and the dye should be applied at 50–55 °C rather than 65 °C to avoid surface strike. Exhaustion in wet-white systems is commonly 10–15% lower than on wet-blue under identical mechanical action, so addition levels are typically increased by 0.5% on shaved weight. A naphthalenesulfonate auxiliary at 1–2% improves penetration but reduces final bath exhaustion; residual color must be measured before drain. Vegetable-tanned leather requires even more careful control because high pH in vegetable tubs can shift the dye from its anionic state and cause bronzing.
The incompatibility boundary is defined by chromium extraction: prolonged drumming at temperatures above 70 °C or addition of strong reducing agents such as sodium hydrosulfite can demetallize the chromium complex, causing shade shift to a drab brown and releasing chromium into the bath. Strong cationic finishing resins applied before dyeing also lower uptake; the sequence should be dyeing, acid fixation, washing, then retanning/fatliquoring. If fixing with cationic agents is required for wet-rub fastness, it should be limited to 1–2% at 35 °C for 20 min; higher levels reduce lightfastness and may extract chromium from the dye.
Occupational hygiene monitoring during powder weighing should follow local dust exposure limits; local exhaust ventilation at 0.5 m/s capture velocity reduces respirable nuisance dust. Operators should use respirators meeting EN 149:2001+A1:2009 when local exhaust is not fitted; skin contact with concentrated powder should be prevented by chemical goggles and nitrile gloves.
