Section
| HS Code | 633161 |
| Productname | Acid Black 210 |
| Colorindexname | C.I. Acid Black 210 |
| Casnumber | 99576-15-5 |
| Einecsnumber | 619-333-5 |
| Molecularformula | C34H27N7Na2O11S3 |
| Molecularweight | 851.79 |
| Chemicalclass | Azo acid dye |
| Appearance | Black powder |
| Colorshade | Black |
| Solubility | Soluble in water |
| Phvalue | 7.0-9.0 (1% aqueous solution) |
| Dyecontent | 95% min |
| Moisturecontent | 5% max |
| Insolublematter | 0.5% max |
| Application | Dyeing of leather |
| Storageconditions | Store in a cool, dry, well-ventilated place away from light |
| Stability | Stable under normal storage conditions |
As an accredited Acid Black 210 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Acid Black 210 is packaged in 25 kg net-weight moisture-resistant kraft paper bags with inner polyethylene liners for safe storage and transport. |
| Container Loading (20′ FCL) | Acid Black 210 is palletized and securely loaded into a 20′ FCL container with proper labeling and documentation for safe transport. |
| Shipping | Acid Black 210 is generally not regulated as dangerous goods for transport. Ship in well-sealed, labeled containers as general cargo, protected from moisture, heat, and direct sunlight. Follow the SDS, local regulations, and carrier requirements. |
| Storage | Store Acid Black 210 in a cool, dry, well-ventilated area away from direct sunlight and moisture. Keep containers tightly closed and labeled, and avoid generating dust. Separate from strong oxidizers, acids, bases, food, feed, and drinking water. Use appropriate secondary containment and follow the supplier’s SDS and local regulations. Store only in original or compatible containers. Ensure spill containment and employee training. |
| Shelf Life | Acid Black 210 typically has a 24-month shelf life when stored cool, dry, and protected from light and moisture. |
In a tannery wet-end unit running bovine wet-blue through a stainless steel drum with internal baffles and variable speed control, C.I. Acid Black 210 is introduced as a pre-dissolved aqueous solution to prevent grain specking. The dye is prepared at 70–80 °C at a concentration of 5–10% w/v, screened through a filter, and added to the drum after neutralization of the wet-blue to pH 5.5–6.0. The application range on shaved weight is 0.8–2.5% for medium to full black, with 2.5% reserved for upholstery leather requiring low reflectance and high opacity; lower dosages produce grey-black effects only on corrected-grain substrates. The dyeing float is held at 200–300% relative to wet-blue weight, temperature is raised to 50–60 °C, and the drum runs for 30–45 min before formic acid is added. Formic acid 85% is diluted 1:10 and dosed in two portions separated by 10–15 min to bring the final bath pH to 3.8–4.2; exhaustion is then continued for 20–25 min. The process conflict in production is anionic competition between the dye and synthetic fatliquoring agents: if the dye is added after anionic fatliquor, exhaustion drops sharply, and the spent bath carries visible colour. The dye is therefore added before the main fatliquor, or the fatliquor is split with 50% added after the dye has exhausted. Cationic retanning agents must not be applied before dyeing because they precipitate the dye at the grain surface and produce uneven black patches; they are applied only after fixation. Compliance for leather goods coloured with C.I. Acid Black 210 includes ISO 17075-1:2017 for hexavalent chromium, with a reporting threshold of 3 mg/kg; ISO 17234-1:2011 for restricted aromatic amines released from azo colorants, with a limit of 30 mg/kg per amine; and ISO 17226-1:2018 for formaldehyde. The relevant MRSL baseline is ZDHC MRSL V3.1 applied to leather chemicals and leather articles for automotive and upholstery customers. Drum practice on production floors shows batch-to-batch variance when wet-blue chrome content or shaving thickness is not normalized: higher chrome content accelerates dye uptake, and a thickness deviation above ±0.1 mm shifts the effective dosage relative to weight. Finished article types produced from this wet-end route include full-grain black automotive upholstery leather, corrected-grain shoe upper leather, and black leather goods such as watch straps and briefcases.
| Parameter | Test method | Typical acceptance threshold |
|---|---|---|
| Hexavalent chromium in leather | ISO 17075-1:2017 | <3 mg/kg |
| Restricted aromatic amines, leather | ISO 17234-1:2011 | ≤30 mg/kg per amine |
| Formaldehyde in leather | ISO 17226-1:2018 | Limit per OEKO-TEX LEATHER STANDARD; reference range ≤75 mg/kg for adult articles |
| Colour fastness to rub, leather | ISO 11640:2012 | ≥4 grey scale after 50 cycles |
| Light fastness, automotive leather | ISO 105-B02:2014 | ≥6 blue wool for automotive programmes |
Bath exhaustion on nylon 6.6 package-dyed yarn is governed by the concentration of free amino end groups, which varies with drawn yarn lot and heat-setting history. C.I. Acid Black 210 is dissolved at 1:10 in hot water before addition to the bath; the application ratio on weight of fibre is 0.5–2.0% owf for medium to deep black, with 2.0% typical for automotive seat fabric and door panel textile. The bath is set at pH 4.5–5.5 with acetic acid and sodium acetate, heated to 98 °C, and held for 30–45 min under reversible inward-outward flow in a package dyeing machine. Package density is controlled between 0.32 g/cm³ and 0.38 g/cm³; higher density creates pressure drop and uneven shade in inner package layers. The leveling agent is selected from weakly anionic or nonionic chemistries because strong cationic auxiliaries precipitate the dye and reduce light fastness. Production experience on polyamide 6.6 automotive yarn shows that draw-ratio variation and heat-setting temperature differences produce dye uptake differences known as barré; C.I. Acid Black 210 does not fully conceal barré on filament yarn, so fabric is normalized before dyeing by controlling spin-draw parameters and pre-scouring at 60–70 °C with a nonionic detergent. Compliance for automotive textile programmes includes ISO 105-B02:2014 for light fastness, ISO 105-C06:2010 for domestic and industrial washing, and ISO 105-X12:2016 for rubbing fastness. Automotive interior OEM specifications frequently require light fastness of at least 4 on the blue wool scale at 40 kJ or equivalent, but final acceptance is set by the vehicle manufacturer and may require higher ratings for seat cover textile. Restricted substance compliance is verified against ZDHC MRSL V3.1, and aromatic amine release is tested by EN 14362-1:2012 with a limit of 30 mg/kg per amine. Terminal finished products include woven and circular-knit nylon 6.6 seat cover fabric, door panel covering, and textile armrest/console cover stock.
Dyeing wool top, loose stock, and spinning yarn with a 1:2 metal-complex acid dye requires pH control closer to the isoelectric point of wool to limit tensile strength loss. The application ratio for C.I. Acid Black 210 on wool is 0.5–3.0% owf; full black wool for contract furnishing is typically dyed at 2.5–3.0%, while grey-black and charcoal shades require 0.5–1.5%. The dyebath is buffered with ammonium sulphate at 2–4% owf and acetic acid to pH 5.5–7.0, heated to 95–98 °C, and held for 45–60 min. The bath is then cooled at 0.5–1.0 °C/min to 60 °C before rinsing to prevent fibre embrittlement. In top dyeing machines and package dyeing vessels, liquor flow must be maintained without channelling; uneven packing in loose stock dyeing creates streamers of undyed fibre, so the vessel is loaded to a uniform density below the point where flow resistance triggers bypass. A production limitation is the lack of affinity of acid dyes for cellulosic fibres: in wool/cellulosic blended articles, the cotton component remains undyed and must be processed in a subsequent reactive dye bath, which increases total processing time by 60–90 min. C.I. Acid Black 210 does not require a chrome mordant because the metal is incorporated in the dye complex, which simplifies effluent handling relative to chrome dyeing. Compliance for wool technical textiles includes OEKO-TEX Standard 100 Annex 4 and end-use-specific limits for aromatic amines under EN 14362-1:2012, plus colour fastness verification under ISO 105-B02:2014 for light, ISO 105-C06:2010 for washing, and ISO 105-X12:2016 for rubbing. Terminal products dyed with C.I. Acid Black 210 in this route include wool upholstery cloth for contract interiors, black wool uniform fabric, and dense needle-punched felt for acoustic or thermal insulation.
Anodised aluminium that has been sulphuric-acid anodized presents a porous aluminium oxide layer in which C.I. Acid Black 210 is adsorbed before hot-water or nickel-salt sealing. The dye bath is prepared with deionized water at 2–10 g/L of C.I. Acid Black 210, adjusted to pH 4.5–5.5 with acetic acid and sodium acetate, and held at 50–60 °C; immersion time ranges from 5–15 min depending on anodic layer thickness and target black depth. Anodic film thickness for architectural profiles is usually 10–25 µm; films below 5 µm do not provide enough pore volume for saturated black and are more likely to show blotchiness. The anodizing process before dyeing is typically operated in 160–200 g/L sulphuric acid at 18–22 °C with a current density of 1.2–1.8 A/dm²; the workpiece is rinsed in deionized water immediately after anodizing to prevent pore closure. After dye adsorption, sealing is performed in hot water at 95–100 °C or in a 1–2 g/L nickel acetate bath at 85–90 °C to close the pores and lock the dye. Processing conflicts arise from phosphate or sulphate carryover into the dye bath, which shifts pH and reduces adsorption, and from organic contamination that causes uneven dye uptake on extruded profiles. The dye bath is filtered and its concentration checked spectrophotometrically at least once per shift; pH is adjusted only with dilute acetic acid. Compliance for anodized aluminium is verified by ISO 2143:2017 for sealing quality, ASTM B137-11 for coating mass, and ISO 105-B02:2014 for light fastness where exterior architectural exposure is specified. Terminal finished products include black anodized window and door profiles, curtain-wall trim, display hardware, and heat sinks requiring a black decorative/functional oxide layer.
At silk dyeing temperatures of 85–90 °C, the diffusion rate of a 1:2 metal-complex acid dye becomes the controlling variable when C.I. Acid Black 210 is evaluated as a replacement for sulphur black. The application ratio for silk piece goods and garments is 0.5–2.0% owf; deep black is usually approached at 1.5–2.0%, while lighter grey effects require 0.5–1.0%. The bath is set at pH 4.5–5.5 with acetic acid; mineral acids are avoided because pH below 4.0 reduces fibroin tensile strength and increases chafing marks in overflow and winch machines. Dyeing is run at 85–90 °C for 30–40 min, followed by cooling and rinsing. The process is sensitive to liquor ratio: garment dyeing at 1:15–1:20 liquor-to-goods ratio provides enough bath mobility for levelness, but very high liquor ratios increase acid consumption and reduce exhaustion. Production experience shows that C.I. Acid Black 210 has a lower strike rate than sulphur black at silk temperatures, which improves levelness but makes shade correction slower; a laboratory dyeing must be performed before bulk loading because published data for this specific configuration is limited. Compliance for dyed silk is verified under OEKO-TEX Standard 100 Annex 4, aromatic amine release under EN 14362-1:2012 with a limit of 30 mg/kg per amine, and colour fastness under ISO 105-B02:2014, ISO 105-C06:2010, and ISO 105-X12:2016. Terminal products include black silk neckwear, silk linings for tailored outerwear, silk scarves, and black silk sleepwear.
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Acid Black 210 is supplied under Colour Index designation C.I. Acid Black 210 and appears as CAS registry number 99576-15-5 on producer safety data sheets. The product is an acid dye of the metal-complex type sold as black to dark brown granules or powder and standardized to 100%, 150%, or 160% strength relative to a producer type standard. Its main applications are chrome-tanned leather drum exhaustion, spray finishing, polyamide exhaust dyeing, and decorative anodized aluminium coloration. The product is chosen when a bluish black tone and higher lightfastness are required and when excessive bronzing or high water-insoluble residue cannot be tolerated in the downstream process.
Incoming material is checked for moisture content, water-insoluble residue, pH, shade strength, and heavy metals before release. A 10 g/L dispersion in deionized water at 25°C is measured with a calibrated pH electrode; the common acceptance band is 6.5–9.5. Water-insoluble matter is determined gravimetrically after dissolution at 60°C and filtration through a 2.5 µm membrane. For spray finishing, residue above 0.2% by mass is rejected because it blocks air-assisted spray nozzles operated at 2.5–3.5 bar. Moisture by oven drying at 105°C to constant mass is normally held below 8.0%. Shade strength is measured spectrophotometrically in solution and is typically certified within ±3% relative to the producer’s retained standard. The certificate may also report CIELAB hue difference, with internal acceptance commonly set at ΔE ab ≤ 0.5. Free chromium(VI) in the dry powder is controlled below 3 mg/kg under ETAD code-of-practice limits where the product is destined for leather articles.
Manufacturer batch certificates usually express strength as percent relative to the type standard and include a CIELAB hue difference measured on a 0.1% solution in deionized water. Dyehouses with high-volume leather production retain a sealed reference powder and accept only batches with ΔE ab ≤ 0.5 against the reference. Powder dissolution is carried out by wetting with cold water to a paste, then diluting with water at 60–70°C under a high-shear impeller running at 800–1200 rpm for 15–20 min. Dry powder added directly into a drum at pH below 4.0 has produced localized specks on full grain cowhide in commission dyeing lots; the resulting defects require an additional levelling cycle with anionic surfactant at 55°C.
The metal-complex structure gives the product higher affinity for amphoteric leather sites than a metal-free acid black of similar sulfonation. Uptake is rapid between pH 4.0 and 5.0, slows between pH 5.5 and 6.0, and collapses above pH 6.5. In laboratory dyeing machines with controlled heating ramps, strike increases from 70°C to 95°C; this behaviour requires a levelling stage of 15–20 min before the main exhaust period. Phenol-sulfone syntans delay uptake by occupying the same cationic sites, whereas polycarboxylate retannages accelerate exhaustion and may destabilize levelness if drum speed drops below 10 rpm. A weakly cationic levelling agent at 0.5–1.0% on shaved weight is therefore introduced when the substrate has been retanned with strongly anionic syntans.
In drum exhaustion on chrome-tanned leather, the dye is added to a stainless steel drum with float 200–300% on shaved weight, bath temperature 50°C, and drum speed 12–16 rpm. The initial pH is buffered to 4.5–5.0 with acetic acid/sodium acetate. At 2.0% Acid Black 210 on shaved weight, the bath shows a visible black base within 45–60 min; transmission measurements at the bath-specific absorbance maximum indicate exhaustion above 92% before fixation. Fixation is completed by two additions of 0.5% formic acid 85% at 15 min intervals. In production lots, final exhaustion typically exceeds 98%. Dyed leather is subsequently tested for lightfastness according to ISO 105-B02; on chrome-retanned cowhide with a typical phenol-sulfone syntan retannage, a blue-scale rating of 4 to 5 is typical, but published data for a specific fatliquoring package are limited.
Water quality influences the product because moderately hard water above 20°dH can form calcium dye complexes when the bath is acidified below 5.0. In processing sites drawing groundwater at 25–35°dH, a polyacrylic acid sequestering agent at 0.5 g/L is added before dye addition. Without sequestration, the final leather may show haze on the grain and reduced wet rub fastness when tested according to ISO 105-X12.
Substitution is not a direct drop-in because Acid Black 210 produces a bluer black than Acid Black 194 on glutaraldehyde-retanned automotive crust. At 2.0% addition the difference is visible after fixation; at 3.5% addition the gap widens and requires reformulation of the shading dye. The product exhausts more rapidly in the weak-acid range. If the bath pH falls below 4.0, both dyes exhaust quickly, but Acid Black 210 can give lower colour uniformity on full grain cowhide when the drum speed is below 10 rpm. Production records from automotive leather lines show that a levelling period extension of 15–20 min is required when changing from Acid Black 194 to Acid Black 210. Fastness after fixation is checked under ISO 105-B02 and ISO 105-X12; wet rub fastness above grade 4 is achievable with a cationic fixing top spray, provided the leather is through-dried before fixing.
On a spray finishing line, the product is predissolved at 60–70°C and passed through a 100 µm stainless steel in-line screen before entering the spray reservoir. The solution is commonly prepared at 5–15 g/L dye concentration with a penetrating agent at 10–20% and a polyurethane or casein binder in the base coat. Air-assisted spray equipment with nozzle aperture 0.8–1.2 mm is set to a wet add-on of 80–120 g/m² on corrected grain; actual deposition depends on the absorbency of the crust. Spray finishing is used mainly to equalize shade differences from drum dyeing or to repair belly areas. Under CIE standard illuminant D65 in a light booth conforming to ISO 105-A01, the product gives less greenish artificial light reflection on corrected grain than C.I. Acid Black 234, although the comparison is made on production lots and is not a published instrument standard. Compared with C.I. Acid Black 52, Acid Black 210 builds deeper at 3% addition but has slower migration, so it is less suited to pastel shading. These differences are direction-specific; a changeover must be tested in the exact retannage and fatliquoring combination because the apparent shade difference can reverse when the crust contains high levels of phenolic syntan.
For polyamide 6,6 tricot beam dyeing at a liquor ratio of 1:20, the dyebath is set at pH 5.5–6.0 with monosodium phosphate/acetic acid. A temperature ramp of 1.0–1.5°C/min to 98°C is used, followed by a 45 min hold. The product shows high strike between 70°C and 95°C; a polyoxyethylene alkylamine equalizing agent at 0.5 g/L is used to slow initial uptake in beam equipment. After reductive clearing in alkaline hydrosulfite, wash fastness is evaluated according to ISO 105-C10; typical grey-scale ratings are 4 or higher on nylon 6,6 apparel, although published data for this specific beam configuration are limited. On nylon 6, the product exhausts similarly but may give slightly stronger depth at the same addition because of higher amino end-group availability. Beam machines with 1:15 liquor ratios require a prefiltered stock tank; commission dyeing records show that skipping this step results in package mark-off and internal shading variation in high-density packages.
For anodized aluminium, the dye bath is prepared at 10–20 g/L in deionized water, adjusted to pH 5.5–6.5, and held at 55–65°C. Sulphuric acid-anodized aluminium enters the bath after rinsing; tone depth develops within 20–40 min depending on oxide thickness and bath agitation. On high-production anodizing lines, the dye bath is filtered continuously through a 10 µm filter to remove precipitated aluminium hydrate and is maintained by conductivity-controlled water addition. The final L* value is sensitive to oxide thickness; a change from 12 µm to 18 µm oxide layer can deepen the black and require dye concentration adjustment from 20 g/L to 10 g/L. After coloration, the work is sealed in nickel acetate at 96–98°C for 30–40 min; the sealing bath pH is maintained at 5.5–6.0 and nickel concentration at 1.0–1.5 g/L to avoid bloom. Outdoor lightfastness of the sealed anodic coating is assessed by ISO 2135; architectural specifications may require a rating of 8 or higher. Published data for Acid Black 210 in this specific configuration are limited.
From a compliance standpoint, Acid Black 210 is subject to European REACH registration in the relevant tonnage band by the manufacturer or importer. Downstream leather users must ensure that finished articles meet the EU chromium(VI) limit of 3 mg/kg under REACH Annex XVII entry 47, measured by ISO 17075-2. The product is not intended as a direct dye for cellulosic fibres; it exhibits low substantivity on cotton and is not a substitute for reactive or sulfur blacks. Textile processors must request the producer’s certificate for restricted azo amines under REACH Annex XVII entry 43 if the product is used in textiles intended for skin contact. Spent dyebath treatment in leather effluent plants uses flocculation with ferric chloride at 100–200 mg/L and anionic polymer clarification; because the metal complex can bind in sludge, discharge permits require measurement of total chromium in the filterable fraction and not only chromium(VI).
Because the powder is hygroscopic, storage above relative humidity 60% causes compaction and lot-strength drift in tropical warehouses. Bags should be kept closed at 10–35°C and used within the producer-specified shelf life. The metal-complex chromophore is sensitive to strong reducing agents; a stripping bath containing sodium hydrosulfite at 60°C and pH 8.0–8.5 is safer than boiling reduction, which decomposes the chromophore and leaves a yellow-brown residue that is difficult to redye. Acid Black 210 must not be combined in one bath with cationic fixing agents because anionic-cationic precipitation occurs at neutral pH. In spray stock solutions, the pH should remain above 5.0; acidification below 4.0 can destabilize the concentrate and shorten usable pot life to less than 24 h. The product is not recommended for pure vegetable-tanned leather because the substrate has limited free cationic sites; exhaustion is poor and the resulting black is dull. In vegetable-chrome combination leather, a cationic pretreatment is required before Acid Black 210 is applied.
