Acid Blue Black 10B (C.I. Acid Black 1, C.I. 20470, CAS 1064-48-8, molecular weight 616.49 g/mol) is a disazo acid dye supplied as sodium salt. The following application entries are restricted to sectors where the dye is demonstrably used: protein fiber exhaust dyeing, polyamide continuous and exhaust dyeing, leather drum dyeing, anodized aluminum coloration, paper decoration, and biochemical protein detection. Each entry records the governing standard, the addition ratio, the production process, and the terminal article class.

In top dyeing and hank dyeing of wool, Acid Blue Black 10B is exhausted from a pH-controlled aqueous bath onto the fiber surface and into the cuticle–cortex boundary. The anionic sulfonate groups of C.I. Acid Black 1 require protonated amino sites on the wool polypeptide chain; bath pH is therefore held between 3.8 and 4.5 with formic acid or an acid donor. Deep navy-black shades on wool tops are typically built with 2.5–3.0 % owf dye, while mid-grey and slate tones are matched at 0.2–0.8 % owf; silk hank dyeing uses 1.5–2.5 % owf to avoid surface scouring and luster loss. Exhaustion is carried out in package dyeing machines, top dyeing autoclaves, or hank dyeing vats at a liquor ratio of 1:10 to 1:20. The recommended ramp profile starts at 40 °C, increases at 1–2 °C/min to 98 °C, and holds for 45–60 min. Mill water hardness above 150 ppm CaCO₃ suppresses strike and shifts the solid shade blue-red in production lots; a chelating agent based on EDTA or polyphosphate is added to the bath before dye dissolution. The dye must not be premixed with cationic leveling agents because electrostatic precipitation forms filter-blocking particles in package machines. After exhaustion, the bath is dropped at 70–80 °C, and wet fastness is improved with a cationic dye-fixing agent applied at 40–60 °C for 20 min in a fresh bath. Compliance for wool and silk articles is normally verified against ISO 105-C06 for domestic washing, ISO 105-E04 for perspiration, and ISO 105-B02 for light fastness; OEKO-TEX Standard 100 Annex 4 applies to finished textile certification, while REACH registration and ZDHC MRSL v3.1 conformance are required for the dye as a chemical input. Terminal articles include wool suiting, scarves, costume fabrics, dyed top for mélange yarn, and silk lining materials. The operational boundary is the aggregation threshold: application above 3.0 % owf on untreated wool produces bronzing and poor wet-rub resistance, and the resulting shade cannot be corrected by extending the boil because the dye redissolves unevenly.

What Explains the Shift in Wet Pickup When Nylon 6.6 Fabric Is Dyed at 4.5 % owf?

Continuous pad-steam ranges for polyamide 6.6 woven and warp-knit fabric typically operate at a wet pickup of 60–70 % after nip pressure adjustment; the dye concentration in the pad trough is set at 10–25 g/L for black and navy work. For beam and jig exhaust dyeing, addition levels of 2.0–4.0 % owf are used because nylon 6.6 has fewer amino end-groups than wool and saturates more readily. The pad liquor is buffered to pH 4.5–5.5 with acetic acid and includes 20–50 g/L migration inhibitor or anti-frosting agent to control barré in warp-knits. After padding, the goods are steamed at 102–105 °C for 20–30 min or fixed by dry heat at 170–180 °C for 60–90 s; the steam route gives better wet fastness but can cause shade variation across the roll if condensate drips. Fastness is assessed by ISO 105-C06, ISO 105-X12 for rubbing, and AATCC 61 2A where U.S. retail protocols control. Chemical input compliance follows REACH registration, ZDHC MRSL v3.1, and the finished fabric is certified under OEKO-TEX Standard 100 if required. The terminal articles are swimwear, lingerie, athletic mesh, lining, and automotive interior fabrics where light fastness requirements do not exceed ISO 105-B02 rating 5. The main process conflict is end-group variation: nylon 6.6 with lower amine end-group content can show 20–30 % lower dye yield at the same dyebath pH; dyeing above 4.0 % owf does not compensate because unfixed dye creates crocking risk. A pre-scour at 60 °C with nonionic detergent and soda ash is required when mill knits contain more than 0.5 % spin finish.

If pH Falls Below 3.8 During Leather Drum Dyeing, What Happens to Grain Coverage?

Leather drum dyeing with Acid Blue Black 10B is constrained by the timing of fatliquor addition and the rate of formic acid fixation. On shaved wet-blue, the dye is added at 1.5–4.0 % of shaved wet-blue weight in a float of 100–200 % at 50–60 °C; the drum is run for 20–30 min before fatliquor is introduced, because anionic fatliquors compete for cationic sites and reduce dye uptake. pH is initially adjusted to 4.5–5.0 with ammonium formate or sodium acetate, and fixation is completed by adding diluted formic acid in two doses to pH 3.6–3.8. If pH falls below 3.8, the sulfonated dye strikes the grain surface so rapidly that through-penetration is blocked; the crust leather then shows pale cut edges and uneven sanding after buffing. The standard test set includes ISO 11640 for rubbing fastness, ISO 11641 for washing fastness, and ISO 105-B02 for light fastness where the article is exposed to moderate daylight. Because of the azo structure, textile and leather buyers routinely request REACH Annex XVII entry 43 amine screening data and ISO 17234-1 or EN 14362-1 test reports for the dye lot; ZDHC MRSL v3.1 conformance is required for the chemical formulation. Terminal products are footwear upper crust leather, belt leather, bag leather, and split suede for dark casual goods. The material is not specified for automotive seating where high lightfastness and migration resistance are mandatory; acid dye migration into topcoat under heat ageing remains a known limitation.

On architectural aluminum anodizing lines, Acid Blue Black 10B is dissolved in a pH-buffered dye bath after sulfuric acid anodizing and before hot sealing. The working bath is prepared by dissolving 0.5–2.0 g/L dye in demineralized water at 60–70 °C, cooling to 50–60 °C, and adjusting pH to 4.5–5.5 with sodium acetate or dilute acetic acid. The anodic coating is produced in sulfuric acid at 15–20 V DC, with a coating thickness of 10–25 µm for exterior architectural profiles; after anodizing, the work is rinsed twice to remove sulfate ions that otherwise precipitate dye at the pore mouth. Dwell time in the dye bath is 10–20 min depending on depth of shade; longer immersion yields a blue-black surface but does not significantly improve dye penetration beyond the outer 5–8 µm of the porous oxide. Sealing is carried out in hot nickel acetate or nickel-free hot water at 90–95 °C for 15–25 min; seal quality is commonly tested by ASTM B136-84 or ISO 2143 acid dissolution. The relevant anodizing specification is MIL-A-8625F Type II for sulfuric acid coatings, with RoHS 2011/65/EU applicable to electronic enclosures and REACH for the dye bath input. Terminal articles include black architectural extrusions, solar panel frames, automotive interior trim, and consumer electronics housings. Operational boundaries are narrow: bath pH below 4.5 increases dye aggregation and creates a surface haze that is not removed by sealing; pH above 5.5 slows uptake and shifts the oxide coloration to grey-blue. Published data for this specific dye in Type II anodic coatings is limited, so the stated 0.5–2.0 g/L starting point should be confirmed by colorimetric reflectance measurement against a sealed production coupon.

Paper Beater Dyeing Retention Limits at 40 °SR

Addition to thick stock at refining degree 40 °SR shifts the dye uptake mechanism from direct adsorption to retention-aided complexation. In beater dyeing, Acid Blue Black 10B is added at 0.05–0.5 % on bone-dry fiber after refining; the stock pH is held at 4.5–5.5 with alum, because anionic dye retention on cellulose is poor at neutral pH. A cationic polyamine or poly-DADMAC retention aid is dosed at 0.02–0.1 % on dry fiber after dye addition, followed by mixing for 10–15 min before sheet formation. In surface dyeing, the dye is formulated at 0.5–2.0 g/L in a starch or polyvinyl alcohol size press solution and applied at 60–70 °C; the process is used only for non-food decorative grades because Acid Blue Black 10B is not cleared under FDA 21 CFR 176.170 for direct food-contact paper. The governing compliance framework includes REACH for the supplied dye, EU 1935/2004 for food-contact exclusion testing where converters request migration screening, and EN 71-3 for heavy metal migration in toy and stationery paper. Terminal products are colored stationery, file dividers, decorative tissue, board for packaging, and menu covers. The main process boundary is lightfastness: Acid Blue Black 10B on uncoated paper degrades under prolonged UV exposure and is unsuitable for archival or outdoor poster stock. Two-sidedness is controlled by maintaining headbox consistency above 0.8 % and avoiding over-flocculation from excess cationic additive.

Electrophoretic Protein Staining Formulation Boundaries

For SDS-PAGE and nitrocellulose membrane work, Amido Black 10B staining solutions are prepared at 0.1 % w/v dye in 10 % v/v acetic acid and 25 % v/v isopropanol; a destaining solution of 10 % v/v acetic acid with 25 % v/v isopropanol removes unbound dye without excessive band fading. Stain time for 1.0 mm polyacrylamide gels is 30–60 min with gentle agitation; nitrocellulose membranes require 2–5 min for visual protein detection and longer destain times only where low-abundance bands are not recorded. The process is not regulated under textile or leather standards; for laboratory supply, the relevant compliance is REACH Article 31 safety data sheet availability, CLP classification, and institutional chemical hygiene protocols. Published data for this specific configuration is limited because staining protocols vary by acrylamide concentration and fixation chemistry. Fixed gels are first immersed in 40 % methanol/10 % acetic acid for 30 min to prevent diffusion; the stain is then applied without heating, because temperatures above 40 °C increase destaining interference and weaken band contrast. Terminal outputs are analytical results: protein bands on gels, membrane-bound proteins for densitometry, and laboratory documentation, not manufactured consumer articles. Dye lot-to-lot tinctorial strength should be normalized by staining a known protein standard at 0.15 µg/lane and measuring optical density at 620 nm.