Direct Fast Turquoise Blue GL is supplied as the sodium salt of a sulfonated copper phthalocyanine chromophore and is indexed as C.I. Direct Blue 86. The model code “GL” identifies a greenish turquoise shade within the supplier’s range; it is a commercial designation and should not replace the Colour Index classification on safety data sheets or regulatory documents. Commercial formulations are standardized in powder and low-dust granular presentations. Bulk density varies between 600 and 850 kg/m³; moisture content is controlled below 80 g/kg, and water-insoluble matter is typically limited to 2 g/kg or less. The pH of a 10 g/L aqueous solution is commonly 6.0–9.0. Colour strength is determined spectrophotometrically in deionized water against a retained reference batch, with strength tolerance around ±5%. The absorption maximum falls in the red region of the visible spectrum, so dilution curves and strength checks use the red absorbance channel of the spectrophotometer. The active dye content is not a fixed universal value; sodium sulfate or dextrin is used as the standardizing agent, and the exact content is stated on the certificate of analysis. The anionic sulfonate groups provide substantivity for cellulosic textiles, bleached pulp, and chrome-tanned leather. The copper phthalocyanine macrocycle contributes high light fastness and a bright turquoise hue, but it also introduces copper into the wastewater profile.

Which Electrolyte Profile Keeps Exhaustion Uniform in High Liquor Ratio Jig Dyeing?

Direct dye exhaustion on cotton is governed principally by electrolyte screening of the negative charge repulsion between the sulfonated dye and the cellulosic fibre surface. In jig dyeing at liquor ratios from 5:1 to 10:1, sodium chloride is added at 10–40 g/L for medium depths; sodium sulfate may replace sodium chloride at 15–60 g/L when chloride-induced corrosion of stainless steel equipment is a concern. The dyebath is set at 40–50 °C, and the dissolved dye is added over 10–15 min. The first salt portion is introduced only after 5–10 min of circulation. Temperature is then raised at 1.0–1.5 °C/min to 90–95 °C and held for 30–45 min. Rapid salt addition or an initial temperature above 60 °C causes unlevel dyeing because the phthalocyanine molecule aggregates readily and has limited migration once exhausted. On production jigs with 1200 mm batch diameters, end-to-end shade variation can exceed 0.5 CMC units if the heating ramp exceeds 2 °C/min. After dyeing, the fabric is cooled to 60 °C before sampling and rinsing. Laboratory dyeing machines such as the Ahiba IR or Mathis Labomat reproduce these conditions when the liquor ratio and salt addition profile are matched to production.

In package dyeing of viscose yarn, the flow path rather than the salt profile controls levelness. Beams are packed at densities between 0.28 and 0.35 kg/L. The dye solution is pre-filtered through 25 μm bag filters before addition, and pump flow is maintained at 1.5–2.5 m³/h per kg of yarn. Pressure drop across the package should remain below 1.0 bar; higher values indicate dye aggregation or fibre swelling. Pump reversal at 2–4 min intervals reduces inside-to-outside shade variation. The temperature rise is held at 1 °C/min to 85–90 °C, and salt is added in three portions after the bath has reached 70 °C. If hard water exceeds 150 mg/L CaCO₃, polyphosphate sequestration is used before dye dissolution to avoid calcium-dye precipitates that plug yarn layers. This type of batch-to-batch flow variation is a common production bottleneck when the product is first introduced into package dyehouses.

On continuous pad-steam equipment, Direct Fast Turquoise Blue GL is padded at 60–80% expression on a two-bowl or three-bowl padder and steamed at 102–105 °C for 60–90 s. Because no alkali is required, the dye shows less tailing than reactive turquoise, but unbound dye can migrate during intermediate drying. Cylinder surface temperature is kept below 100 °C, and the distance between padder and first drying cylinder is limited to 3 m to reduce migration. A cationic fixing agent is then padded at 2–5 g/L active solids and pH 6–7. No curing step is needed; cold rinsing removes unfixed dye and salt. Pilot trials on a 30 m/min pad-steam range with 25 μm bag filters before the dye trough have shown acceptable shade reproducibility, although published data for high-speed chainless mercerizing ranges combined with this specific colorant is limited.

Differential Fastness and Migration Kinetics in C.I. Direct Blue 86 Versus Reactive Turquoise

The process difference between Direct Fast Turquoise Blue GL and reactive turquoise colorants such as C.I. Reactive Blue 21 is fixation chemistry. Direct dye exhausts through adsorption, aggregation, and salt-induced substantivity, while reactive turquoise forms a covalent bond with cellulose under alkaline conditions. Wet fastness is therefore the limiting property for direct dyeings; aftertreatment with a cationic fixing agent is generally required to bring washing fastness into an acceptable range under ISO 105-C06:2010. Reactive turquoise retains colour through multiple wash cycles without aftertreatment, but its alkali window is narrower and hydrolyzed dye must be removed by washing at 70–90 °C. Light fastness is evaluated by ISO 105-B02:2014; copper phthalocyanine direct dyes typically perform better than many azo direct dyes. The migration kinetics also differ: Direct Fast Turquoise Blue GL has moderate migration at 90–95 °C, while reactive turquoise has minimal migration after fixing. Table 1 summarizes the process-level differences.

In paper wet-end coloration, the dye is added to thick stock at 0.5–1.5% on dry fibre for pastel to medium turquoise shades. Alum addition after dye contact at 5–10 kg/tonne dry fibre improves retention. Calcium hardness above 150 mg/L CaCO₃ can precipitate the sulfonated dye as a calcium salt and produce specks; polyphosphate or demineralized water dissolution is required. The dye solution should be screened through a 100 μm filter before the fan pump. Cationic retention aids added before the dye reduce uptake because they occupy anionic sites. White-water residual colour is minimized at pH 4.5–6.0. At size press addition, the dye is combined with starch or polyvinyl alcohol at 2–5 g/L; this route gives brighter surfaces but lower wet-end retention and requires the size press solution to be filtered to prevent streaks.

On chrome-tanned leather, Direct Fast Turquoise Blue GL is applied as a crust dye from a bath at 40–55 °C and pH 4.0–5.0. The copper phthalocyanine chromophore yields bright turquoise shades with less bronzing than many basic dyes. A typical drum liquor ratio is 1:10 to 1:15; dye is added over 15 min and drumming continues for 30–45 min. Before fatliquoring, the float pH is raised to 5.5–6.5 to improve fixation. Direct dye interacts with cationic fatliquors if both are present in the same float; separate floats are preferred. Shade dulling may occur when the dye contacts vegetable retanning agents, and published data for this specific combination is limited. A preliminary beaker trial is recommended when retanning chemicals contain condensed tannins or sulfone syntans.

When Hard Water, Cationic Fixatives, or Polyacrylonitrile Blends Are Present

Direct Fast Turquoise Blue GL forms insoluble complexes with strong cationic agents in the same bath. Cationic fixing agents are applied only as a separate aftertreatment. Water hardness above 150 mg/L CaCO₃ should be controlled with EDTA, polyphosphate, or a sulfonate-compatible chelating agent before dye dissolution. The product has no substantivity for polyacrylonitrile or unmodified polyester; polyester-cotton blends require separate polyester and direct cotton dyeing cycles because the dye will not exhaust on polyester. Chlorine-based oxidants cause shade loss in the copper phthalocyanine chromophore, so laundering with chlorine bleaches is not recommended. Under REACH Annex XVII Entry 43, the product should not release restricted arylamines. Copper-bearing effluent must be treated by precipitation at pH 8–10 with lime or sodium hydroxide; residual copper limits depend on discharge permits. Material safety data sheets specify local exhaust ventilation during weighing and transfer to reduce dust exposure, and dust masks with N95 or FFP2 filtration are typical for handling concentrated powder.

Storage stability is governed by moisture pickup and temperature. Sealed bags should be stored below 40 °C and protected from relative humidity above 65%. In humid environments, partially used bags should be resealed immediately to keep moisture below 80 g/kg; compacted product dissolves more slowly. Stock solutions at 5–20 g/L in demineralized water remain free of visible precipitation for 48 h at 25 °C when pH is held between 6.0 and 9.0. In hard water, stock solution stability drops and a sequestrant is required. For warehouse inventory, stock rotation should follow first-expiry-first-out because dye strength can drift slightly over extended storage; retained samples are checked by spectrophotometry every 12 months against the original standard.

Quality control laboratories typically measure colour strength by UV-visible spectrophotometry after dissolving the sample in demineralized water and filtering through a 0.45 μm membrane. Test methods for fastness are selected according to the final article: ISO 105-C06:2010 for domestic washing, ISO 105-E01:2013 for water, ISO 105-E04:2013 for perspiration, and ISO 105-B02:2014 for artificial light. In textile dyehouse release testing, the dye is compared with a retained reference on mercerized cotton at 1/1 standard depth and checked for unequal levelness under D65 illumination. Batch-to-batch variance in low-dust granular production arises mainly from spray dryer atomizer speed and agglomeration temperature; these are controlled to maintain colour strength within ±5% and moisture below 80 g/kg.