Section
| HS Code | 348924 |
| Product Name | Basic Magenta |
| Synonyms | Basic Fuchsin; Basic Violet 14; CI 42510; Rosaniline hydrochloride |
| Chemical Class | Triphenylmethane dye |
| Dye Class | Basic cationic dye |
| Color Index | CI 42510; Basic Violet 14 |
| Cas Number | 632-99-5 |
| Molecular Formula | C20H20ClN3 (rosaniline hydrochloride; mixture varies) |
| Molecular Weight | 337.85 g/mol (rosaniline hydrochloride; mixture varies) |
| Appearance | Dark green to dark red crystalline powder or crystals |
| Color | Magenta to deep red |
| Form | Powder or crystalline solid |
| Charge | Cationic |
| Solubility Water | Soluble in water, giving a magenta solution |
| Solubility Ethanol | Soluble in ethanol |
| Solubility Ether | Insoluble in ether |
| Absorption Maximum | Approximately 540-550 nm |
| Primary Use | Biological staining, Gram staining, acid-fast staining, Schiff reagent, textile dyeing |
| Storage | Store in a cool, dry, dark place in a tightly closed container |
| Hazard | Harmful if swallowed; may cause skin or eye irritation; suspected carcinogen/mutagen; handle with appropriate personal protective equipment |
As an accredited Basic Magenta factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Basic Magenta is packaged in a 25 g amber glass bottle with a tight screw cap and appropriate hazard labeling. |
| Container Loading (20′ FCL) | Basic Magenta packed in 25 kg bags on pallets, loaded into a clean, dry 20-foot FCL container, protected from moisture. |
| Shipping | Basic Magenta is generally not regulated as a dangerous good for transport. Ship it as a non-hazardous chemical in a sealed, light-resistant container with sturdy outer packaging and clear labels. Include the SDS, keep dry and away from oxidizers, and follow carrier/local rules. |
| Storage | Store Basic Magenta in a cool, dry, well-ventilated, secure area away from direct sunlight and ignition sources. Keep containers tightly closed and labeled. Segregate from strong oxidizers, acids, and bases. Use secondary containment to prevent spills, and keep away from food, drink, and animal feed. Wear appropriate PPE and dispose of waste according to local regulations. |
| Shelf Life | Stable if stored properly; typical shelf life is 2–5 years in a cool, dry, well-ventilated area away from light. |
For leather dyehouses, Basic Magenta (CI 42510, CAS 632-99-5) is handled as a water-soluble cationic triarylmethane dye with a narrow pH working window and limited lightfastness. In drum application on vegetable-retanned bovine side leather, the dye is pre-dissolved at a ratio of 1:20 in deionized water at 55–65 °C before introduction to a 800 kg stainless steel tannery drum. The substrate must be retanned with mimosa or chestnut extract and neutralized with sodium formate and sodium bicarbonate to a cross-section pH of 5.5–6.0; chrome-tanned wet-blue without retannage exhibits insufficient anionic fixation for Basic Magenta, causing low wet rub fastness measured by ISO 11640. Typical addition rates fall between 0.1% and 0.8% on shaved weight; split leathers for dark magenta require 0.5–0.8%, while garment lining shades use 0.1–0.3%. After dye addition, the drum runs for 40–60 min at 50–55 °C, then fixation proceeds by adding 85% formic acid diluted 1:10 over 20 min to a final float pH of 3.8–4.2. The terminal products are interior lining leather, bookbinding leather, decorative wallets, and craft leather goods; automotive upholstery and outdoor leather are excluded because Basic Magenta does not meet the lightfastness levels required by ISO 105-B02 for those applications. Effluent compliance is assessed under the European Union Industrial Emissions Directive and the ZDHC MRSL; the dye is not an azo compound and therefore does not generate the restricted arylamines listed in Annex XVII of REACH during standard reductive sweating tests.
Because the fibre contains anionic comonomer sites, exhaust dyeing of polyacrylonitrile fibre with Basic Magenta is governed by ion exchange rather than by fibre swelling alone. In package and hank dyeing machines, the dye bath is set at 60 °C with cationic retarder at 0.2–1.5% owf, 1–3 g/L acetic acid, and 0.5–1.0 g/L sodium acetate to hold pH at 4.5–5.0; retarder levels are raised at low liquor ratios below 1:15 to prevent rapid strike on the outer package layer. Basic Magenta is added at 0.2–1.5% owf for medium to deep red-violet shades on standard semi-dull acrylic; pale shades use 0.05–0.2% owf, and correction of shaded black lots may require only 0.01–0.05% owf. The bath is heated at 0.5–1.0 °C/min above 80 °C and held at 98–102 °C for 45–60 min; rapid heating through the glass transition region produces rope marks and package-to-package shade variation in 250–500 kg package dyeing machines.
| Stage | Parameter | Control range |
|---|---|---|
| Bath set | pH | 4.5–5.0 |
| Cationic retarder | on weight of fibre | 0.2–1.5% owf |
| Basic Magenta | on weight of fibre | 0.05–1.5% owf |
| Heating above 80 °C | rate | 0.5–1.0 °C/min |
| Hold | temperature/time | 98–102 °C for 45–60 min |
| Cooling | maximum rate | 0.7 °C/min |
On production-scale package dyeing machines, a common failure mode is a package density above 380 g/L; this increases differential pressure across the package and forces the dye to fix on outer yarn layers, producing ring dyeing visible after unwinding. Reversing pump direction every 2–3 min during the heating phase and limiting the heating rate above 80 °C to 0.5 °C/min reduces the defect. Because Basic Magenta has a relatively high strike rate on acrylic, the bath pH must not drift above 5.5; at pH 6.0 and above, the chromophore shifts toward a colourless carbinol form, reducing exhaustion and causing shade blueness in reprocessed batches. The terminal goods are usually indoor acrylic knitwear, chenille yarns for throws, and blankets; the dye is not recommended for automotive textiles because lightfastness measured by ISO 105-B02 is below the OEM minimum for exterior and glazing-adjacent parts. Compliance for the dyed textile is evaluated under OEKO-TEX Standard 100 and ZDHC MRSL Level 1 requirements for textile auxiliaries and dyes.
On high-speed tissue machines, stock dyeing with Basic Magenta uses the cationic charge of the dye to capture anionic fines, but the same mechanism can cause local dye aggregation if the furnish already contains high levels of anionic trash. The dye is metered as a 0.5–1.0% aqueous solution into the machine chest or directly into the fan pump suction at 0.005–0.2% on dry fiber for pastel to medium pink-magenta tissue; deeply colored poster grades use up to 0.3%. Wet-end pH is maintained at 4.5–6.0 with alum at 1–5 kg/ton of dry furnish, and a cationic polyacrylamide retention aid at 0.2–0.5 kg/ton is added after the colour to prevent two-sidedness on crescent former and high-speed tissue wire sections. After refining, stock passes to the machine chest and fan pump; the dye solution is injected through a static mixer before the headbox, with headbox consistency held at 0.1–0.3%. Terminal products include facial tissue, napkins, decorative wrapping paper, and non-food packaging board. Food-contact use requires migration testing under EN 646 and positive-list verification under the relevant national regulation; Basic Magenta’s water solubility precludes reasonable low-migration performance on uncoated paper.
In paste-type printing ink plants, Basic Magenta is converted to a run-resistant pigment by precipitation with phosphotungstomolybdic acid (PTMA) at controlled pH. The dye is dissolved in deionized water at 70–80 °C at 5–10% solids, and the PTMA solution is added over 30–60 min under high-shear dispersion; precipitant demand ranges from 1.2 to 1.5 parts by weight per part of dry dye. A Cowles disperser running at 1,500–2,000 rpm is used because slower addition without shear yields coarse 20–50 µm agglomerates that later clog bead mills and plate-and-frame filter cloths. The slurry is acidified to pH 4.0–4.5, filtered in a plate-and-frame press, washed until filtrate conductivity falls below 200 µS/cm, dried in a forced-air tray dryer at 70–80 °C, and pulverized to a top size of 10 µm through a pin mill.
| Variable | Control range |
|---|---|
| Dye solution concentration | 5–10% solids |
| PTMA-to-dye ratio | 1.2–1.5:1 |
| High-shear addition time | 30–60 min |
| Precipitation pH | 4.0–4.5 |
| Wash endpoint conductivity | below 200 µS/cm |
| Drying temperature | 70–80 °C |
| Milled top size | 10 µm |
The terminal products are interior-grade solvent-based flexographic and gravure inks, oil-based artist colors, and decorative coatings where high-humidity dry rub resistance is required. Compliance is documented by REACH and by pigment testing under ISO 787-9 for pH of aqueous suspension and ISO 787-7 for sieve residue; lightfastness remains the limiting property for exterior use, so application is confined to interior print and coating systems.
High-speed flexographic printing on kraft shopping bags and corrugated liner uses Basic Magenta as a soluble dye colorant when an aqueous ink must penetrate the substrate and dry by absorption rather than oxidation. The dye is predissolved in a water/ethanol blend at 40–50 °C, typically 80:20 water to ethanol, and then added to a styrene-acrylic or maleic resin varnish at 0.5–2.0% by weight of the finished ink. Ink pH is adjusted to 4.0–6.0; higher pH causes the triarylmethane chromophore to shift toward its carbinol form, reducing colour strength and causing shade drift during storage. On press, the anilox roll is specified at 200–360 LPI with cell volume 3.0–6.0 BCM to deposit sufficient dye without filling the screens; viscosity is held at 18–25 s on a Zahn cup #2. End products are paper carrier bags, newsprint inserts, wrapping tissue, and short-life decorative prints; because Basic Magenta has limited wet fastness, lamination or overprint varnish is required for any surface subject to moisture. Regulatory compliance follows REACH and the EuPIA exclusion list; direct or indirect food contact is excluded without a functional barrier validated under migration testing to the applicable EU regulation.
Dissolution of Basic Magenta for carbol fuchsin staining reagent manufacture begins with 0.3 g of dye per 10 mL of 95% ethanol, followed by dilution into 100 mL of 5% aqueous phenol. The sequence is not reversible; adding water before ethanol produces a partially insoluble tar-like residue that reduces staining intensity and blocks 0.45 µm membrane filters. Manufacture of ready-to-use Ziehl-Neelsen stain requires the ethanol solution to be mixed with the phenol solution at 20–25 °C, then held for 24 h before filtration to allow poorly soluble resinous impurities to aggregate. The filtered solution is filled into amber borosilicate bottles and labelled for in vitro diagnostic use. Compliance for European IVD products is structured under EU 2017/746, with quality management according to ISO 13485:2016; dye content is verified by UV-visible spectrophotometry against the certified absorbance maximum at 543–545 nm in dilute aqueous solution. Terminal products include carbol fuchsin staining kits, mycobacteriology laboratory reagents, and histology counterstain concentrates; industrial textile or paper use is excluded from this grade by the absence of processing auxiliaries and by heavier specification limits for insoluble matter. Published durability data for the staining solution at high ambient temperatures is limited; stability studies should be performed at 15–30 °C before assigning expiry intervals.
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Basic Magenta, designated C.I. Basic Violet 14 and CAS 632-99-5, is a cationic triarylmethane dyestuff supplied as dark green crystalline powder, press cake, or aqueous liquid concentrate. The principal coloured species in commercial product is the hydrochloride salt of rosaniline homologues, represented by C20H20ClN3 with molecular weight 337.85 g/mol; industrial lots contain related N-methylated homologues that alter solubility, exhaustion rate, and electrolyte sensitivity. A 0.1 g/L aqueous solution adjusted to pH 4.0 exhibits a visible absorption maximum within 543–546 nm when measured in a 10 mm quartz cuvette using a scanning UV-visible spectrophotometer. The dry powder is hygroscopic and requires storage at 5–30 °C and relative humidity below 60% in sealed fibre drums with polyethylene liners; caking occurs if ambient relative humidity exceeds 60% during transfer operations in unair-conditioned dye kitchens.
| Parameter | Test method or equipment | Typical control range |
|---|---|---|
| Dye content as C.I. Basic Violet 14 | Titanium trichloride reduction or UV-visible spectrophotometry | 85–90% for industrial powder; analytical grades may exceed 90% |
| Loss on drying | Oven at 105 °C to constant mass | ≤ 3.0% |
| Water-insoluble matter | Gravimetric after filtration through 2.5 µm membrane | ≤ 0.5% |
| pH of 1% aqueous solution | Calibrated pH meter with glass electrode | 3.0–5.0 |
| Absorption maximum in aqueous solution | UV-visible spectrophotometer, 10 mm quartz cuvette | 543–546 nm |
The dissolution behaviour of Basic Magenta in production dye kitchens is governed primarily by particle size, water temperature, and the presence of acid. In stainless steel or glass-lined mixing tanks with propeller agitation at 250–500 rpm, the powder is added slowly to deionized water maintained at 45 °C. The formulation temperature is kept below 60 °C because higher temperatures accelerate carbinol base formation under neutral or slightly alkaline pH and may produce tar-like deposits on vessel walls. If the powder is dumped into cold water below 30 °C, rapid hydration at the particle surface forms gel aggregates that resist dispersion and pass through filters only after prolonged agitation. A 10 g/L stock solution is usually dispersed within 20 min under these conditions; a 25 g/L stock may require 40–45 min and supplementary scraper agitation. Addition of 2–5% acetic acid by weight of the stock solution reduces aggregation and shortens the dissolution time, but acid addition above this range can reduce dye bath pH control when the stock is metered into an acrylic dyeing machine. Before use, the stock is passed through a 200 mesh stainless steel screen to remove undissolved gel species. Liquid grades are supplied at typical dye content between 20% and 50%; these minimise dust exposure and are preferred in automated dosing systems, but they settle on prolonged storage and require recirculation or drum rolling before sampling.
Commercial powder grades are not uniform across suppliers. Dye content expressed as C.I. Basic Violet 14 is commonly determined by titanous chloride reduction, and industrial powder lots are often standardised to 85–90%. Sodium chloride and sulphate are the principal diluents, which alter the net cation activity and the mass addition required to reach target colour depth. Loss on drying at 105 °C to constant mass is typically controlled below 3.0%; water-insoluble matter is controlled below 0.5% when measured gravimetrically. These values are lot-dependent and should not replace the certificate of analysis for a specific purchase. No universal model number exists across suppliers; product designations such as Basic Magenta Crystals, Basic Magenta Powder 100%, and Basic Magenta Liquid are commercial descriptors rather than standardised chemical models.
In histochemical staining, Basic Magenta functions as the chromophore in carbol fuchsin formulations and in Schiff reagent. A standard working formulation for acid-fast staining is prepared by dissolving 1 g of Basic Magenta in 10 mL of 95% ethanol and adding 100 mL of 5% aqueous phenol; the mixture is filtered after standing and applied under mild heat or steam. Because staining intensity depends on phenol purity and dye homologue distribution, laboratories validate each new lot against positive control slides before routine use. In Schiff reagent, Basic Magenta is decolourised with sulphur dioxide to form the leucosulphonic acid intermediate; the magenta colour redevelops at aldehyde sites after acid hydrolysis of tissue sections. The reagent is stored at 2–8 °C in amber glass bottles, and colour development is sensitive to residual oxidant and exposure to light. Feulgen staining protocols require hydrolysis in 1 M hydrochloric acid at 60 °C; the hydrolysis time is tissue-specific and must be calibrated with each batch of reagent.
For acrylic fibre dyeing, the dyebath is buffered to pH 4.5–5.5 with acetic acid/sodium acetate. Exhaustion is performed in soft-flow overflow machines at a liquor ratio of 1:15 to 1:20; the bath is ramped to 98 °C at 1 °C/min and held for 45–60 min. During this hold, the cationic dye exhausts onto anionic sites in the fibre. Once fixation occurs, migration is limited, so leveling auxiliaries that provide temporary complexation are added for pale depths and package dyeing. Fastness is evaluated according to ISO 105-C10:2006 for washing and ISO 105-B02:2014 for light; values for Basic Magenta on acrylic are shade-dependent and generally below those achieved with high-lightfast basic dyes on the same substrate. Dyehouse operators control batch-to-batch shade variation by pre-dispersing each lot in 10% acetic acid at 50 °C and metering the stock into the side tank over 20 min. This procedure is used on soft-flow machines to minimise shade difference caused by rapid initial strike.
In paper shade control, Basic Magenta is applied as a dilute aqueous solution at addition levels of 0.001–0.050% on dry fibre. Retention on bleached kraft is improved by adding cationic polyacrylamide and alum at pH 4.5–5.0; without retention aid, a significant fraction of the dye remains in white water and causes shade drift during long runs. Dosing pumps with static mixers are preferred over batch dumping because hydraulic residence time in the stock approach system is short. At addition rates above 0.05%, the hue shifts toward blue-edged magenta and effluent colour may exceed mill discharge permits unless tertiary treatment is installed.
| Colourant | C.I. designation | Charge class | CAS | Visible absorption maximum in water | Primary process limitation |
|---|---|---|---|---|---|
| Basic Magenta | C.I. Basic Violet 14 | Cationic triarylmethane | 632-99-5 | 543–546 nm | pH above 8.0 causes carbinol base fading and reduced chromophore intensity |
| Basic Red 9 / Pararosaniline | C.I. 42500 | Cationic triarylmethane | 569-61-9 | 545 nm | Lower solubility in cold ethanol than Basic Magenta |
| Basic Violet 10 / Rhodamine B | C.I. 45170 | Cationic xanthene | 81-88-9 | 554 nm | Fluorescent; unsuitable where non-fluorescent staining is required |
| Acid Fuchsin | C.I. Acid Violet 19 | Anionic triarylmethane | 3244-88-0 | 540–550 nm | Precipitates with cationic auxiliaries and cationic dyes |
Basic Magenta differs from Basic Red 9 principally by N-methyl substitution on the triarylmethane skeleton. Basic Red 9, CAS 569-61-9, is pararosaniline and lacks the methyl groups that give Basic Magenta its shifted solubility and electrolyte sensitivity. In Schiff reagent, substitution of Basic Red 9 for Basic Magenta changes the intensity of fuchsine-sulphurous acid staining because the leuco form of pararosaniline has different reoxidation kinetics and aldehyde sensitivity. In acrylic dyeing, Basic Magenta may exhaust at lower temperature than Basic Red 9 but shows greater sensitivity to hydrolysis in alkaline after-rinse conditions. Replacement in production is performed on an equal molar basis rather than equal mass because the molecular weight of the dye base differs. Published data for this specific substitution in production dyehouses is limited; therefore, side-by-side trials using a multi-cell laboratory dyeing machine are recommended before bulk replacement.
Basic Magenta is cationic and therefore incompatible with anionic levelling agents, sulfated auxiliaries, and lignosulfonate dispersants in the same bath. Contact between concentrated Basic Magenta solution and anionic products produces immediate dye-dye precipitation, which appears as filtration spots and shade loss. Cleaning protocols using caustic and reducing agents must remove residual Basic Magenta before acid dyeing in the same vessel. Unlike pigment magenta preparations based on quinacridone such as Pigment Red 122, Basic Magenta is water-soluble and is not retained in plastics without mordant; it also lacks the heat stability required for polyolefin masterbatch extrusion at 220–230 °C. In printing inks, Basic Magenta provides high colour strength at low concentration in low-viscosity flexographic and stamp-pad formulations, but lightfastness is poor and documents stored in direct sunlight may exhibit visible fade within one summer in aggressive climates.
Regulatory classification is governed by Commission Regulation (EU) No 231/2012 for food colourants, under which Basic Magenta is not listed as a permitted food colour. In the European Union, the product is subject to Classification, Labelling and Packaging obligations and requires a safety data sheet. REACH registration duty lies with the EU importer or manufacturer. Because the product contains aromatic amino functions, waste discharge to biological treatment should be controlled to avoid shock load; colour removal may require oxidative or adsorptive tertiary treatment depending on local permit. Safety data sheets and lot-specific certificates of analysis should be consulted before the product is introduced into a new dyehouse or laboratory workflow.
