Acid Red 361 (C.I. 361, CAS 61931-22-4) is a red monoazo acid dye supplied as a water-soluble powder, formulated for dyeing protein and polyamide fibers (wool, silk, nylon) and used in textile, carpet and certain specialty ink/paint applications.
TRADE NAME:Acid Red 2B
Standard | Fiber | Soaping | Persperation Fastness | Oxygen bleaching | Light | |
Fading | Stain | |||||
ISO | Wool | 4-5 | 3-4 | 4-5 | 6 | |
Test Methods | fiber | Alkali resistance | Carbonization | Chlorination discoloration | potting | Alkali fluff | seawater | soaping | Perspiration color change | Sun exposure | |||
discolor | Staining | discolor | Staining | discolor | Staining | ||||||||
ISO | wool | 3~4 | 4 | 4~5 | 5 | 4~5 | 2~3 | 4~5 | 3 | 4~5 | 3~4 | 4~5 | 6 |
Fixing situation | soaping ISO105-C03 (60℃) | Alkali perspiration ISO105-E04 | Flooding ISO105-E01 | Chlorinated water ISO105-E03 | Sun exposure ISO105-B02 | |||||||
discolor | Nylon stain | Cotton stain | discolor | Nylon stain | Cotton stain | discolor | Nylon stain | Cotton stain | 100mg/L | Standard dye depth | ||
1/12 | 1/1 | |||||||||||
Unfixed | 4 | 4 | 4~5 | 4~5 | 3~4 | 4~5 | 4~5 | 4 | 4~5 | 4 | 5~6 | 6~7 |
Fixing | 4~5 | 4~5 | 5 | 5 | 4~5 | 5 | 4~5 | 5 | 5 | 4~5 | ||
Acid Red 361 shows strongest affinity and best leveling on nylon (polyamide) and protein fibers such as wool and silk. On nylon it often produces bright, even shades when dyed with an acid bath and controlled temperature rise; wool and silk also accept the dye well but may need different salt/acid dosing for optimal shade.
Typical starting recipe (lab-scale): liquor ratio 1:20–1:30, 1.0% OWF dye charge, 1–2% acetic acid to establish pH 4–5, raise temperature slowly to 85–95°C and hold 30–45 minutes, then cool and soaping if required. Always run small lab trials before production.
Performance depends on fiber and after-treatments: reported lightfastness is relatively high for an acid red, rubbing (wet/dry) is generally strong, while washfastness can be moderate — consider after-treatments (soaping, cationic fixing) to improve wash resistance.
Yes — some suppliers list Acid Red 361 for specialized inks or paint applications where water-soluble acid dyes are accepted. Compatibility depends on the carrier/resin system; perform formulation testing before scale use.
Acid dyes are water-soluble and will appear in effluent unless removed. Oxidative treatments such as ozone have been used successfully to remove Acid Red 361 from textile wastewater.
Store in a cool, dry area in sealed containers. Avoid inhalation and prolonged skin contact; use dust control and PPE. Consult the product MSDS for full HSE guidance.
