Acid Red 18 also sold under names such as Ponceau 4R / New Coccine, is a water-soluble acid azo dye. It is widely used to color protein and polyamide fibers (wool, silk, nylon), and finds applications in inks, leather, paper, plastics and some industrial coatings. The dye absorbs in the visible red region (λmax ~506 nm) and is hygroscopic; like many acid dyes it is applied under acidic dyeing conditions and can require leveling or auxiliary agents for even shades.
eveling(grade) | Displacement | Whitening | Solubility(g/L) | Metal ion effect(grade) | ||
copper | iron | chromium | ||||
2~3 | — | well | 250(100℃) | 3~4D | 4Y | — |
Test Methods | fiber | Alkali resistance | Carbonization | Chlorination discoloration | Oxygen bleaching | potting | Alkali fluff color change | Acid fluff color change | Seawater discoloration | soaping | Perspiration | Sun exposure | |
discolor | Staining | ||||||||||||
AATCC | wool | 4 | 5 | — | 1 | 4~5 | 2 | — | 4 | 2 | 2 | 1 | 4 |
ISO | wool | 4 | 4~5 | 4 | 1~2 | 4~5 | 2 | 2~3 | 3 | 2 | 3~4 | 2 | 4 |
Mainly used for wool, silk, polyamide fiber and its blended fabric dyeing, also can be used for leather, paper, plastic, wood, medicine and cosmetics of dyeing, still can make the ink.
3. Acid Red 18 (Acid red 3R) dyeing fastness is poor, color brightness is not as good as acid red G, leveling is also poor, so it is rarely applied on textiles, generally replaced by other acid red.
Yes — Acid Red 18 is marketed under several synonyms including Ponceau 4R and New Coccine. Different suppliers may list slightly different registry numbers or purity grades, so always check the supplier specification sheet (SDS / CoA) for exact identity and purity before purchase.
Acid Red 18 is primarily an acid dye for protein and polyamide fibers — wool, silk and nylon are typical targets. It is also used in specialty inks, leather, paper and some plastics or coatings where water-soluble acid dyes are acceptable. For synthetic blends and non-polar substrates, dispersing agents or alternative dye classes may be required.
The dye is highly water-soluble and usually prepared as an aqueous stock; it dissolves readily with gentle heating and stirring. Avoid organic solvents for stock unless the supplier specifically recommends them — the dye is typically only slightly soluble in alcohols and insoluble in oils. Use dust control and PPE when making concentrated solutions.
Acid dyes in this class are applied under acidic conditions and are sensitive to liquor ratio, temperature ramp and electrolyte (salt/acid) dosing. For even shades, control pH, add the dye slowly at the recommended temperature profile, and consider leveling agents or levelling auxiliaries for high-shade depth or difficult substrates. (Exact recipe depends on fiber, machinery and scale.)
Acid Red 18 typically shows moderate light and wash fastness consistent with many acid azo dyes; performance depends strongly on fiber type, depth of shade and post-treatments. Where high fastness is required, test small batches and consider after-treatments or crosslinking/resin finishing if compatible.
Yes — Acid Red 18, like many synthetic dyes, can be persistent in water and is a focus of wastewater treatment research. Adsorption, advanced oxidation and other treatment methods are commonly studied to remove residual dye from effluent. Plan effluent controls and treatment for any process discharging dye-bearing wastewater.
Regulatory status varies by region and application. Historical safety reviews have examined its use in semi-permanent hair dyes and other formulations; always check the current regional regulations and any relevant safety opinions before using Acid Red 18 in cosmetics or food-contact applications. Consult the supplier’s regulatory documentation and local authorities.
Store in a cool, dry and dark place in tightly closed containers to limit moisture uptake (it can be hygroscopic). Use standard industrial hygiene practices: dust control, gloves and eye protection; follow the supplier SDS for spill response and disposal instructions.
