Dye Classes, Suitable Fibres and Important Characteristics
Different dye classes are suitable for different fibres because each fibre has its own chemical structure and dye affinity. A dye that works well on wool may not work well on polyester; a dye suitable for cotton may not be suitable for acrylic or nylon. Therefore, the selection of dye class depends first on the fibre to be dyed and then on the required shade, fastness, cost, and end use.
The following table gives a useful comparison of important dye classes, the fibres on which they are commonly used, and their important characteristics such as brightness, washing fastness, light fastness, perspiration fastness, crocking behaviour, and special limitations.
| Dye Class | Fibres | Important Characteristics |
|---|---|---|
| Acid Dyes | Protein fibres, nylon, spandex, and special types of acid-dyeable acrylic. | Produce bright colours. Most are not fast to washing. Fastness varies from poor to good. Fastness to light and perspiration varies. They generally have excellent fastness to dry cleaning. |
| Premetalized Acid Dyes | Same as above. | Less bright than acid dyes, but have better fastness to laundering, perspiration, and light. |
| Chrome Dyes also called mordant dyes |
Same as above. | Produce dull colours, but have excellent fastness to light, washing, and perspiration. They are widely used on wool for covering. |
| Cationic Dyes also called basic dyes |
Acrylic, modacrylic, cationic-dyeable polyester, cationic-dyeable nylon. Also used on cellulosic and protein fibres. | Produce bright shades with excellent fastness to light, washing, and perspiration. Crocking may occur on man-made fibres. They have very poor fastness to washing and light on cellulosic and protein fibres. |
| Direct Dyes also called substantive dyes |
Cellulosic fibres. | Poor fastness to washing. Fastness to light varies, but some are excellent and are used in dyeing drapery and upholstery. Fastness to perspiration and dry cleaning is good to excellent. |
| Direct Developed Dyes | Same as above. | Same as direct dyes, except that washing fastness is good to excellent. |
| Disperse Dyes | Acetate, acrylic, modacrylic, nylon, polyester, and olefin. | Washing fastness varies with the fibre. It is poor on acetate and excellent on polyester. Fastness to perspiration, crocking, and dry cleaning is good to excellent. Light fastness is fair to good. Gas fading can occur on acetate, especially with blues and violets. This fading results from exposure to nitrous oxide, a gas pollutant in the air. Gas fading inhibitors are sometimes used in conjunction with dyeing and finishing processes, but they offer only temporary relief. |
| Disperse Developed Dyes | Same as above. | Same properties as above. Mostly dark blues and black shades. |
| Naphthol Dyes also called azoic, insoluble azo, ice, or ingrain dyes |
Cellulosic fibres. | Produce bright shades, mostly deep reds, yellows, and oranges. Light fastness varies from poor to excellent. Fastness to washing and perspiration is good to excellent. Heavy shades may have poor fastness to crocking. |
| Reactive Dyes | Mostly cellulosic fibres. Also used to a lesser degree on protein fibres and nylon. | Produce bright shades. Generally good to excellent fastness to light, laundering, perspiration, and crocking. They have poor fastness to chlorine. They are difficult to dye with when attaining close shade matching. |
| Sulfur Dyes | Cellulosic fibres. | Produce dull shades, predominantly navy, black, and brown. They have excellent fastness to light, washing, and perspiration, but poor fastness to chlorine. Some sulfur dyes may cause tendering, or weakening of fabric, if stored for greater lengths of time. |
| Vat Dyes | Same as above. | Mostly excellent fastness to light, washing, and perspiration. They are exceedingly fast to chlorine and other oxidising bleaches. They may crock if improperly applied. |
| Pigments | All fibres. Applied to fabric only as solid colour or print. | Pigments are not true dyes. They are mechanically bound to the fibre by resins. Heavy shades tend to stiffen the fabric. Light to medium shades mostly have excellent light fastness and fair to good fastness to hand laundering. Medium to heavy shades have poor fastness to crocking. |
How to Read This Table
The table shows that dye selection is always connected with fibre selection. Cellulosic fibres such as cotton, rayon and linen can be dyed with direct, reactive, sulfur, vat and naphthol dyes. Protein fibres such as wool and silk are commonly dyed with acid, premetalized acid and chrome dyes. Polyester is mainly dyed with disperse dyes, while acrylic is commonly dyed with cationic or basic dyes.
The table also shows that brightness and fastness do not always go together. Some dyes give very bright colours but poor washing fastness. Some dyes give duller shades but much better fastness. For example, chrome dyes are less brilliant but have excellent fastness, while acid dyes are bright but may not always be fast to washing. This is why dyeing is always a balance between colour brilliance, cost, fibre compatibility and end-use performance.
Important Terms Used in the Table
Fastness means the resistance of colour to different agencies such as washing, light, perspiration, rubbing, dry cleaning or bleaching. A dye with good washing fastness does not easily lose colour during laundering. A dye with good light fastness does not fade quickly in sunlight.
Crocking means the transfer of colour from the dyed fabric surface to another surface by rubbing. A fabric may look well dyed, but if it crocks badly, it can stain the wearer’s skin, another garment, upholstery or accessories.
Tendering means weakening of the fabric. Some sulfur dyes may cause tendering when fabric is stored for long periods, especially if improper processing or after-treatment has taken place.
Conclusion
The choice of dye class is one of the most important decisions in textile colouration. The dyer must consider the fibre, the required shade, expected brightness, washing fastness, light fastness, rubbing fastness, chlorine resistance, cost and final use of the textile. A beautiful colour is not enough; it must also remain suitable during use, washing, exposure and handling.
Therefore, textile dyeing should be understood not merely as colouring cloth, but as matching the right dye chemistry with the right fibre and the right performance requirement.
References
- CottonWorks. Textile Dyeing. Cotton Incorporated. https://www.cottonworks.com/wp-content/uploads/2018/01/Dyeing_Booklet.pdf
- Aspland, J. R. Textile Dyeing and Coloration. American Association of Textile Chemists and Colorists, 1997. https://books.google.com/books/about/Textile_Dyeing_and_Coloration.html?id=5fMBJZ8NPcgC
- Trotman, E. R. Dyeing and Chemical Technology of Textile Fibres. Charles Griffin & Company. https://archive.org/details/dyeingchemicalte0000trot
- Clark, M. (ed.). Handbook of Textile and Industrial Dyeing: Principles, Processes and Types of Dyes. Woodhead Publishing, 2011. https://www.sciencedirect.com/book/9781845696955/handbook-of-textile-and-industrial-dyeing
- Gulrajani, M. L. Fundamentals and Practices in Colouration of Textiles. Woodhead Publishing India, 2010. https://www.sciencedirect.com/book/9781845697884/fundamentals-and-practices-in-colouration-of-textiles
- Shenai, V. A. Chemistry of Dyes and Principles of Dyeing. Sevak Publications. https://lan-portal.uob.edu.ly/link/PPT/9783T4I009/chemistry-of_dyes__and__principle-of-dyeing_by_v-a_shenai.pdf
- Benkhaya, S., M’rabet, S., & El Harfi, A. Classifications, Properties, Recent Synthesis and Applications of Azo Dyes. Heliyon, 2020. https://www.sciencedirect.com/science/article/pii/S2405844020300042
- Pandit, P., Singha, K., Maity, S., & Ahmed, S. (eds.). Textile Dyes and Pigments: A Green Chemistry Approach. Wiley/Scrivener, 2022. https://scrivenerpublishing.com/cart/title.php?id=747
- Encyclopaedia Britannica. Pigment. https://www.britannica.com/technology/pigment
- INFLIBNET Centre. Textile Colouration / Dyeing and Printing. https://epgp.inflibnet.ac.in/
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