Introduction
As we sport a range of textiles on a daily basis, how often are we struck by the thought of how fabrics retain the colour once imparted after all the washes they go through? Rubbing fastness is a critical parameter in textile manufacturing that determines how clothes behave after treatment with dyes of different colours and concentrations.
In the course of a fabric’s use, it undergoes several mechanical stresses and friction that can cause dye transfer or fading. This property is particularly important in industries producing high-end garments, upholstery, and technical textiles where colour durability is a key quality factor.
Manufacturers rely on standardised testing methods and speciality textile finishing chemicals to enhance colour retention and minimise dye migration. Let us understand how rubbing fastness works and the factors influencing it; it is a stepping stone for manufacturing long-lasting, high-quality textiles that meet industry standards.
Understanding Rubbing Fastness: Definition and Testing Methods
The term Rubbing Fastness originates from the testing method used to evaluate the colour fastness of textiles. Referring to the action of gently rubbing a textile sample against another material to simulate wear & tear, this procedure is a measure of the fabric’s ability to resist colour change or bleeding. In textile processing, these tests assess and analyse the amount of colour transferred under dry and wet rubbing conditions. Microscopic study reveals any damage or loose dye particles, testing the material’s durability and the impact of friction on their surface.
This property is crucial in ensuring that textiles maintain their aesthetic appeal and not stain other materials during use. Standardised tests are employed to assess rubbing fastness, with the Crock meter being a commonly used instrument, whether hand-driven or motorised. Two fabric specimens are prepared for the test to evaluate the degree of colour transfer. One is passed through the dry test (under controlled pressure and motion), and the other, after soaking and squeezing, is subjected to cyclic rubbing motions.
The testing apparatus, consisting of metre scales like the Gray Scale for Staining or the Chromatic Transference Scale, measures the degree of colour transfer after abrasion resistance testing and colourfastness grading. Readings above 5 indicate superior colour fastness and values lower than that are proof of tangible colour bleeding mishaps.
Key Factors Influencing Rubbing Fastness in Textiles
As we tune into the finer details of rubbing colour fastness in textiles made of various gradients of fibres, we need to consider factors before making analytical assumptions regarding the pros and cons of colour impact, longevity and durability in clothes. Below are listed some of the indispensable parameters that govern textile processing and leave a lasting impression on fabrics we use daily:
- Material Characteristics: The quality of fibres or yarns and the surface structure of the fabric significantly impact rubbing fastness. For instance, smoother surfaces tend to have better resistance to colour transfer.
- Dye Selection and Depth of Shade: The type of dye and the intensity of the colour applied can affect fastness. Darker shades often show lower rubbing fastness due to higher dye concentration.
- Dyeing and Printing Techniques: Proper fixation of dyes during these processes is crucial. Unfixed dyes are more likely to transfer during rubbing.
- Textile Chemicals & Surface Finish: Softening agents and other finishing chemicals can enhance the fabric’s resistance to abrasion and improve overall fastness.
- Environmental Conditions: Factors like moisture can exacerbate colour transfer, making wet rubbing fastness a key consideration.
Textile Chemicals That Improve Rubbing Fastness
Chromatic development or colour build-up on fabrics can be accentuated if textiles are pre-treated with certain chemicals or processed with finishing additives after the colour fastness test.
Specialised fixatives, crosslinking agents, and polymer-based coatings help strengthen dye-fibre bonding, minimising dye bleeding. Cationic fixing agents improve the interaction between anionic dyes and textile fibres, particularly for reactive and direct dyes. Silicone softeners and resin-based finishes create a protective layer on fabric surfaces, reducing friction and preventing pigment detachment. Additionally, Nano-coatings and Fluoro-chemical treatments enhance fabric durability while maintaining colour integrity.
Textile pre-treatment and finishing additives enhance rubbing fastness by modifying fibre-dye interactions at a molecular level. Fixatives, often cationic, form electrostatic bonds with anionic dye molecules, anchoring them firmly to the fibre. Crosslinking agents create covalent bonds between dye and fibre, reducing dye migration. Silicone and resin-based finishes act as hydrophobic barriers, limiting friction-induced dye loss. Nano-coatings enhance surface smoothness, minimising mechanical abrasion.
Best Practices to Enhance Textile Processing
Enhancing textile processing requires innovative techniques, efficient resource management, and sustainable practices. The future of the Indian textile industry rests on optimised production processes, careful investment in advanced technology, an unwavering focus on quality control, adopting sustainable practices, and improving supply chain management. Hopefully, the below-listed information helps:
| Best Practice | Benefits |
| Optimised Pre-Treatment | Enhances dye penetration, uniformity, and fastness. |
| pH Control in Dyeing | Reduces dye wastage, improves colour consistency. |
| Use of Fixatives & Binders | Improves colour fastness, reduces rubbing & washing off. |
| Controlled Drying & Curing | Prevents dye degradation, enhances fastness properties. |
| Efficient Water Management | Reduces environmental impact, lowers production costs. |
| Application of Softener & Lubricant | Improves hand feel, minimises surface damage. |
| Nano and Advanced Coatings | Provides stain resistance, better wear & tear resistance. |
| Eco-friendly Processing | Reduces energy consumption, supports green manufacturing. |
FAQs
- What is the purpose of rubbing fastness testing in textiles?
- Rubbing Fastness testing evaluates a textile’s ability to resist colour transfer or bleeding when subjected to rubbing or friction.
- Can rubbing fastness vary depending on the type of dyeing pigment used?
- Yes, the type of dye or pigment used can significantly impact the Rubbing Fastness of a textile. For example, fibre-reactive dyes tend to have better Rubbing Fastness than direct dyes.
- What type of fabrics give a higher reading in the Crock meter and which fabrics exhibit lower values?
- Fibres like cotton, linen and rayon have a high affinity towards absorbing dyes, hence give readings >5. Fabrics like polyester, nylon and acrylic have moderate colour fastness, giving readings 4-5. Fibres like silk, wool & spandex exhibit colour bleeding issues, with values 1-4.
- Can rub fastness be improved after textile production?
- Yes, rubbing fastness can be improved after textiles are processed through post-treatment processes, such as applying dye fixatives or fabric finishes.
- Why is Rubbing Fastness important for textile manufacturers and consumers?
- It is crucial for ensuring the durability and quality of textiles, as well as preventing colour transfer or bleeding that can damage other fabrics or skin.
Sources:
- https://www.hohenstein-academy.com/en/e-learning-videos/seminar-detail/show/video-tutorial-rub-fastness# .
- https://www.orientbag.net/post/2016/09/26/color-fastness-to-crockingrubbing-test-iso-105-x12-with-video
- https://www.researchgate.net/publication/340560955_Study_on_Test_of_Color_Fastness_to_Rubbing_of_Textiles
- https://www.mdpi.com/2313-433X/9/11/251
- https://pmc.ncbi.nlm.nih.gov/articles/PMC8537305/