Abstract Achieving high colour depth while reducing dye consumption poses a significant challenge in textile finishing. This study introduces a synergistic strategy to enhance the apparent colour depth of polyester fabrics by creating a low‐refractive‐index surface film, thereby improving the K/S value of black polyester fabrics. Two distinct dual‐bath application sequences were compared: Process II, which involves a polyurethane (PU) pre‐coating with 10 wt% PU followed by a 20 wt% cationic fluorosilicone (COFS) finish, outperformed both Process I (reverse sequence) and the single‐bath COFS method. Specifically, Process II achieved a 34.8% increase in K/S value, surpassing the 29.7% maximum enhancement observed in the single‐bath control. The treated fabrics demonstrated excellent colour fastness, rated at Grade 4 for washing (GB/T 3921‐2008) and Grade 4 for rubbing (GB/T 3920‐2008). Scanning electron microscope (SEM) analysis confirmed the formation of a smooth, uniform coating on the fibre surface, suggesting enhanced light‐trapping capability. Notably, the PU/COFS bilayer architecture enabled a significant reduction in dye usage compared to conventional methods, while maintaining a soft handle and superior durability. This work presents a viable approach towards achieving ultra‐deep‐coloured polyester textiles.
Abstract Regenerated bamboo fibres offer a sustainable alternative to conventional cellulosic materials; however, achieving high and reproducible colour strength with reactive dyes may depend on both fibre accessibility and dye molecular architecture. This study comparatively evaluated the influence of reactive dye structure on the coloration performance of caustic‐treated regenerated bamboo fabrics. Eight commercial reactive dyes representing different chromophore classes and reactive‐group chemistries were investigated using a three‐stage experimental design to (i) select an appropriate sodium hydroxide concentration, (ii) evaluate bath configuration and (iii) compare dye‐dependent colorimetric responses under the selected conditions. An sodium hydroxide concentration of 8°Bé provided the most favourable balance between whiteness, colour‐strength enhancement and bursting‐strength retention. Depending on the dye, caustic treatment increased K / S by approximately 6%–50%. The magnitude of improvement varied with chromophore architecture, approximate molecular bulk, reactive‐group functionality, substantivity and dye‐specific application conditions. Scanning electron microscopy (SEM), X‐ray diffraction (XRD) and Fourier transform infrared (FTIR) results were consistent with alkali‐induced surface modification, hydrogen‐bond rearrangement, structural relaxation and reduced apparent crystalline order without evidence of cellulose derivatisation or a major polymorphic transformation. Relative unlevelness index measurements showed that the caustic‐treated fabrics exhibited excellent within‐specimen colour uniformity. Fastness results indicated that the increased colour strength was durably retained under the applied wash, rubbing, perspiration, water and light‐fastness tests. The findings demonstrate that the effectiveness of caustic‐assisted dyeing of regenerated bamboo fabrics is dye‐specific and governed by the combined influence of substrate modification, dye molecular architecture and processing conditions.
Abstract Over time, denim fabrics have transformed from being used as hard‐wearing clothing items to being applied in numerous areas of the world as part of fashion, hence the need for environmentally friendly color fading methods. This research presents a comparative analysis of chromatic parameters and physical properties of denim fabric treated with manual and laser whiskering techniques. The key objective is to evaluate differences in surface appearance, color fading effects developed by both treatments. Chromatic parameters were assessed using CIE L *, a *, b * values, chromaticity ( C *), hue angle ( h °) and color strength ( K / S ). Physical properties included dimensional stability in warp and weft directions, and tensile strength. Color fastness was evaluated against washing, rubbing and perspiration. Significant differences were found for K / S , C * and R % values through statistical analysis with one‐way ANOVA, but no significant difference was found for hue angle, CIE L *, a *, b * values, tensile strength, areal density and dimensional stability ( p > 0.05). The analytical findings revealed that the laser whiskering method produced higher color strength ( K / S ), chromaticity and reflectance values than the manual whiskering method, indicating better color retention and more vivid color characteristics. The laser‐treated fabrics also exhibited slightly higher tensile strength and lower shrinkage%, demonstrating improved dimensional stability. Regarding color fastness, the laser whiskering method showed comparable performance in washing, rubbing and perspiration tests to the manual process. The fabric's areal density remained almost unchanged between the two treatments. The laser whiskering process provided superior fabric performance while maintaining desirable color fading and physical properties.
Abstract To reduce the dye uptake rate of cationic dyes on polyacrylonitrile (PAN) microfibers and achieve uniform dyeing results, synthetic double‐headed quaternary ammonium salts (BTAE‐12) and quadruple‐headed quaternary ammonium salts (PTAE‐12) were used as retarding agents. These were compared with the conventional retarding agent dodecyl dimethyl benzyl ammonium chloride (1227). The differences in exhaustion percentage of methylene blue‐dyed PAN microfibers were compared across three concentrations of the retarding agents. The regulatory effects of the retarding agents on the methylene blue uptake rate and dyeing transition temperature during the heating stage were investigated, and their influence on the dyeing kinetics of PAN microfibers was analysed. Results indicate that BTAE‐12 and PTAE‐12 exhibit superior retarding effects compared to 1227, with PTAE‐12 demonstrating better performance than BTAE‐12. Without compromising the final dye exhaustion percentage, the optimal concentrations for achieving the best retarding effects were approximately 0.4 mmol/L for 1227, 0.15 mmol/L for BTAE‐12 and 0.025 mmol/L for PTAE‐12. As the retarding agent concentration increased, the dyeing transition temperature gradually rose. As the number of quaternary ammonium cation groups in the dye‐retarding agent molecules increased, the dyeing rate constant gradually decreased, extending the time required to reach equilibrium.
This study investigates the natural dyeing potential and comprehensive GCMS profiling of green husk of wild-growing western Himalayan walnut (Juglans regia L.) for textile applications. The phytochemical analysis revealed high phenolic content (181.7 +/- 1.5 mg GAE/g) and flavonoid content (77.4 +/- 2.1 mg CE/g) along with carbohydrates (62.4 +/- 1.8 mg/g), moisture (5.2 +/- 1.0%) and ash content (18.4 +/- 1.8%). FTIR analysis indicated the presence of phenolic O-H stretches, carbonyl groups and aromatic C-H bonds. GCMS profiling identified several phytochemical constituents contributing to dye performance. The dye extract exhibited antioxidant activity (85.4%) with an IC50 value of 20 mu g/mL. Cotton fabric dyed with and without mordant (alum, iron sulphate) demonstrates good to excellent fastness grades (4, 5), colour strength ranging from 3.8 to 4.2 with highest depth obtained using iron sulphate compared to un-mordanted fabric, lightness (L) ranging from 60.6 to 74.9, hue shifts (h degrees) around 80-82 degrees depending on mordant type. The dyed fabric also showed excellent ultraviolet protection (UPF 50+). These results indicate the potential of green husk of wild-growing western Himalayan walnut as a sustainable and less environmentally harmful dye alternative for the industrial sector.
Abstract The rapid growth of global trade has led to a significant rise in counterfeit goods, posing a serious risk to the safety of product circulation. This situation necessitates the urgent development of advanced intelligent anti‐counterfeiting technologies that can respond at multiple levels. Carbon dots (CDs), which are fluorescent nanomaterials measuring less than 10 nm, possess adjustable luminescence properties, are environmentally friendly and have excellent biocompatibility, making them a promising alternative to traditional anti‐counterfeiting methods. This paper provides a comprehensive review of the recent progress in single, double and multicolour CDs used in anti‐counterfeiting inks over the last 4 years. It examines technological advancements from static marking to intelligent interactive security systems and emphasises the design strategies and various applications for creating dynamically responsive invisible inks and intelligent information encryption systems. The paper discusses the synergistic effects of various factors, including quantum confinement, surface defect‐state radiative transitions and enhanced emission through intramolecular and intermolecular cross‐linking. It also summarises the impact of dynamic regulation mechanisms, such as solvent polarity affecting Stokes shift, concentration‐dependent aggregation‐induced luminescence changes and pH‐responsive excited‐state proton transfer, on the multi‐dimensional representation of anti‐counterfeiting information. Finally, the paper identifies existing challenges and potential solutions while highlighting the significant promise of CDs in the realm of anti‐counterfeiting inks.
Abstract Garment dyeing is becoming one of the most significant coloration processes due to its advantages, such as versatility, ability to fulfil the fashion needs swiftly and lower inventories. This review focuses on current issues in the coloration technology, processes and recent developments of garment dyeing, with special attention paid to reactive dyeing, over‐dyeing, pigment coloration, tie‐dyeing and garment tinting. The main findings suggest that reactive dyeing is still one of the leading methods in dyeing cellulosic garments, although it is highly sensitive to pH, electrolytes and temperature. The pigment coloration method offers great substrate flexibility. On the other hand, over‐dyeing proves effective in adjusting shades and covering up faults. Tie‐dyeing and tinting prove effective for creating variations in aesthetic appeal, using variability in the processes involved. From a review of the available studies, it becomes apparent that recipe optimisation is a crucial factor while ensuring consistency in shade production. However, slight variations in recipe can cause defects like uneven dyeing, shading and variation in shades produced. Future research should emphasise recipe optimisation by using artificial intelligence, sustainable dyeing methods and process monitoring in garment dyeing technology.
Abstract Mercury contamination remains a serious environmental and public health concern because of its extreme toxicity, persistence and bioaccumulation in living systems. The demand for rapid, sensitive and selective detection has driven significant research into chemosensors as practical alternatives to conventional analytical methods. This review provides a concise overview of the recent developments (2015–2025) in colorimetric and fluorometric chemosensors for Hg 2+ detection. It focuses on organic molecular probes, such as rhodamine, coumarin, and Schiff base derivatives, as well as emerging nanomaterial‐based systems. The underlying sensing mechanisms, including chelation‐enhanced fluorescence (CHEF), photoinduced electron transfer (PET) and intramolecular charge transfer (ICT), are discussed in detail in this review. The comparative performance of these sensors is evaluated with respect to selectivity, sensitivity, detection limits and practical applicability. Many sensors have demonstrated nanomolar detection limits and reliable performance in real samples. This review highlights the progress in portable test strips and intracellular imaging, and presents the challenges and opportunities for developing improved sensors for environmental and biological mercury monitoring.
Spray techniques have gained widespread applications in denim garment dry processes for obtaining controlled fading and vintage effects in terms of colours. The impacts of chemical sprays on the chromatic and physical properties of the denim fabric need to be analysed before optimising the process. In this research, the effect of an oxidative potassium permanganate (KMnO4) spray and calcium hypochlorite [Ca(OCl)2] as well as alkaline sprays comprising sodium hydroxide (NaOH), potassium hydroxide (KOH), and calcium hydroxide [Ca(OH)2] spray treatment on indigo-dyed denim fabric samples at concentrations of 5, 10 and 15 g/L has been analysed. The effect of chemical spray treatments on factors such as chromaticity, L*, reflectance % (R%) and warp shrinkage was found to be statistically significant using one-way ANOVA test, while that on tensile strength and areal density was statistically insignificant. The KMnO4 spray treatment resulted in a significant colour-fading effect but caused comparatively more structural change in fabric because of the oxidising nature of KMnO4. The NaOH and KOH sprays resulted in good performance with reasonable strength retention and vintage effect on denim surface, and the Ca(OCl)2 spray yielded acceptable results regarding visual colour-faded properties along with structural changes. Of all the spray treatments, the Ca(OH)2 spray showed optimum performance. This research can assist while improving denim garment dry processes as KMnO4 spraying may be preferred when strong colour fading and worn-out effect are required, while alkaline spraying may be preferred when moderate colour fading is required along with optimum properties.
Abstract Azo‐pyridone dyes are attractive candidates for high‐performance color filters owing to their rigid conjugated frameworks and high thermal stability. However, their practical application is often limited by strong intermolecular interactions that promote aggregation, resulting in broadened absorption profiles and compromised optical quality in thin films. Herein, we demonstrate that introducing N‐heterocyclic substituents, morpholine and pyridine, onto the azo‐pyridone core effectively disrupts π–π stacking and suppresses aggregation, enabling uniform dye dispersion in poly(methyl methacrylate) (PMMA) matrices. The resulting dye‐PMMA composite films exhibit high optical transmittance (>90%), significantly improved yellow color purity and excellent thermal and photostability (Δ E < 3). Combined experimental and density functional theory (DFT) analyses reveal that the heterocyclic substituents modulate the molecular electrostatic potential distribution and reduce intermolecular interaction strength, accounting for the suppressed aggregation behaviour. Both morpholine and pyridine proved effective, confirming the generality of this substitution strategy. This work provides a practical molecular design approach based on N‐heterocyclic modification for developing high‐performance azo‐pyridone dyes for advanced color filter applications.
Hydrophobic functional finishing is highly sought after in the textile industry to impart protective properties while preserving breathability and wearing comfort. Developing high-performance, eco-friendly fluorine-free durable water repellents (DWRs) has become a critical industrial imperative. Herein, various fluorine-free water repellents were systematically investigated and applied to cotton fabrics. Emulsion characterisation revealed that these agents are strongly cationic, facilitating robust electrostatic adhesion to negatively charged cotton fibres. The highly cationic emulsions with smaller particle size and narrow distribution facilitate stronger electrostatic adsorption and more uniform film formation, which significantly enhances washing and abrasion resistance. Moreover, cationic fluorine-free systems exhibit superior interfacial affinity towards negatively charged cotton fibres compared with conventional systems, providing an intrinsic mechanism for durability. Their low polydispersity index indicated high monodispersity, which promoted the formation of a uniform micro-nanoscale rough coating on the fibre surfaces. Under optimised processing conditions, the finished cotton fabrics exhibited superior hydrophobicity with high static water contact angles. The whiteness value of the untreated woven cotton fabric is approximately 95. After finishing, the fabrics largely retain their original whiteness, indicating that the treatment has only a limited effect on their wearability. Although air permeability experienced a slight reduction (10%-30%) due to physical pore blockage and structural rearrangement, the fabrics maintained excellent breathability. Additionally, the treated fabrics demonstrated outstanding anti-fouling performance against common household liquids, alongside robust mechanical and washing durability. This work provides theoretical insights and practical pathways for replacing hazardous fluorinated chemicals with sustainable fluorine-free systems.
Vat photopolymerisation (VPP) has become a pivotal technology in dentistry, offering precise fabrication of photosensitive resins for various applications. However, the colour stability of these materials remains a critical challenge, directly influencing their aesthetic and functional performance. This review systematically examines the colour stability of VPP‐based resins, detailing methodologies for colour characterisation and measurement, including visual thresholds and International Organisation for Standardisation (ISO) standards. Comparative analyses highlight differences between VPP‐based resins and other manufacturing methods, such as milling, which often demonstrate superior colour stability. Key factors affecting colour stability, including staining mediums, cleaning protocols, resin composition, and 3D printing parameters, are thoroughly explored, supported by findings from in vivo studies. Despite advancements, inconsistencies in results and the lack of consensus on clinically acceptable colour thresholds emphasise the need for further research. Promising developments, such as hydrophobic monomers and optimised printing parameters, offer potential improvements. This review provides evidence‐based insights to guide the enhancement of long‐term aesthetic and functional performance in dental materials produced via VPP.
Dyeing cotton with natural dyes typically requires the pre-application of a mordant, which enables better dye exhaustion from solution and 'fixes' the colorant in the fibre. The most common application system for cellulosic fibres is a combination of plant-derived tannins and aluminium salts, such as aluminium sulphate. However, a recognised commercial deficiency of this mordanting process is the relatively poor exhaustion of the aluminium from the mordanting bath into the fibre leading to a discharge of metal salts into the environment, and in addition, the subsequent exhaustion of the dye into the metal mordanted cotton is similarly incomplete. This study reports for the first time on an improved commercial and craft process based on the pre-application of the novel ECOFAST (TM) Pure cationic fixing agent to cotton to impart better natural colorant dyeing characteristics and minimise environmental impact. The pre-modification of the cotton with ECOFAST (TM) Pure, at 5%-10% on weight of fabric, increased the cochineal dye exhaustion up to similar to 99%, a significant increase from the similar to 62% dye exhaustion observed with the tannic acid/alum pre-mordanted cotton fabric. Lower temperature dyeing of the ECOFAST (TM) Pure modified cotton at 60 degrees C also resulted in improved dye exhaustion and colour strength relative to the traditional tannic acid/alum mordanted cotton. The incorporation of a levelling agent, Matexil DA-AC, into the dyebath formulation improved the dye levelness, decreased the dye exhaustion, but also unexpectedly increased the colour strength of the dyed fabrics at the 2% on weight of fabric (o.w.f.) levelling agent application level.
Disperse dyes are virtually insoluble in water, necessitating the addition of substantial quantities of dispersants and extensive grinding to produce commercially viable dyes suitable for polyester fabric dyeing. In this study, a series of 2,4-bis(4-sulfonylanilino)-1,3,5-triazin-6-yl starch ethers (BSATS) with varying molecular weights were prepared through non-directive sulfonation of acid-degraded starch in an aqueous medium for application as disperse dye dispersants. The dispersing performance and underlying mechanisms of these dispersants were analysed. The results showed that the BSATS series of dispersants exhibited superior dispersing ability for disperse dyes. Compared with the commercial dispersant NNO (dye filtration time 68 s after treatment, dispersibility rating C, particle size change 68% after high temperature treatment), the dispersants BSATS 3-7 with molecular weights ranging from 13.2 & times; 104 to 21.0 & times; 104 g-mol-1 showed superior dispersibility (dispersibility rating B) and thermal stability (particle size change only 12% after high temperature treatment). Additionally, the BSATS dispersants were employed to disperse C.I. Disperse Orange 30 primary dyes, yielding uniformly dispersed dye liquors for polyester fabric dyeing. In terms of dyeing performance, the dye suspension containing BSATS dispersant achieved a dye uptake of 90% and colour fastness grades of 4-5. This study presents a methodology for the preparation of starch-based high-performance dye dispersants, thereby expanding the efficient utilisation of biomass starch in the printing and dyeing industry.
The spectral analysis of multi-component dye systems faces challenges due to overlapping absorption bands and nonlinear effects, making it difficult to accurately characterise individual components and predict their concentrations. To address this, the study proposes a Kernel-based Multivariate Curve Resolution (Kernel-MCR) model combined with Multiple Linear Regression (MLR) for high-precision spectral separation and concentration prediction. Mixed samples of a ternary dye solution were prepared using an orthogonal experimental design, and their spectra were recorded. After preprocessing, the Kernel-MCR method achieved component spectral separation, and MLR modelled the concentrations using the resolved relative concentration matrix. Performance was evaluated using Spectral Angle Mapper (SAM), Pearson Correlation Coefficient (PCC), coefficient of determination (R 2) and Root Mean Square Error (RMSE). The results showed that Kernel-MCR effectively resolved overlapping spectra, with SAM angles below 15 degrees between separated component spectra and true spectra. The MLR modelling method combined with Kernel-MCR significantly outperforms traditional modelling approaches, effectively addressing issues such as spectral overlap. The R 2 for predicting the concentration of each component has improved to over 0.98, while the Root Mean Square Error (RMSE) has been reduced by more than 37%, validating the accuracy and robustness of this method. This method enhances multi-component dye analysis, offering a reliable solution for intelligent detection in printing and dyeing processes.
Re-evaluation using the Williams-Landel-Ferry (WLF) equation, of diffusion coefficient and standard affinity data previously reported for five different disperse dyes within/onto three different types of esterified cellulose substrate, reveals that thermally activated dye diffusion/adsorption adheres to a WLF relationship and is therefore governed by the thermally regulated structural relaxation times of the respective water-saturated, water-swollen, water-plasticised cellulose acetate or cellulose triacetate macromolecule over the broad 40 degrees C to similar to 100 degrees C range of dyeing temperatures considered. The plasticisation model of dye diffusion appears to offer a reasonable explanation of the pronounced temperature dependency of the diffusivity of the various disperse dyes within the different types of cellulose ester substrate.
The instability of anthocyanins limits their application as natural food colorants. This study aimed to enhance the stability of anthocyanins extracted from Hibiscus sabdariffa through copigmentation with protein nanofibrils produced from pea, rice, gluten and whey isolates. Linear and curly nanofibril structures were prepared and incorporated into yoghurt and soft candy to evaluate anthocyanin and color stability during refrigerated and ambient storage, respectively. In yoghurt, copigmentation with curly protein nanofibrils resulted in the highest anthocyanin retention and the most stable red color during storage, whereas linear nanofibrils provided more limited protection. Changes in color characteristics indicated that curly nanofibrils were more effective in preserving the red hue and color quality. In soft candy, samples containing copigmented anthocyanins showed significantly lower anthocyanin degradation and improved color stability compared with both natural and synthetic control colorants. Although a gradual reduction in color saturation was observed in all formulations during storage, copigmented systems-particularly those containing curly nanofibrils-exhibited slower color deterioration. The results demonstrate that protein nanofibrils, especially curly structures, are promising natural carriers for improving anthocyanin stability and maintaining overall colour quality in dairy and confectionery products.
This study investigates a sustainable dyeing and finishing strategy for recycled nylon 6,6 and organic cotton fabrics dyed with weld. Following meta-mordant dyeing using alum under Natural Organic Dye Standard (NODS)-compliant conditions, the fabrics were subjected to functional finishing with titanium dioxide as a multifunctional photocatalytic surface agent and sodium alginate as a film-forming biopolymeric binder. The finishing process was optimised using pad-batch and exhaust procedures, with parameters varying with the TiO2/C6H7NaO6 concentration ratio. Fourier transform infrared (FTIR) spectroscopy was employed to investigate the structural properties of the dyed fabrics and determine the molecular-level interactions between titanium, sodium alginate and the fibre matrix. Surface elemental distribution was analysed using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX). Natural dye components were identified by high-performance liquid chromatography with diode-array detection (HPLC-DAD) under fully reported, reproducible chromatographic conditions. The results indicate that the alginate-based coating improves dye fixation and fastness by forming a continuous surface film, while TiO2 enhances UV protection primarily through scattering and absorption mechanisms, thereby significantly decreasing the transmission level of UV-A and UV-B radiation.
Silk is distinguished by lightweight texture and limited water retention, leading to a light colour and fuzzy pattern during inkjet printing. Due to its proteinaceous nature, silk is susceptible to bacterial growth, which significantly impacts its functionality and poses health risks. To mitigate these issues, the silk fabric was initially subjected to plasma irradiation, followed by sequential immersion in tannic acid (TA) and chitosan (CS) solutions. This process formed a TA/CS biomass film on the fabric surface, imparting antibacterial property and resistance to ink infiltration. Subsequently, the modified silk underwent inkjet printing with gardenia blue ink, fixation through steaming, and thorough rinsing. Analyses using scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction confirmed the successful application of TA and CS without altering the primary structure of silk fibres. Under the specified modification conditions (plasma treatment 180 s, TA concentration 10 g/L, and CS dosage 2%), the printed silk exhibited a deep blue colour with a colour strength of 6.3 and demonstrated colourfastness to rubbing and washing at a grade of 4 or higher. The printed pattern was precise, with a variation in line width of less than 10% in both warp and weft directions. Moreover, the printed fabric showed a 95% antibacterial efficacy against E. coli and S. aureus, and achieved a free radical scavenging rate of 71% even after 10 soapings. Overall, this study presents a straightforward, effective, and sustainable modification approach to enhance the inkjet printing quality and antibacterial property of silk fabrics.
This study investigates the electrochemical decolorization of waste acid dye baths and evaluates their potential reuse in subsequent textile dyeing processes. Four different anode materials (iron, aluminum, stainless steel and graphite) were examined to optimize color removal efficiency and assess the influence of electrochemically generated by-products on dyeing performance. Under optimized operating conditions, aluminum anodes achieved over 90% color removal without generating harmful chlorinated species. However, fabrics dyed in these treated baths exhibited noticeable color differences (Delta E >1), attributed to aluminum's mordanting effect, which enhanced dye uptake particularly for blue dyes. Conversely, iron anodes led to residual metal contamination, while steel and graphite promoted hypochlorite formation, causing dye degradation in subsequent acid dyeing cycles. To mitigate these limitations, iron-treated baths were alkalized with Na2CO3 and successfully reused in reactive dyeing. Additionally, a membrane-separated electrochemical system effectively eliminated iron and hypochlorite, enabling the reuse of treated baths in vat dyeing applications. These findings highlight that electrochemical treatment not only facilitates substantial color removal but also supports sustainable water and chemical resource management in textile manufacturing.
