Color Strength Research Articles

SUSTAINABLE DYEING OF MODIFIED COTTON FABRIC WITH REMAZOL DYES IN THE ABSENCE OF SALT AND ALKALI

This research work investigates the chemical modification of cotton cellulose with a cationizing agent (CHPTAC, 3-chloro-2-hydroxylpropyl trimethyl ammonium chloride), which resulted in the enhanced dye uptake and increased color strength (K/S) on the dyed cotton fabric in the absence costly auxiliaries, such as sodium chloride and sodium hydroxide. The modified and unmodified cotton fabric samples were dyed using the exhaust dyeing method on a high-temperature dyeing machine with several reactive dyes of the Remazol class in different shade depths. The dyed samples were washed, dried and tested for K/S and colorfastness properties (washing, rubbing, and light), using standard test protocols. The results revealed that the color strength and the colorfastness properties of the modified dyed cotton fabric were significantly better than those of unmodified cotton. Thus, this study attempted a sustainable approach in cotton dyeing without using salt and alkali.

COLOR STRENGTH AND COLOR DIFFERENCE OF COTTON AND SILK FABRICS DYED WITH EXTRACTS FROM BUTTERFLY PEA FLOWERS

Natural dyes have always been of interest due to their non-toxicity and environmental benefits. In this work, cotton and silk fabrics were dyed with extracts from butterfly pea (BP) flowers. Accordingly, the effects of pH value, liquor ratio, dyeing concentration, temperature, exhausting time and mordanting agents on the color strength (K/S) and the color difference (E) of cotton and silk fabrics dyed with BP extracts were investigated. The experimental results showed that the K/S and E values of dyed cotton fabrics were much higher than those of dyed silk fabrics. The research also established the most suitable conditions for dyeing cotton and silk fabrics with BP extracts as being the following: pH of 6.0, liquor ratio of 1:5, dyeing time of 60 min, at 70 °C for cotton and 60 °C for silk. Notably, four different types of mordants, including potassium aluminium sulfate (KAl(SO4)2.12.H2O), copper sulfate (CuSO4.5H2O), ferrous sulfate (FeSO4.7H2O) and tannin, were used to enhance dyeability of cotton and silk fabrics with BP extracts. There were slight differences in the E values of mordanted and unmordanted samples, while the K/S values improved significantly, especially in the samples mordanted with tannins. Color fastness and color staining to washing and rubbing were also examined, indicating that treated silk fabrics achieved higher values than treated cotton fabrics.

Environmentally Friendly Coloration of Polyamide Fabrics with the Use of Natural Dyes: A Study Including Results of Industrial Scale Applications

In recent years, it is seen that there have been many publications on natural dyes in literature. In the studies carried out, one or more plants were taken and the color and fastness obtained with them in the presence of different mordants were examined. Beyond that, functionalities such as odor, antibacterial activity, and UV protection that natural dyes impart to the fabric were examined. However, the important thing that the literature needs is to represent also the results related to the industrial scale production since industry shows high interest to be able to use natural dyes. In this study, seven plant dyes have been used for the coloration of polyamide fabric. The studies have been conducted both on an industrial scale and at the laboratory scale. Based on the statistical analyses, four dyes with the highest color strength and fastness properties including catechu, madder, mulberry leaf, and pomegranate peel were selected for more studies on industrial scale. The results confirmed the good color strength and satisfactory fastness properties against repeated washing, rubbing, water, and perspiration for all selected dyes. The samples dyed with those dyes exhibited excellent protection against UV radiation. The results obtained in this study showed the potential of the selected natural dyes in eco-friendly industrial dyeing of nylon fabric with acceptable fastness properties.

Standardization and optimization of concentration of different mordants on the dyeing efficiency of Lawsonia inermis (Henna) on silk fibre

The natural dye henna usually being recognized as lawsone is a red-orange pigment that has long been used for the coloration of skin and hair as well as textile materials. This natural colorant garners the attention of researchers throughout the globe for the coloration of textile materials due to the fact that its color can easily be harmonized with nature. In the current study, concentration of different mordants (ferrous sulphate, alum, copper sulphate, and citric acid) were standardized on silk fibre using henna dye. To obtain the results, the study was divided into two experiments. The dyed fibre samples were analyzed for absorbance, color coordinates color strength, and color fastness properties. In experiment-I, standardization of different mordants at different concentrations were done while dye percentage was kept constant at 15%. Based on colour and acceptability results, ferrous sulphate at 2 and 4% was selected. In experiment II, optimization of the level of ferrous sulphate at 2, 3, and 4% was used along with 15% henna dye. Based on the results, it was concluded that 15% of henna dye along with 3% of ferrous sulphate gave better results on silk fibre.

Comparative Study on Dyeing Behaviours of Tasar and Tasar Blended Silk Fabrics

Tasar silk is widely sought after because to its natural beauty, durability, sustainability, and cultural relevance. Despite the long-standing yearning for Tasar textiles in their natural colour, weavers can only manufacture a limited number of different designs and types of the silk.It has become necessary to dye the Tasar fabric a different colour since the younger generation requires 100% Tasar cloths in a range of styles and colour combinations.Some manufacturers are now dyeing Tasar fabrics in smaller quantities, but their processing quality is subpar due to non-compliance with correct procedures for color concentration, time intervals, and warm washing, resulting in uneven dyeing, inconsistent hues, and poor fastness attributes.However, considering the current circumstances, it is essential that the Tasar Silk Industry understands how both pure Tasar fabrics and Tasar-blended fabrics are endowed with the fastness properties of Lanaset, Acid, and Reactive dyes.In this article, a comperative study was carried out to understand the dyeing behaviour of Acid, Lanaset and Reactive dye on Tasar x Tasar fabrics and Tasar x Mulberry fabrics. The fabric samples were prepared accordingly to evaluate the tensile properties, colour fastness to rubbing, perspiration, washing & light and colour strength. According to the findings, reactive dyeing had a larger percentage of strength loss than Lanaset and acid dyeing. Relative to other materials, acid-dyed fabrics required less washing, according to fastness data. However, reactive dyed fabrics did not perform well when it came to perspiration fastness. Lanaset dyed fabrics reacted faster to light than other types due to the presence of metal ions. The studies also showed that materials colored reactively had stronger color retention. This attempt shall provide the blue print for the industry to emulate in the future.

A study of the effect of organic acids (gallic acid and ascorbic acid) on the coloration and functionalization of wool yarns with Millettia laurentii sawdust natural dye

Wastewater from the textile industry, especially the dyeing sector, is a major contaminant for aquatic ecosystems. Synthetic dye compounds and metal salts from leftover mordant and dyeing baths are washed into rivers, endangering aquatic life and the environment. In regards to the current study’s examination of Millettia laurentii sawdust’s potential as a natural color source, eco-friendly organic acids (gallic acid and ascorbic acid) were studied in conjunction with small amounts of metal salts (aluminum sulfate, stannous chloride, copper sulfate, and ferrous sulfate) for enhancing the color shade palette with simultaneous functionalization (antimicrobial and UV-protection) of wool yarns. The effects of metal salts up to ecologically permissible concentration limits on the dyeing and functional properties were assessed in combination with organic acids. The study focused on optimizing dyeing variables including pH (2–8), temperature (65–95 °C), dye concentration (25–125% o.w.f.), and dyeing time (15–90 min) using a one-factor-at-a-time (OFT) optimization by determining the color depth (K/S) values on the wool yarns. The optimized dyeing conditions were pH of 4, temperature of 95 °C, dye concentration of 75.0% (o.w.f.), and dyeing time of 60 min. The color characteristics (CIEL*a*b*c*ho) and fastness (Wash, rub, and light) properties are evaluated comparatively against control dyed wool yarns using standard methods. The antimicrobial activity of control dyed and mordanted dyed wool yarns was evaluated in terms of the percentage microbial reduction of bacterial colonies. Metal salts especially ferrous sulfate in conjunction with gallic acid (Fe/GA) provided the highest average color strength (13.50) with a maximum percentage microbial reduction of 96.67%. UV protection ability was assessed by an Australian and New Zealand standards (AS/NZS 4399: 1996) method in terms of UPF values. UV protection levels were significantly improved by using binary combinations of organic acids and metal salts with the maximum protection offered by Fe/GA (97.66) and Sn/GA (97.90). Dyeing outcomes were significantly impacted by the chemical structure of organic acids (gallic acid and ascorbic acid) and the type of metal salts; the research proposes a more environmentally friendly natural dyeing process for the textile industry.

Viscose fibers decorated with silver nanoparticles via an in-situ green route: UV protection, antioxidant activities, antimicrobial properties, and sensing response

Multifunctional cellulosic fibers are in high demand for use in a variety of applications. Functional cellulosic fibers obtained through green and sustainable approaches are getting special attention because of the need to limit the environmental impact of hazardous chemicals. Herein, a novel facile, efficient, and eco-friendly approach for multifunctional viscose fibers@Ag NPs (VF-Ag) was designed by a rapid, facile, and one-pot biosynthesis green route using guava leaf extract as a reducing and stabilizing agent. UV–Vis, TEM, SEM, EDX, FTIR, and XPS were used to analyze the formation of silver nanoparticles and their subsequent deposition on the surface of viscose fibers. The silver nanoparticles immobilized on the surface of viscose fibers endowed a yellow/brownish color to the fibers as well as improving the dyeing with reactive dye. The VF-Ag samples have multifunctional properties like protective activities against UV radiation and microorganisms, antioxidant activity, and sensor ability toward Hg2+. The results demonstrated that the UPF values of VF-Ag samples ranged from 280 to 355 compared to 103 for VF. The antioxidant activities of VF-Ag ranged from 79 to 85% compared to 9% for VF. VF-Ag samples exhibited excellent antimicrobial activities against Gram-positive and Gram-negative bacteria, very good activities against yeast, and low activities against fungus.VF and VF-Ag were dyed using reactive dye (CI-reactive blue-19) at two color intensities (2.5, and 5%). The results show that the color of VF turned blue, while the color of VF-Ag turned greenish. The color strength of VF-Ag significantly increased with increasing silver content. Furthermore, VF-Ag showed high sensitivity to naked-eye colorimetric sensing for the detection of Hg2+. In straightforward, this innovative approach provides an easy, quick, and low-cost that will open the door for a range of versatile applications for modified viscose fibers in the fields of medical and analytical applications.

Assessing the dyeing efficacy and environmental impact of cotton fabric dyed with sawmill bio‐waste extracts and metal salts

AbstractTextile coloration is a complex process involving the interaction of dye molecules with fibers in a dye bath. Synthetic dyes pose environmental hazards, leading to increased interest in natural dyes sourced from plants, animals, and minerals. However, natural dyes often require mordants for application to textiles. Despite their eco‐friendliness, natural dyes can exhibit poor wash fastness on fabrics, necessitating further research to enhance their performance. This study investigates the use of mahogany sawdust extract as a natural dye for cotton coloration, focusing on the enhancement of fastness properties through metallic mordants and associated environmental risks. Mahogany sawdust, rich in flavonoids and tannins, shows promise as a sustainable alternative to synthetic dyes. The dyeing process involves the extraction of natural dyes from sawmill bio‐waste and subsequent application onto cotton fabrics using various metallic mordants. Evaluation of colorfastness properties, color strength, color coordinates, tensile strength, FTIR, and SEM analysis provides insights into the dye‐fiber interactions and fabric properties. Environmental risk assessment considers metal exhaustion onto fabric surfaces, residual metal concentrations in mordant baths, and metal content in dyeing wastewater. Overall, this study contributes to the development of sustainable dyeing processes and highlights the importance of environmental considerations in textile coloration.Highlights Mahogany sawdust extract: potential natural dye for sustainable cotton coloration. Metallic mordants enhance colorfastness and fabric durability in dyeing processes. Comprehensive analysis reveals the intricate dynamics of dye‐fiber interactions. Environmental risk evaluation guides sustainable textile manufacturing practices. Research paves the way for greener, more sustainable textile industry practices globally.

Synthesis and polyester printing applications of transition metal complexes of tridentate 5-(m-tolyldiazenyl)salicylaldehyde thiosemicarbazone derivatives

Thiosemicarbazone metal complexes are intriguing molecules with a variety of applications in several fields, including the pharmaceutical sector, analytical chemistry, and textile industries. Here, we designed and synthesized 12 transition metal complexes based on thiosemicarbazone as a tridendate group and azo moiety as a chromophore part, in addition to evaluating their color strength and fastness properties. The tridentate ligand derivatives of 5-(m-tolyldiazenyl)salicylaldehyde thiosemicarbazone reacted with four transition metal salts (copper, cobalt, nickel, and iron salts) in refluxing alkaline ethanol to afford the corresponding thiosemicarbazone complexes. The ligands behaved as double-deprotonated tridentate ligands that connected to the transition metal ions through the deprotonation of phenolic-OH and thiol-SH, as well as the azomethine nitrogen atom, to generate fused five- and six-membered heterocycle rings. The obtained metal complexes were characterized by elemental analyses, atomic absorption, IR, and UV–Vis spectra. The color strength and fastness properties of the printed fabrics were tested, showing good to excellent properties.

An Investigation of Fastness and Potential Antibacterial Features on Cotton Fabric Colored with Novel Azo Compounds

Novel azo compounds were synthesized by diazotization of aniline and of 3-aminopyridine in the presence of NaNO2 and HCl, followed by coupling with 2-methylresorcinol in alkaline media. The structures were characterized using FT-IR, 1H NMR, and 13C NMR analysis. The main purpose of the present study is to investigate coloration applications, and antibacterial and fastness properties of the new azo structures in textile industry. Exhaust dyeing processes were applied on cotton fabric. Color strength ( K/ S values), L, a*, and b* values were measured. The color fastness values (to rubbing, light, perspiration, washing) of azo compounds on cotton fabric were presented according to ISO standards for comparison. Antibacterial activity assessment of the colored fabrics was performed according to AATCC 147-2016 test method against two types of bacteria: Staphylococcus aureus and Klebsiella pneumoniae. The fabric dyed with 2-methyl-4-[pyridin-3-yldiazenyl]benzene-1,3-diol demonstrated acceptable antibacterial activity against S. aureus.

Investigation of the Dyeing Ability of Some Reactive Triazine Azo Dyes Containing Pyrazole Fragment.

The IR, 1H NMR, and DFT studies indicated that the prepared reactive disperse dyes predominately exist as hydrazone tautomers. The electronic absorption spectra in methanol were observed and compared to those computed using B3LYP/6-311G(d,p). The dyeing efficiency of the produced dispersed reactive dyes was examined on polyester, cotton, and polyester/cotton blended fabrics. The degree of exhaustion and the quick properties of the dyed samples in terms of perspiration, washing, scorch and light fastness were assessed. It was found that reactive disperse dyes under investigation have a higher affinity for dyeing polyester textiles than cotton textiles. Moreover, the reflectance and color strength of the synthesized dyes were measured and discussed.

OPTIMIZING PIGMENT PRODUCTION FROM PENICILLIUM SP. FOR SUSTAINABLE SILK DYEING

This study explores the use of microbial pigments from Penicillium sp. as a sustainable alternative to synthetic dyes in textile dyeing, focusing on optimizing pigment production and assessing color fastness on silk. Static Potato Dextrose Broth (PDB) at 28°C produced the highest concentration of red pigment after 27 days of incubation, with an optical density (O.D) of 1.010 at λmax = 530 nm. In contrast, 15°C resulted in slower pigment production (O.D = 0.860), and 37°C showed negligible growth. Adjusting the PDB pH to 5 increased pigment yield, aligning with previous studies showing Penicillium sp. thrive in acidic conditions. The final broth pH decreased to 4.0 due to organic acid production by the fungus.Silk samples dyed with these pigments were evaluated for color strength and fastness. The colorimetric values indicated moderate color intensity (K/S = 4.25) with a bright, pastel-like appearance (L* = 81.23), and a warm reddish-yellow hue (a* = 9.23, b* = 6.48). Fastness tests showed excellent performance for dry rub (rating 5), good results for wet rub (rating 4), and favorable wash fastness (rating 4 for staining and color change). However, light fastness was lower, suggesting potential fading under prolonged exposure.Overall, the study identifies Penicillium sp. as a promising source of natural dyes for silk, with optimized fermentation conditions (PDB, 28°C, pH 5, 27 days) leading to high pigment yield and strong fastness performance, offering a sustainable alternative to synthetic dyes in textiles.

Extraction of Natural Dyes from Delonix regia Flowers for Cotton Fibres

Textile colouration is among the major industry that pollutes the environment with effluents rich in dye chemicals. Most of the dyes used are synthetics which possess health and environmental impacts. Potentially, the use of bio-based dyes and other chemicals can lessen the environmental challenges of the textile effluents. This study reports on sustainable extraction and dyeing of cotton fabric using extract of Delonix regia flowers. The extraction process was done using acid-ified water as a solvent and the dyeing process was free from hazardous auxiliary chemicals. To improve the dyeing performance, banana sap was used as an affordable and eco-friendly bio-mordant. To optimise energy consumption, dyeing experiments were done between room tem-perature and 90 °C. The dyeing performance was assessed through wash fastness, rub fastness and colour strength tests. The cotton fabric was successively dyed with the Delonix regia flowers extract rich in anthocyanin pigments in the presence of banana sap bio-mordant. The optimum dye performance was obtained at a dyeing temperature of up to 60 °C, above which the perfor-mance was negatively affected.

Investigation of the fastness properties and color strength of dry and wet reeled Tasar silk yarns

Tasar silk is extremely sought-after due to its natural beauty, toughness, sustainability, and cultural significance. Despite the historical need for Tasar textiles in their natural hue, weavers have created a limited number of unique designs and variants of Tasar silk. Since the younger generation requires 100% Tasar fabric in a range of items with diverse patterns and color combinations, it has become more vital to dye the Tasar yarn a distinct color. The fastness characteristics and color strength of Acid, Reactive, and Lanaset dye on dry reeled and wet reeled Tasar silk yarns were compared in this paper. In order to assess the yarn samples' color intensity and resistance to rubbing, sweat, washing, and light, they were treated appropriately. The findings of the fastness test showed that, in comparison to other yarns, acid and reactively colored yarns had lower washing and sweat fastness, respectively. Better light fastness was seen in fibers colored with Lanaset. Comparing reactive dyeing to acid and Lanaset dyeing, the former demonstrated a stronger color.

A comparative research on knitted fabrics washed with eco‐friendly detergent for different washing cycles

AbstractThe laundering process stands as the most commonly employed method for the maintenance of textile products. This investigation focused on boron, a pivotal mineral resource for our nation, and aims to elucidate alterations in fabric properties, specifically about colour changes and pilling, after the utilisation of various washing detergents. Comparative analyses and assessments were conducted across three distinct washing cycles, employing three distinct detergents: a boron‐infused washing detergent, a standard detergent conventionally utilised in textile trials, and a widely adopted commercial detergent. The investigation encompassed three diverse fabric constituents—cotton, polyester, and viscose—subjected to scrutiny in terms of fabric parameters subsequent to 1, 5, and 25 washing cycles. Following the laundering processes conducted at 40°C, evaluations were conducted concerning the pilling degree and colour alteration of the fabrics. Consumer perception regarding colour alterations, and subjective colour assessments was undertaken with a panel of 10 individuals. Furthermore, the research delved into the stain removal efficacy of the boron‐infused washing detergent. To assess stain removal, all fabrics were intentionally stained with six diverse contaminants: ketchup, mayonnaise, coffee, sweetened coffee, tea, and sweetened tea. A post‐washing evaluation of stain conditions was carried out subjectively by an assembled arbitration committee. Over the course of 25 washing cycles, it was observed that the boron‐containing detergent notably diminished colour strength, particularly evident in polyester and cotton fabrics. Pilling outcomes indicated a decrease in pilling as the number of washing cycles increased. Boron‐containing detergent, denoted as detergent B, consistently demonstrated commendable stain removal properties, particularly on cotton fabric.

Optimisation of cationic dye dyeing process of Porel fabrics using response surface methodology

AbstractPolyethylene terephthalate (PET) fibre, widely utilised across diverse industries, suffers from inherent drawbacks such as inadequate moisture absorption, limited hydrophilicity, and susceptibility to static electricity. To address these limitations, Porel fibre has emerged as a novel modified polyester fibre that incorporates flexible aliphatic polyester into its macromolecular chain. This innovative design not only overcomes the deficiencies of PET fibre but also enables it to be dyed using cationic dyes or disperse dyes under atmospheric pressure conditions. However, the investigation of the dyeing process of cationic dyes on Porel textiles remains relatively scarce. In this work, response surface methodology (RSM) was used to optimise the dyeing process of Porel fabrics with C.I. Basic Blue 162. The effects of dyeing temperature, dyeing time, and dye concentration on exhaustion percentage and colour strength (K/S value) were investigated using the Central Composite Design (CCD) method. The optimal dyeing process condition was as follows: a dyeing temperature of 96°C, a dyeing time of 51 min, a dye concentration of 3.6% owf, a dye solution pH value of 4–5, and a liquor ratio of 1:20. Under the optimal dyeing process conditions, the Porel fabrics achieved an exhaustion percentage of 96.2% and a K/S value of 36.0. The aforementioned efforts endow Porel fibre with high‐quality dyeing capabilities and broaden the application prospects of polyester textiles.

Sabun Homemade Dengan Ekstrak Vitis Vinifera Menggunakan Framming Time

Natural soap is one of the products that do not use chemicals that people need to clean the body and maintain healthy skin. Vitis vinifera and olive oil contain antioxidants and antimicrobials that are useful for brightening and moisturizing skin, increasing skin cell turnover, and making skin healthier. This research aims to obtain natural soap made from olive oil with the addition of grape extract (Vitis vinifera). The research method includes the process of making grape extract soap with varying framing times (3, 5, and 7 days), then the grape soap is stored for 4 weeks followed by analysis of pH levels, crack tests, and organoleptic tests including texture, color strength and foam. The final pH test results were in the range of 9.0-11.0 which were checked in the first seven days. This soap has texture ranges from 2.50 (slightly soft) to 3.84 (hard), soap color ranges from 3.15 (slightly interesting) to 4.00 (interesting), and foaming power ranges from 3.00 (slightly foamy) to 3.50 (foamy).

Clean synthesis of silver nanoparticles (AgNPs) on polyamide fabrics by Verbascum thapsus L. (mullein) extract: characterization, colorimetric, antibacterial, and colorfastness studies.

The production of antibacterial colored textiles using nanomaterials (NMs) has become an ideal goal from both a research and industrial perspective. In this study, the clean synthesis and characterization of silver nanoparticles (AgNPs) on polyamide fabrics were performed using mullein extract for the first time. Natural dyes were extracted from mullein leaves using an ultrasonic method, with an optimal amount of 15g/L. The synthesized AgNPs in different ratios of mullein extract and Ag ions were analyzed (using UV-visible spectroscopy) and dynamic light scattering (DLS). It was found that AgNPs synthesized with a ratio of 1:4 of mullein extract: to Ag ions had a diameter of 85nm. The active site groups of the synthesized AgNPs were characterized using Fourier transform infrared spectroscopy (FT-IR). Nylon fabrics dyed with different ratios of mullein extract and Ag ions exhibited acceptable color strength values (K/S) of 3.36. Furthermore, the reduction in bacterial growth for dyed fabrics improved with an increase in the ratio of Ag ions, with a 100% reduction observed for a sample dyed with mullein extract: Ag ions at a ratio of 1:4. Overall, this method offers a simple, low-cost, and compatible process with environment without the consumption of any chemicals to producing nylon with acceptable antibacterial and dyeing properties.

The effect of jack bean (Canavalia ensiformis L.) starch modification annealingheat moisture treatment on physical and chemical characteristics of biscuit

Biscuits are one of the food products that are in great demand by the people of Indonesia with a consumption growth rate of 4.25% from 2016 to 2020. Biscuits have the characteristics of low moisture content so they have a long shelf life. In this study, innovation was carried out on the main raw material of biscuits using the substitution of jack bean starch (Canavalia ensiformis L.) modified by annealing-heat moisture treatment (HMT). This study aimed to determine the effect of HMT and annealing-HMT on the physical and chemical characteristics of biscuits and to determine the best biscuit formulation. The design used in this study was completely randomized design (CRD) with one factor in the combination of modified starch and biscuit formula, namely control (100% flour), native starch (100%), native starch: wheat (50:50), native starch (100%), HMT modified starch: wheat (50:50), HMT modified starch (100%), annealing HMT modified starch: flour (50:50), and annealing HMT modified starch (100%). Based on the research, it was found that the substitution of wheat flour using annealing HMT modification starch affects brighter color, lower hardness and fracture strength, lower moisture content, ash content, fat content, and protein content, as well as increment in carbohydrate content. The best formula was determined based on multiple attributes, namely the F7 formula with 100% annealing HMT starch modification.

Investigation of process parameters for eco-friendly indigo dyeing of cotton fabric with reducing sugars

Purpose The application of indigo dyes in the denim industries has been criticised due to the introduction of non-renewable oxidation products into the environment. Previous studies have investigated that reducing sugars can be used as green alternatives to sodium dithionite in the indigo dyeing of cotton fabric owing to their reduced and stable redox potential in the dye bath. The purpose of this study was to dye denim cotton fabric with indigo dye using various reducing sugars and alkalis. The use of sucrose and potassium hydroxide (KOH) for indigo dyeing has been explored for the first time. Design/methodology/approach A mixed factorial design with four variables including alkali, pH, number of dips and type of reducing sugar at different levels was studied to identify a significant correlation between the effect of these variables on the colour strength and fastness properties of the dyeings. Findings Investigations were made to examine the significant factors and interactions of the selected responses in the eco-friendly dyeing method. This process has the potential to reduce the load of sulphite and sulphate generated in the dyebath due to the use of a conventional reducing agent, sodium dithionite. The colour strength of the dyeing reduced with fructose was found to be better than other reducing sugars and significantly influenced by the number of dips, pH levels and the interaction between pH and reducing sugars. Using fructose for indigo dyeing with two dips at a pH of 11.5, using KOH as an alkali, results in higher colour strength values. The fastness properties of the indigo-dyed sample with reducing sugars ranging from fair to good or good to excellent. Specifically, colour change receives a rating of grey scale 3–4, staining 4–5, dry rubbing 4 and light fastness 3–4. These assessments hold true across various factors such as the type of reducing sugar, alkali, pH and the number of dips. The optimised parameters leading to improved colour strength and fastness properties are also discussed. Originality/value This dyeing technique is novel and a green alternative to dithionite denim dyeing. This process is found to be useful for indigo dyeing of denim fabric leading to reduced and stable redox potential in the dyebath and acceptable colour strength of the dyed fabric.