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Natural dyes are mostly used for dyeing of natural fibre textiles to improve their eco-friendly features. For successful commercial use of natural dyes, the appropriate and standardized dyeing techniques need to be adopted. Appropriate scientific techniques or procedures need to be derived from scientific studies on dyeing methods, dyeing process variables, dyeing kinetics and compatibility of selective natural dyes with minimal use of hazardous chemicals.

In the present study, different enzymes (protease, amylase, xylanase, pectinase, phytase) were used efficiently with Rubia dye by using simultaneous and two-step processes; both the processes were developed with an aim for conservation of time and energy, for the ease of industrial use. The highlights of the study are twofold: eco-friendly natural dyeing by using enzyme replacing metal mordant and room temperature dyeing, which is a completely new concept.

Experiments showed that enzymatic treatment can give good colour strength to silk fabric using Rubia as a dye source and has good potential for commercial dyeing. It is a non-toxic dye. Use of enzymes were a deliberate attempt to avoid metal mordanting in silk dyeing, as it would make textile dyeing eco-friendlier. The order of reactivity of enzymes in one-step process was found to be protease > phytase > xylanase > amylase > pectinase. Similarly, for two-step dyeing process, the order of reactivity of enzymes observed was protease > amylase > xylanase = pectinase > phytase. Protease enzyme was the best option in both the cases. Overall, it can be concluded that in the case of enzymatic treatment, the two-step process was better in terms of larger K/S values, colour coordinate values and dye adherence.

A new domain of room temperature dyeing technique has been introduced.

In the present study, different enzymes (protease, amylase, xylanase, pectinase, phytase) were used efficiently with Rubia dye by using simultaneous and two-step processes; both the processes were developed with an aim for conservation of time and energy, for the ease of industrial use. The highlights of the research are twofold: eco-friendly natural dyeing by using enzyme replacing metal mordant and room temperature dyeing, which is a completely new concept. Overall, the ease of use for industrial application. Rubia dye from Sri Lanka has been used in conjunction with different enzymes to show that metal mordanting can be easily replaced by the use of eco-friendly and biodegradable enzymes. The most attractive feature of this study is the low-temperature dyeing at 30-40°C. For any dyeing house, this process can be easily adapted on jigger, winch or even in continuous padding machine. Good fastness properties and dye adherence have been the other highlights of this study.

This paper aims to investigate the feasibility of developing an eco-friendly dyeing process for a regenerated polyester fiber (polytrimethylene terephthalate) using a natural dye (Lac) and bio-mordant.

The effects of temperature, time, initial pH of dye bath, material to liquor ratio and mordant concentration on color strength of polytrimethylene terephthalate fiber dyed with Lac were examined. The results were compared using three bio-mordant (catechu, myrobalan and pomegranate) and three inorganic mordant (alum, ferrous sulfate and stannous chloride). Single replicate of 25-design methodology was used to identify three significant factors affecting color strength, and optimization was done using response surface methodology based on 2³-central composite rotatable design.

Color strength achieved using catechu as a bio-mordant was close to that with ferrous sulfate and higher than with stannous chloride. Temperature, initial pH and mordant concentration were identified as significant factors affecting color strength of dyed fiber with catechu. Optimization revealed temperature of 133OC, initial pH of 6 and bio-mordant (Catechu) concentration of 10 per cent to be the optimal conditions for dyeing, with K/S value of 4.55.

The study revealed the possibility of satisfactory dyeing of regenerated polyester fibers with natural dyes, replacing disperse dyes. The comparison of color strength achieved indicated the possibility of replacing inorganic mordant with bio-mordant in such dyeing process. The dyeing process could thus be made more eco-friendly by removal of toxic chemicals from effluents.

This study aims to dye silk with natural pigments extract of Coreopsis tinctoria, by treating the fabrics with appropriate mordant under suitable dyeing conditions, to achieve good dyeing depth, fastness and ultraviolet (UV) protection.

Firstly, single factor experiments were used to determine the basic dyeing conditions of Coreopsis tinctoria. The optimal process conditions for direct dyeing were determined through orthogonal experiments. After that, the dyeing with mordant was used. Based on the previously determined optimal process conditions, silk fabrics were dyed with different mordanting methods, with different mordants and mordant dosages. The dyeing results were compared, in terms of the K/S values of the dyed fabrics, to determine the most appropriate dyeing conditions with mordant.

The extract of Coreopsis tinctoria can dye silk fabrics satisfactorily. Good dyeing depth and fastness can be obtained by using suitable dyeing methods and dyeing conditions, especially when using the natural mordant pomegranate rind and the rare earth mordant neodymium oxide. The silk fabrics dyed with Coreopsis tinctoria have good UV resistance, which allows a desirable finishing effect to be achieved while dyeing, using a safe and environmentally friendly method.

The composition of Coreopsis tinctoria is complex, and the specific composition of colouring the silk fibre has not been determined. There are many factors that affect the dyeing experiment, which have an impact on the experimental results.

The results of this study may help expand the application of Coreopsis tinctoria beyond medicine.

To the best of the authors’ knowledge, this paper is the first report on dyeing silk with the extract of Coreopsis tinctoria achieving good dyeing results. Its depth of staining and staining fastness were satisfactory. Optimum dyeing method and dyeing conditions have been identified. The fabric dyed with Coreopsis tinctoria has good UV protection effect, which is conducive to improving the application value of the dyeing fabric. The findings help offer a new direction for the application of medicinal plants in the eco-friendly dyeing of silk.

This study aims to observe the coloring efficacy of coffee-based natural brown colorant for cotton dyeing under microwave (MW) treatment.

The colorant extracted in particular (neutral and acidic) media was stimulated by MW treatment up to 6 min. Dyeing variables were optimized and 2–10 g/100 mL of sustainable anchors (mordants) have been used to get colorfast shades.

It has been found that un-irradiated acidic extract (RE) containing 5% of table salt at 80 °C for 50 min has given high color yield onto MW-irradiated cotton fabric (RC = 2 min). The utilization of 2% of Fe, 10% of tannic acid and 10% of sodium potassium tartrate before bio-coloration, whereas 4% of Fe, 10% of tannic acid and 6% of sodium potassium tartrate after bio-coloration has given good color characteristics. In comparison the application of 6% of pomegranate and turmeric extracts before bio-coloration and 6% of pomegranate and 10% of turmeric extracts after bio-coloration have given good color characteristics. New bio-mordants can be added to get more new colorfast shades.

There is no research limitation for this work. New bio-mordants can be added to get more new colorfast shades.

This work has practical application for artisans, textile industry and handicrafts. It is concluded that colorant from coffee beans can be possible alternative of synthetic brown dyes and inclusion of MW rays for extraction and plant molecules as shade developers can make process more green.

Socially, it has good impact on eco-system and global community because the effluent load is not carcinogenic in nature.

The work is original and contains value-added product for textiles and other allied fields.

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.

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.

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.

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.

The purpose of this study is simultaneous dyeing and mordanting of wool yarns with extracted cochineal dye and aluminum sulfate to the reduction of consuming energy, water and time.

The dyeing process was optimized using the response surface methodology (RSM) approach. pH, dyeing duration and the presence of additives were chosen as variables and the color strength of samples as a response. The color characteristics and fastness attributes of samples dyed in the best condition were evaluated and compared to pre-mordant dyeing outcomes on wool yarns.

The best conditions for deep dyeing wool with cochineal dye were as follows: pH 2.5, time 110 min and the ratio of aluminum: additives 1:0 at 100 °C. Color strength of dyed wool yarns by one-bath and pre-mordant dyeing methods were approximately the same. Wool yarns can dye to the on-bath dyeing method such that the dyed samples have similar color strength and fastness properties to pre-mordant dyeing.

Wool dyeing processes that use one-bath dyeing consume less water and produce fewer effluents. As a result, this strategy conserves water and energy for a higher quality of life. The findings of this study, in general, aid environmental protection.

A novel one-bath process for dyeing wool with cochineal dye at heavy depths is introduced. RSM was used to optimize the procedure and determine effective parameters on the color strength of dyed wools. Using extracted cochineal dye and aluminum sulfate in a simultaneous dyeing technique, good color fastness qualities on wool fibers were achieved.

Ultrasonic assisted extraction of Osage orange with a water-acetone co-solvent has been chosen in part one of this research as a model to study the shade reproducibility of dyeing silk and wool protein-based materials. The use of ultrasound to assist the dyeing parameters is studied to determine the standardization of the dyeing process. Pre and post mordanting methods by using eco-friendly mordants, alum mixed with cream of tartar, are chosen to enhance the fastness properties. Ultrasonic assistance on the mixture of alum and cream of tartar as a pre-mordant, followed by dyeing for a shorter time at a lower temperature, shows good shade reproducibility and satisfying levelness with significant fastness properties, whereas the amounts of fading are evaluated in terms of the color difference to deduce the influence of dye- fiber bonding after treatment and mordanting methods. As a result, this study offers an efficient methodology for a renewable natural yellow, a revolutionizing start towards environmental protection, and eco-friendly dyeing of protein fabrics as a potential viable option.

The purpose of this study is to investigate the physical, ultraviolet (UV), colour appearance and colour fastness properties of selected fabrics dyed with natural dyes from Daboya and Ntonso communities of Ghana. The study further highlights the rich cultural heritage of traditional dyeing from these two communities. Craftsmen in West Africa especially Ghana, have sustained the traditional dyeing methods to produce textile products for consumers.

In this study, two sample fabrics were purchased from craftsmen at Ntonso and Daboya communities in Ghana. These fabrics were analysed at the laboratory under standard test methods for their physical, UV, colour appearance and colour fastness properties.

Results showed that all the sample fabrics have good UV shielding performance (ratings above 50+). Daboya sample fabrics (dyed with indigo dyes) produced more colour stains than the sample fabrics from Ntonso (dyed with black “kuntunkuni” dyes). The K/S_sum value or colour yield reduced after washing but that alternatively increased the calculated ultraviolet protection factor.

Findings from this study exposed the unique UV performance of dyed traditional fabrics (using natural dyes) from Ntonso and Daboya communities in Ghana. This inspires and enforces the need for craftsmen to improve their production cycle to produce these fabrics in different sizes which provides the necessary UV shielding abilities for consumers in the wake of climate changes.

This study demonstrated that the natural dyeing process at the two communities produced relatively good UV and colour fastness properties of the sample fabrics. These eco-friendly dyeing practices have survived over time to maintain and promote the concept of sustainability within the textile and fashion industry in Ghana.

This paper aims to investigate the dyeability of tussah silk fabric with lotus seedpod extract as the source of nontoxic and eco-friendly dyestuffs and functional agent.

Mordant free dyeing method was carried out using citric acid (CA) as the cross-linking agent to link the fibre and dye molecules. First, the natural pigment of oligomeric procyanidins was extracted from the lotus seedpod and then used to dye the tussah silk fabric. After the dyeing process, the dyed samples were treated with CA solution under different concentrations to improve the colour fastness.

The tussah silk fabric was successfully coloured in reddish brown through the dyeing process and charactered by using Fourier-transform infrared spectroscopy spectrometer. Moreover, lotus seedpod extract could impart excellent UV protection ability to the dyed samples, and UPF values reached up to 2000. CA dosage influenced the colour characteristics, UV protection and anti-wrinkling performance. The optimum dosage of CA was 7% (Wt.%). In addition, dyed silk fabric showed good antibacterial activity and the calculated bacteriostatic rate against Escherichia coli and Staphylococcus aureus were 83.27 and 60.2%, respectively.

This bio-dyeing strategy provided a simple and effective method for sustainable tussah silk fabric dyeing process.

This paper provides a novel dyeing strategy for mordant free dyeing and functionalization of tussah silk fabric, with lotus seedpod extract as natural pigment and CA as cross-linking agent to link the fibre and dye molecules.

In recent years, natural dyes have attracted significant attention globally because of growing public awareness of the environment and health hazards associated with synthetic dyes. Natural dyes can provide special aesthetic qualities as well as the ethical significance of a product which is environmentally friendly. By keeping this burning issue in mind, this study aims to explore the dyeing properties of various unexplored environmentally friendly natural dyes.

In this study, the aqueous extract of coconut leaves is used for dyeing purpose. The silk and jute fabrics were dyed with the extract alone as well as in combination with metal salts as mordants by employing pre-, meta- and postmordanting techniques. The dyeing properties of the colored samples were evaluated by measuring their color strength; CIEL*a*b* values; and color fastness to washing, light and rubbing.

A yellow shade was achieved when the fabric samples were dyed solely with the extract. However, shade variations were observed when different mordants and mordanting techniques were applied. In all the cases, metallic salts improved the color fastness properties of dyed samples to washing, light and rubbing especially for the silk fabric.

To the best of the authors’ knowledge, this is the first report on a natural dye extracted from the leaves of coconut. Leaf as the source of dye has added an extra advantage, as it is reproducible and can be collected easily without harming the plants. The reported dye could be an attractive choice for sustainable and eco-friendly dyeing.