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Everyone is extremely concerned about environmental protection and health safety due to the rise in living standards. Plant-derived natural dyes have garnered much industrial attention in food, pharmaceutical, textile, cosmetics, etc. owing to their health and environmental benefits. The present study aims to focus on the elimination of the use of synthetic dyes and provides brief information about natural dyes, their sources, extraction procedures with characterization and various advantages and disadvantages.

In producing natural colors, extraction and purification are essential steps. Various conventional methods used till date have a low yield, as these consume a lot of solvent volume, time, labor and energy or may destroy the coloring behavior of the actual molecules. The establishment of proper characterization and certification protocols for natural dyes would improve the yielding of natural dyes and benefit both producers and users.

However, scientists have found modern extraction methods to obtain maximum color yield. They are also modifying the fabric surface to appraise its uptake behavior of color. Various extraction techniques such as solvent, aqueous, enzymatic and fermentation and extraction with microwave or ultrasonic energy, supercritical fluid extraction and alkaline or acid extraction are currently available for these natural dyes and are summarized in the present review article.

If natural dye availability can be increased by the different extraction measures and the cost of purified dyes can be brought down with a proper certification mechanism, there is a wide scope for the adoption of these dyes by small-scale dyeing units.

This study aims to improve the natural dyeing recipe with better light fastness using ascorbic acid (vitamin C) with pulverised plant dyes.

Silk fabrics pre-mordanted with alum (aluminium ammonium sulphate) were dyed using six types of plant dyes available in Sarawak, Malaysia, namely, Engkerabai leaves (Psychotria viridiflora), Ketapang leaves (Terminalia catappa), mangrove bark (Ceriops tagal), Sepang wood (Caesalpinia sappan), mangosteen husk (Garcinia mangostana) and onion skin (Allium cepa). Then, the dyed samples were immersed in vitamin C. The dyed and vitamin C-treated silk samples were exposed to direct sunlight for 40 h to test whether vitamin C had any effect on the light fastness of the dyed samples.

It was found that the fabric samples using vitamin C for after-treatment, particularly Engkerabai, Ketapang, mangrove and mangosteen, exhibited better light fastness. The colours of the four samples changed and looked darker when compared to the non-treated fabric samples. However, it was observed that vitamin C had a reverse effect on Sepang wood and onion skin. The acidic aqueous solution of vitamin C discharged the dyed samples instead.

In conclusion, depending on the plant types, vitamin C can be used to improve the light fastness of natural dyes or as a reducing agent for natural dyes.

The purpose of this research is to identify and investigate some natural dyes with halochromic properties for potential use as food spoilage indicators to reduce waste and curve the negative effects of food borne diseases.

Exactly 10 potential dye-yielding plants were selected based on their colour (mostly purple, red, maroon and pink). Solvent extraction was used to extract the dyes and pH differential method was used to determine the concentrations of anthocyanin in the extracted dyes. Different concentrations of hydrochloric acid and sodium hydroxide (0.1 M, 1 M and 2 M) in drops and in excess as acidic and basic solution, respectively, were used to test the halochromicity of the extracted dyes. Methyl red (a synthetic dye) was used as a reference standard/control. The pH of the dyes was recorded before and after addition of both NaOH and HCl solutions.

Five out of the 10 dyes extracted (labelled as dye A–E for Ti plant (green Cordyline fruticosa), coleus (Coleus blumei), paper flower (Bougainvillea glabra), painted nettle (Palisandra coleus) and purple heart (Setcresea purpurea), respectively, were found to be halochromic (even at low doses) by changing its colour when exposed to both acidic and basic solutions. While other dyes labelled F–J for red acalypha (Acalypha wilkesiana), golden shower (Cassia fistula), golden dew drop (Duranta repens), wild sage (Lantana camara var Aculeata) and pink oleander (Apocynaceae Nerium oleander), respectively, were either completely insensitive to the solutions in drops, slightly sensitive at high doses or the colour change is insignificant. Although some dyes were found to be more sensitive than others but in most cases, the colour changes in halochromic dyes were more stable in acidic conditions than in basic making it more sensitive to the basic than the acidic solution with the exception of dye A and E (to some extent) which was sensitive to both acidic and basic solution. The anthocyanin contents of dye A–J were found to be between the range of 2.28–10.35 mg/l with dye E having the lowest and dye J with the highest anthocyanin concentration, respectively. The initial pH of all the dyes falls within the range of 4.8–7.3 with most found within the acidic range.

Halochromic dye research studies are still at the infancy stage in developing world despite the vast available and abundant potential natural halochromic dye-yielding plants. The study explored this area of research and gives an opportunity for the development of smart packaging for pH-sensitive foods using natural dyes as an alternative to conventional synthetic dyes to reduce cost and also curve the negative effect of synthetic dyes as well as food borne diseases.

The purpose of this study was to review the information on the scientific efforts and achievements in sustainable industrial textile applications of natural colourants. Then the paper suggests the ways of improving the industrial textile applications of plant-based colourants.

The literature on the chemistry, sources and extraction of plant-based natural colourants was reviewed. The reviewed information was analysed and synthesised to provide techniques for selecting sustainable extraction methods, possible sustainable textile applications of natural colourants and the challenges which hinder industrial textile applications of plant-based natural colourants. The ways of overcoming the challenges of the industrial textile applications of plant natural colourants were suggested. Lastly, the current situation of industrial application of natural dyes in textiles is presented.

Despite the scientific achievement to overcome the challenges of natural colourants for textiles, the global industrial application of natural colourants is still low. Inadequate knowledge of the dyers results into poor performance of the natural dyed textile. The natural dyed textiles are expensive due to the scarcity of raw materials for manufacturing of natural colourants. The selection of suitable extraction, application methods and type of substrate should consider the chemistry of the particular colourant. The society should be educated about the benefits of natural dyed textiles. Cultivation of colourant-bearing plants should be promoted to meet the industrial material demand.

The paper provides a synthesized collection of information about the source, chemistry, extraction, textile application and challenges of plant-based natural colourants. The reviewed information was analysed and synthesised to provide techniques for selecting sustainable extraction methods, possible sustainable textile applications of natural colourants and the challenges which hinder industrial textile applications of plant-based natural colourants. The ways of overcoming the challenges of the industrial textile applications of plant natural colourants were suggested.

Dyeing process is usually to blame negatively for deteriorating the environment. Eco-friendly silk fibers are able to exercising their commercial values well followed by eco-friendly processing. One of the supporting examples is the process of changing the colors of silk fabrics. This would include the dyeing process used to change the colors of silk fabric. The intention of the study is to reach the goal of creating an eco-friendly finishing process using a local natural plant-based indigo dyeing process that would complement an eco-friendly degumming process. Currently, most dye houses use sodium hydrosulfite (Na₂S₂O₄) and alkali (NaOH) as the substances for providing hydrogen as a reducing agent. Since the sodium hydroxide by-products are acidic, they may damage equipment in the dye houses, generate air pollution in working environment. The other problems associated with the use of sodium hydrosulfite are the cost and instability with low storage.

This paper is based on continuing improvements to the commercialization of the raw materials via the innovative degumming process elaborated in the author’s previous study: “Degumming of Silk Fibers by CO₂ Supercritical Fluid.” The initial study has already proved that it was possible to remove sericin from raw silk fiber by using an organic acid pretreatment and CO₂ supercritical fluid over the heavy processes the industry currently deploys. The sericin removed from this innovative and eco-friendly processing of silk fiber will be remained in a clean state, not in the form of waste via the existing technologies in use. Clean sericin, rich in silk protein with high market values, can be a potentially perfect substitute of collagen the medical and cosmetic industries widely use. The continued research is focused on the other by-product coming out from this eco-friendly degumming process the silk fibers post degumming. Dyeing process is usually to blame negatively for deteriorating the environment. Eco-friendly silk fibers are able to exercising their commercial values well followed by eco-friendly processing. One of the supporting examples is the process of changing the colors of silk fabrics. This would include the dyeing process used to change the colors of silk fabric. The intention of the study is to reach the goal of creating an eco-friendly finishing process using a local natural plant-based indigo dyeing process that would complement an eco-friendly degumming process.

Degumming is an important stage in the silk manufacturing. Due to removing sericin from silk fibers, when subjected the degumming process, these silk fibers acquire the properties, which are of high consumer and commercial values, those include gloss, perfect color, soft handle and texture, elegant drape. Another purpose for the silk fabric degumming is preparing for the next step in processing, such as dyeing or printing. The author has developed a new approach to the degumming process exploiting a supercritical fluid carbon dioxide and found it as a good alternative to the conventional methods that are currently used in industry. Silk fabrics treated by the scCO₂ degumming process are characterized by improved dyeing ability or color strength, while this process does not adversely affect the environment. The implications or potential applications of the findings: as it is clearly seen from Table 1, the effectiveness of the degumming process can be improved by at least 38% applying scCO₂. Moreover, implementation of the scCO₂ silk degumming process into the textile industry may help manufactures to consume less water and energy resources (Elmaaty and Abd El-Aziz, 2017), as well as to obtain pure sericin as a valuable end-product that can be used in the medical and cosmetic industries.

The innovation and novel aspects of research: degumming is an important stage in the silk manufacturing. Due to removing sericin from silk fibers, when subjected the degumming process, these silk fibers acquire the properties, which are of high consumer and commercial values, those include gloss, perfect color, soft handle and texture, elegant drape. Another purpose for the silk fabric degumming is preparing for the next step in processing, such as dyeing or printing. The author has developed a new approach to the degumming process exploiting a supercritical fluid carbon dioxide and found it as a good alternative to the conventional methods that are currently used in industry. Silk fabrics treated by the scCO₂ degumming process are characterized by improved dyeing ability or color strength, while this process does not adversely affect the environment.

The author has developed a new approach to the degumming process exploiting a supercritical fluid carbon dioxide and found it as a good alternative to the conventional methods that are currently used in industry. Silk fabrics treated by the scCO₂ degumming process are characterized by improved dyeing ability or color strength, while this process does not adversely affect the environment.

As it is clearly seen from Table 1, the effectiveness of the degumming process can be improved by at least 38% applying scCO₂. Moreover, implementation of the scCO₂ silk degumming process into the textile industry may help manufacturers to consume less water and energy resources (Elmaaty and Abd El-Aziz, 2017), as well as to obtain pure sericin as a valuable end-product that can be used in the medical and cosmetic industries.

To make the silk manufacturing more green, the author has developed a technology for obtaining a plant-based indigo dye applying only locally grown agricultural products. The author has found that banana paste and banana peel paste have a sufficiently enough reduction potential for converting the indigo dye into indigo white, which is an important stage in the dyeing processes. The investigation performed showed that both these pastes can serve as a green alternative to sodium hydrosulfite, widely used in industry as a reducing agent. The main result of this study is the demonstration that natural, recyclable and easily biodegradable resources can be exploited to produce the semi-products for the textile industry and the final dyed silk fabrics as well. Summarizing the above, it can be concluded that we have got the results, which show promising alternative green processes for the textile industry in silk treatment (both degumming and dyeing). Their implementation may turn the silk textile production into a sustainable green circle and economically viable manufacturer.

The majority of the synthetic dyes have been found to be non-biodegradable, toxic and carcinogenic. As a result, there has been a growing trend toward the use of natural dyes as alternates to synthetic dyes. This shift calls for more research to come up with more sources of natural dyes to satisfy their increasing demand. Euclea divinorum plant has been used traditionally as a source of dye, however, its textile dyeing properties have not been studied. This study aims to determine the textile dyeing properties of E. divinorum extract.

Optimization of dyeing conditions of Euclea divinorum natural dye extract on the cotton fabric was done using response surface methodology (RSM). The combined effects of examined dyeing conditions on the relative color strength (K/S) were studied using a central composite experimental design. Analysis of variance (ANOVA) was used to determine the significance of the statistical model generated for the study. Mordanting effects were measured using standard ISO wash, rub and lightfastness tests.

The optimum dyeing conditions were found to be 68 min, pH 3.3 and 82°C with color strength 0.609. Temperature and pH showed some interaction effects during the dyeing experiments. The predicted optimum K/S value was validated experimentally using the optimum conditions and was found to be in agreement with the experimental values. All the metallic mordants used enhanced the color strength and provided a variety of brown shades, therefore, a suitable alternative for the toxic synthetic dyes.

Optimization of dyeing conditions of Euclea divinorum dye on cotton using RSM and mordanting at optimal conditions has not been done elsewhere.

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.

PPlants have been grown for natural dyes to produce a wide range of colors.. N Natural dyes become increasingly important these days as synthetic dyes cause serious damage to the environment and have to be replaced. The published records show that Turkey has about 10,000 taxa of higher plants, 145 of which come from 92 genera and 51 families and can be used as dyeing sources of 17 colors. The most common families used for dyeing are Asteraceae, Rosaceae, Lamiaceae, Polygonaceae and Euphorbiaceae, and the dominating genera are Rumex, Anthemis, Euphorbia, and Salvia. Dye plants are of great medicinal value as well and can be used for producing antihelmintic, antiseptic, appetizer, carminative, diuretic, exudative, laxative, sedative and stomachic preparations.

The paper aims to investigate the feasibility of developing natural dyes from the barks of Araucaria columnaris and leaves of Macaranga peltata, Averrhoa bilimbi. The paper also deals with the application of natural dyes in textile coloration.

Dye extraction was carried out using the aqueous method. The dyeability of the aqueous extract was assessed on cotton, silk and polyester yarns using different mordants (alum, acetic acid, CuSO₄, lemon juice) and without mordant. UV–Visible spectral analysis and pH of different natural dyes were determined. Percent absorption, K/S values, CIELab values and fastness properties of the selected dyed yarns were also assessed.

The percentage values for dye exhaustion differed with various mordants. The K/S values were found to be influenced by the addition of mordants. Different hues were obtained with the usage of different mordants. Fastness results exhibited good to very good grades.

The effective application of aqueous method of dye extraction in the study avoids solvent toxicity. The current results proved that the dyeing could be achieved at room temperature for different yarns (cotton, silk, polyester). At present, no report exists in the literature of research work on the extraction of natural dyes from the leaves of M. peltata, A. bilimbi and their dyeing potential on cotton, silk and polyester.

The present work offers new environment-friendly dye as well as simple dyeing method. Barks and leaves are promising sources of dye. Enormous availability of barks and leaves avoids the exploitation of the plant parts for the extraction of natural dyes.

The important feature of this study was the effective dyeing of natural and synthetic fibers at room temperature. The novel sources of natural dyes would contribute significantly to the existing knowledge of dyeing, and the natural dyes reduce the environmental impact of synthetic dyes.

Examines the tenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects. Subjects discussed include cotton fabric processing, asbestos substitutes, textile adjuncts to cardiovascular surgery, wet textile processes, hand evaluation, nanotechnology, thermoplastic composites, robotic ironing, protective clothing (agricultural and industrial), ecological aspects of fibre properties – to name but a few! There would appear to be no limit to the future potential for textile applications.