Potential of natural dyes in silk dyeing: Trends, challenges and future prospects

Introduction

Color is one of the most powerful elements in design and communication, significantly influencing human psychology, emotions and behavior. In the textile industry, color is not just a matter of aesthetics-it serves as a vital tool to convey mood, identity, cultural values and consumer preferences. Dyeing and printing processes are the coloration techniques that adds value to the textile materials (Dessie and Eshetu, 2021) [1] . Presently, the concept of green fashion has taken the spotlight in textile and clothing industry, because of which efforts are being made to reduce the environmental impact by this industry (Sarma et al., 2025) [2] . Silk has been cherished for its luxurious texture, natural seen, cultural significance, durability. Silk shows high affinity towards dye because it rich in amino and carboxyl groups along with its hydrophilic nature (Yasukawa et al., 2021) [3] . In this contemporary era, concerns over the environmental impact, use of natural dyes have led to a renewed interest over synthetic one, especially for dyeing of silk. Though the synthetic dyes are used widely by the textile industries because of its availability, reproducibility, better color fastness etc., due to some carcinogenic chemicals required to produce these along with the effluents created on using them there is a global surge in the demand for natural dyes (Gokarneshan, 2022) [4] . Natural dye can successfully replace certain harmful synthetic dyes due to their eco-friendly nature (shah and Patel, 2012). Natural dyes can be extracted from different sources like plants, animals and from the minerals (Gokarneshan, 2022) [4] . Addressing the global bioeconomy trend, dyeing the silk with natural dye can boost the global demand of silk in the textile market.

Historical perspective of natural dye

The art of dyeing is as old as human civilization. Archaeological evidence reveals early dyeing practices dating back to 4000 BCE (Kulkarni, 2025) [5] . The use of natural dyes in silk has been deeply rooted in many traditional cultures across the globe and Indians are considered as the pioneers in the field of natural dyeing (Sarkar et al., 2023) [6] . Ancient civilizations in India, China and Egypt used plant parts, insects and mineral sources to dye the fabrics in vibrant hues. In 2600BC the first ever natural dye was found (Bishal et al., 2023) [7] . Some of the countries like France, Holland and Germany began the cultivation of dye plants as an industry from 16 th century. Until 1856 when the first synthetic dye was created, people are using the natural sources like plants, insects, animals, and minerals to prepare the dye. Natural dyes were one of significant trade commodities for centuries including most of the nineteenth century (Fereday, 2003) [8] . Use of dyestuffs in China starts from the year 2, 600 BC. The use of cochineal in the textile industry of Mexico and Peru dates back almost 3, 000 years. Alizarin, purpurin and indigo that are used in Chinese Yanghai textiles were identified in the Late Bronze Age. Prehistoric discoveries of textiles in Europe document the use of alizarin and purpurin from the 4 th century BC (Kramell, 2014) [9] . The first natural dye alizarin is a coal tar base dye that was commercially made by Perkin's firm in 1869

(Sarkar et al., 2023) [6] .

Sources of natural dyes:

There is a wide range of sources from where natural dyes can be extracted. Among those sources plant such as indigo, saffron etc., some insects like cochineal beetles, lac insects and animals like molluscs or shellfish along with the microbes such as Pseudomonas, Bacillus, Rhodococcus etc. are well known. Besides these some minerals like ferrous sulfate, ochre, and clay are also the good source opf natural dye (Kadolph, 2008) [10] . Addition to these, agro-waste such as pumpkin skin, almond shell, silkworm excreta, feces of bovine (Sarma et al., 2025) [2] can be utilized as natural sources of dye.

Plant or vegetable-based dyes:

Dyeing of fibers or cloths with plant or vegetable-based dye is an age-old traditional practice. Dyes can be extracted from flowers to the roots of a plant. India is very rich in biodiversity. There are more than 450 numbers of dye-producing plants or vegetables in the country (Bishal et al., 2023) [7] . Among those plants many of them are utilized for dyeing the silk. a) Mulberry leaves: The extract from mulberry leaves produced a brown to yellowish brown colour (Chetia et al., 2023) [11] . b) Turmeric (Curcuma longa): Roots or tuber of the turmeric yields yellow colored dye. That is useful for dying the silk as well as other natural fibers like cotton and wool. etc. It does not produce any health hazards due to it's medicinal property. c) Henna (Lawsonia inermis): Commonly known as as the Egyptian privet or mignonette tree, henna is a wellknown dye. Dye is extracted from the leaves of this plant that imparts orange to reddish tone. It shows excellent compatibility with silk and wool fibers, producing rich color (Bishal et al., 2023) [7] . d) Indigo: It is the king of all-natural dyestuffs and because of the presence of indican (1H-indol-3yl b-Dglucoside) the leaves extract of indigo yields the significant blue hue (Bishal et al., 2023) [7] . Silk can be dyed successfully with Indigo (Gokarneshan, 2022) [4] . e) Indian Madder or manjistha (Rubia cordifolia):

Madder has been traditionally utilized for centuries to produce red color (Tian et al., 2023) [12] . It is a type of flower bearing plant belonging to the Rubiaceae family that yields red colour from its roots on textile fabrics. f) Marigold: The dye can be isolated from yellow or orange colored marigold flower. Its biological sources are Tagetus erecta and Calendula officinalis, from Asteraceae family. The main colouring agent in marigold flowers is lutein that gives yellow to orange hue (Chengaiah et al., 2010) [13] . It can be successfully utilised in dyeing of both wool and silk fibres.

g) Pomegranate: Dyes obtained from pomegranate peel imparts orange to yellow colour. Since it contains around 19% of total tannin content it can be use as mordant in dyeing process. Granatonine present in the pomegranate peel and grains is the main component that imparts color to the substrate (Goodarzian and Ekrami, 2010) [14] . Pomegranate peel extract in addition with turmeric can increase the dyed fabrics' light resistance capacity. It is applicable for dying silk, cotton and synthetic fibres. h) Saffron: The dye is produced from dry stigmas of the Crocus sativus plant. It is commonly known as the "saffron crocus". It imparts a vivid yellow color in the dyed material. It may color cotton, silk, and wool directly (Korankye, 2010) [15] . i) Wood apple or Bael (Aegle marmelos): It is plant from Rutaceae family which bears yellow green fruit with hard outer covering. Leaves of this plant is use to extract the dye which imparts daisy yellow to lemon yellow color (Sarma et al., 2025) [2] . j) Annatto (Bixa orellana): It is a perennial evergreen plant that bears globular red-brown spiky seed pods.

The outer coating of the seed is used to extract the dye that gives orange to reddish color (Meena et al., 2013) [16] . k) Teak: Teak leaves offer a viable option for natural dye that can be utilized to dye the silk and other natural fibres. It has a longstanding history of being used as a natural dye in textile industry in the countries like India, Laos, Indonesia, and Thailand (Kusumawati et al., 2021) [17] . Anthocyanins, an organic substance belonging to the flavonoid group is the natural colouring agents that present on teak's leaves (Roengthanapiboon et al., 2024) [18] . l) Harad (Terminalia chebula): The seed pericarp can be utilized as a source of dye (Onial et al., 2015) [19] . It is also known as myrobalan and can be use as natural mordant. m) Tamarind seeds: Yellow to brown colored dye can be extracted from the leaves and seeds of tamarind (Tamarindus indica). It can be utilized to dye the cotton and silk fabrics.

Insect-based dyes: Natural dyes sourced from insects have significant role in textile coloration, particularly in providing vibrant red shades. a) Tyrian purple: It is considered as one of the earliest known animal base dyes extracted from marine molluscs belonging to snails of the Muricidae family, commonly found in the Levantine Sea (Koren, 2005) [20] . It is a highly expensive dye since to produce a little amount of color thousands of molluscs are required. It is known for its rich violet hue and was traditionally used to dye the garments of royalty and symbolized power and nobility. This dye can be applied to different natural fibers like silk, cotton and wool (Bishal et al., 2023) [7] . b) Cochineal: It is native to Central and South America, particularly Mexico and Brazil (Serrano et al., 2011) [21] . These insect produce a red pigment known as carminic acid, which constitutes about 9-10% of their body mass in the form glyceryl myristate. Carminic acid is especially valued for dyeing natural animal fibers due to its excellent color fastness and strong affinity to protein based textiles (Serrano et al., 2013) [22] . When combined with mordants like aluminum and tin oxide, it yields crimson red and scarlet hues (Khan et al., 2015) [23]. It is used to color the wool and silk from time immemorial. c) Lac Dye: The liquid released by the lac insect (Lauifer lacca) is used to make this color. They impart a red pigment because of the presence of main chemical component laccaic acid (Sharma, 2017) [24] .

Mineral dyes

Mineral dyes are obtained from naturally occurring inorganic substances, including various metal salts and metal oxides. These pigments are typically categorized based on the colors they produce. Some important mineral dyes are (Agarwal and Tiwari, 1989 ; Singh and Parmar, 1998) [25,26] Red pigments a) Cinnabar: Cinnabar also referred as vermillion, a heavy reddish mineral known for its metallic, shiny appearance. [7] .

Blue Pigments a) Ultramarine Blue:

This brilliant blue pigment is obtained by grinding the semi-precious mineral lapis lazuli. In India, it has been prized for its intense color and extensively used in textile dyeing. b) Lapis lazuli: It is a metamorphic rock rich in blue color. Used for blue nuances.

Microbial dyes

With the growing global interest in eco-friendly and sustainable alternatives, microbial dyes have emerged as promising substitute for different dye sources. Specially fungi and bacteria (Joshi et al., 2003) [27] have gained popularity in dye making industry as well as in textile industry for their potential to produce stable, vivid pigments in a sustainable manner (Duran et al., 2002) [28] . Microbial dyeing offers several advantages like renewability and biodegradability along with the potential for large scale production under controlled conditions (Kim, 2024) [29] .

Recent studies highlight the potential of bacterical species like Streptomyces and Pseudomonas for textile dyeing because of their ability to produce vibrant pigments with good color fastness and fabric compatibility (Chen, 2023) [30] . Some of the sources are listed below. a) Pseudomonas spp.: It is a pigment-producing bacteria responsible for producing some soluble pigments like pyocyanin, pyoverdine, pyorubin and pyomelanin. b) Achromobacter spp.: They are gram negative bacteria capable of producing red pigment. c) Bacillus spp.: It is a pigment-producing gram-positive bacteria that yields yellow, brown, orange and pink color. d) Rhodococcus spp.: This versatile genus can be used in bioprocess technology, bioremediation, pigment synthesis and probiotics in aquaculture. Carotenoids are the pigments that imparts yellow to orange color that is obtained from it. e) Flavobacterium spp.: They are the rod-shaped bacteria characterized by the presence of flexirubin, a unique pigment responsible for the color is the main pigment found in them.

Natural dyes from agro-wastes

As the demand for natural dyes continues to grow, the limited availability of conventional sources has driven the interest towards alternative and more sustainable resources. Among these, agro-wastes-the byproducts of agriculture and allied activities have gained significant attention as potential raw materials for natural dye extraction. Agro-waste refers to a wide range of residues leaf behind after different processes. Many of these contains natural pigments such as tannins, flavonoids, carotenoids etc., which can be use to extract the natural dye. This approach not only supports waste management but also aligns with sustainable and green chemistry principles. a) Pumpkin skin: The dried peels of yellow pumpkin can be utilized for preparation of natural dye. Cotton and silk fabric can be dyed with pumpkin skin extract that imparts yellow color (Karthikeyan and Vidya, 2020) [31] . b) Almond shell: Almond (Prunus dulcis) shell can be used as natural dyes with the metallic mordants which yields rose, cinnamon, brown and burgundy/reddish colors that can be effectively used in wool fiber (Erdem et al., 2014) [33] . Silk can also be dyed with almond shell extract (Deepali and Shraddha, 2017) [34] . c) Feces of bovine: Bovine feces contain lignin components which is a part of the dye that possibly pertains colour to the fiber (Rattan et al., 2008) [35] . Depending on the medium used olive to beige color can be obtain from it (Sarma et al., 2025) [2] . d) Silkworm excreta: Silkworm excreta represent a unique agro-waste with potential as a dye source of sericulture origin. can be used for the preparation of natural dye. It is rich in chlorophyll and carotenoids that yields yellowish brown colour (Vila et al., 2018, Tang et al., 2024) [36,37] .

Trends in silk dyeing with natural dyes

In the rapidly evolving textile industry, silk continues to hold a timeless appeal due to its luxurious texture, luster and strength. However, with increasing concerns about environmental sustainability and pollution, there has been a notable shift in dyeing processes used in silk production. Among the most significant developments is the revival and innovation of natural dyeing techniques. Natural dyeing, once a widespread traditional practice, is making a strong comeback in modern textile design. Historical sources of natural dyes such as indigo, madder, turmeric, lac etc. are regaining importance due to their ecological compatibility. Designers and textile producers are increasingly aligning natural dye palettes with contemporary fashion trends. A recent trend in natural dyeing is the use of agro-waste and underutilized botanical resources starting from the onion peels to silkworm excreta. These are being successfully utilized in silk dyeing. These waste materials, previously discarded, are now upcycled into valuable dye sources.

 Eri silk can be effectively dyed with Aegle marmelos, Bixa Orellana, Brassica oleracea, Curcuma longa, Spinach oleracea, Lacifer lacca, Strobilanthes cusia, Areca catechu, Phaseolus vulgaris and feces of bovine.

Use of natural dyes to dye the silk fabric is economically feasible and sustainable (Sarma et al., 2005) [2] .  Silk can be colored with Basella alba fruit extract that produces different light shades with good light and washing fastness. Dyeing of silk with this fruit extract gives a mordant-free dyeing solution (Balakrishna, 2024) [38] .  A lichen Parmotrema perlatum is a promising natural dye that yields purple colour can be used for sustainable silk dyeing (Roychowdhury et al., 2024) [39] .  A wide range of colors can be achieved on the silk fabric by using onion peel (Allium cepa) extract with different type of natural mordants lemon peel, dry gooseberry, pomegranate etc (Meenakshi et al., 2023) [40] .  Brown colored dye obained from the Syzgium cumini flower can be successfully utilized to color the silk (Santhi and Kowsalya, 2021) [41] .  Andaman satinwood leaves, golden shower pods, neem bark, sappan, acacia bark and burma padauk bark can be use to dye the eri silk yarns that imparts trendy stylish color and also adds excellent level of UV protection property to the silk (Rungruangkitkrai et al., 2020) [42] .  Sophora flower extract is a good natural dye for silk fabric that exhibits good rubbing, washing and perspiration fastness (Yan et al., 2018) [43] .  Beautiful fast pinks and red colours can be obtained from Caesalpinia sappan, the native Indian brasilwood tree, while kapila, Mallotus philippinensis produces bright yellow on silk (Greenfield, 2005) [44] .

To enhance consumer confidence and marketability, products dyed with natural dyes are now being certified by eco-labels such as GOTS (Global Organic Textile Standard) and Oeko-Tex. These certifications ensure that silk fabrics are dyed using safe, non-toxic processes under socially responsible conditions, as sustainability becomes a global priority, such certification adds commercial value and opens up international market opportunities for naturally dyed silk.

Challenges in adopting natural dyes for silk dyeing Natural dyeing of silk has gained renewed attention due to rising environmental concerns and the demand for sustainable alternatives to synthetic dyes. Despite of its historical roots and aesthetic value, the commercial application of natural dye in textile dyeing industry faces numerous challenges, including issues of color fastness, scalability, availability of raw materials and standardization of processes.  One of the primary drawbacks of natural dye is their poor color fastness property which makes them less durable and limiting their application in textile industry (Yusuf et al., 2017) [45] . Natural dye often lacks uniformity, leading to issues such as fading, bleeding or color changes upon exposure to light, washing, perspiration etc.  Natural dyes are typically derived from natural sources like plants, insects etc. and their availability largely depends on season, region, climate ect. causing supply chain issues and difficulty in meeting industrial demand. Compared to synthetic one, natural dyes often require large amounts of raw materials to produce a small amount of colorant. This not only increases the cost but also makes the process resource-intensive (Sun et al., 2021) [46] .  Despite of the advancement in different natural dye extraction methods, scaling of these methods for industrial application remains as a big challenge to the textile industry that requires extensive optimization and validation (Kim, 2024) [29] .  Natural dyes offer a relatively narrow color palette, mostly comprising earthy tones, browns, yellows and some blues. The inability to easily achieve bright or neon shades limits design freedom for textile designers and restricts natural dyes' competitiveness in a fashiondriven market.  To improve color fastness and shade range, natural dyes usually require mordants. Some mordants like copper, chromium or tin salts are toxic and pose ecological as well as health hazards. The widespread use of harmful mordants can negate the eco-friendly benefits of natural dye.

Future prospects

The use of natural dyes in silk dyeing is gaining momentum as the world moves towards more sustainable and ecofriendly choice. With the increasing awareness about the negative impacts of synthetic dyes on health and environment, natural dyes are emerging as a safer alternative. Though challenges remain, due to the innovation of different processing methodes and use of plant-based mordants, that improves color fastness and consistency, there is a ray of hope in upscaling the use of natural dye in textile industry. Now-a-days people are aware of different functional properties of product or materials like UV protection which affects the purchase fabric goods such as coats, scarves, hats and dresses of customers. In addition to being eco-friendly, natural dyes are having UV protection and antibacterial properties which makes it more valuable for the textile industry (Rungruangkitkrai et al., 2020) [42] . If the silk yarns and silk goods can be dyed with natural dyes that are having UV protection properties it will increases the value of silk in global textile market.

Conclusion

The art of silk dyeing is undergoing a thoughtful transformation. With the revival of traditional wisdom and the fusion of scientific innovation, natural dyes are once again becoming a viable and desirable option for silk coloration. As the textile industry redefines its priorities towards environmental health and ethical practices, natural dyeing stands at the forefront of sustainable silk production, bridging the gap between tradition and modernity.

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