Different Types of Vegetable Dyes
Rakibul Islam Khan
Department of Textile Engineering
Ahsanullah University of Science & Technology (AUST)
Email: pl_20in@hotmail.com
Vegetable Dyes
The industrial fur dyeing business started around 200 years ago with vegetable dyes such as logwood, redwood, fustic, or sumach extracts. Mordanting is carried out with iron, chromium, or copper salts. The dyeing process is repeated several times, and between the treatments the fur skins are hung up in a humid room to ensure satisfactory oxidation and laking. Vegetable dyes are seldom used today. Occasionally, metal salts such as those of copper or iron are used for brightening natural hair.
Natural dyes are basically elements of natural resources, and these dyes are generally classified as plant, animal, mineral, and microbial dyes based on their source of origin, although plants are the major sources of natural dyes. Vegetables dyes are the main source of natural dyes. Most natural dyes are extracted from different parts of plants and trees. The vegetable dyes extraction is broadly divided into extraction method and extraction technology. The extraction method of vegetable dyes basically depends on the method in which the dye is extracted. There are mainly four methods used in extraction of natural dyes.
- Aqueous method
- Alkaline method
- Acidic method
- Alcoholic method
Potential dye plants include trees, shrubs and herbs, as well as mushrooms and lichens. The plant components used for dyeing are also very different. It can be the whole plant (e.g. weld), the leaves (e.g. woad), the roots (e.g. madder), the flowers (e.g. dyer’s chamomile), the fruits (e.g. common buckthorn), the bark (e.g. oaks), the semen shell (e.g. Persian nut) or, the skin (e.g. onion). Natural dyes are having wide application in the coloration of most of the natural fibers, e.g. cotton, linen, wool and silk fiber, and to some extant for nylon and polyester synthetic fiber.
Different Types of Vegetable Dyes and Their Chemical Structures
Henna (Lawsonia inermis)
Lawsonia inermis is commonly known as “henna”. It is also called mehndi in native language in subcontinent (Bangladesh, India and Pakistan). Henna is a well branched shrub or, small tree frequently cultivated in many tropical and warm temperature regions of Bangladesh, Pakistan, India, Egypt, Sudan, Iran, Yemen and Kenya. Large-scale cultivation for the sake of leaves that yield dye confined to India, Egypt, Pakistan, Bangladesh and Sudan. Powdered leaves of this plant (aqueous paste) are used as a cosmetic for staining hands and hairs. The picture of plant is given in Figure 1.
Unbroken henna leaves will not stain hand, hair or textile materials. Henna’s coloring properties are due to lawsone, a burgundy organic compound that has an affinity for bonding with protein. Lawsone is primarily concentrated in the leaves, especially in the petioles of the leaf. The structure of the coloring component, Lawsone, is given in Figure 2.
Guava (Psidium guajava) is a low evergreen tree or shrub 6 to 25 feet high, with wide-spreading branches and square, downy twigs, is a native of tropical America. Guava is a tropical and semi-tropical plant. It is well known for its edible fruit. Figure 3 shows guava fruit and its leaves.
The leaves of guava contain many essential oils and so it is used for many purposes like producing anti-microbial finishes, providing anti-diarrheal action, having anti-inflammatory effect, etc. The leaves can also be used for dyeing textiles. Quercetin present in the guava leaves is the chemical that is responsible for having the coloring effect on textile material. The chemical structure of Quercetin is given in Figure 4.
Mango (Mangifera indica) is one of the most popular of all tropical fruits. Mangoes belong to genus Mangifera, which consists of about 30 species of tropical fruiting trees in the flowering plant family Anacardiaceae. It is native tropical Asian fruit and has been cultivated in the Indian subcontinent for over 4000 years and is now found naturalized in most tropical countries. The picture of mango tree is given in Figure 5.
The chemical that is responsible for colour in the mango leaf is mangiferin. Figure 6 is the chemical structure of Mangoferin.
The onion (Allium cepa) is also known as the bulb onion. Onions are often chopped and used as an ingredient in various hearty warm dishes. Onion tissue is frequently used in science education for demonstrating microscope usage. Onion skins can also be used as dyes. The picture of onion is given in Figure 7.
The dyestuff present in onion skin is called Pelargonidin (3,5,7,4 tetrahydroxyantocyanidol). The structure of Pelargonidin is given in Figure 8.
Vegetable dyes are renewable source of coloring materials. Vegetable dyes are sustainable as they are renewable and biodegradable. Besides textiles it has application in coloration of foods, medicine and in handicraft items. Though vegetable dyes are ecofriendly, protective to skin and pleasing color to eyes, they are having very poor bonding with textile fiber materials, which necessitate mordanting with metallic mordants, some of which are not eco-friendly, for fixation of vegetable dyes on textile fibers.
References:
- Natural Dyes for Textiles: Sources, Chemistry and Applications by Padma Shree Vankar
- Handbook of natural dyes and pigments by Har Bhajan Singh and Kumar Avinash Bharati
- Industrial Dyes: Chemistry, Properties, Applications edited by K. Hunger
- Virendra Kumar Gupta, “Fundamentals of Natural Dyes and Its Application on Textile Substrates” DOI: 10.5772/intechopen.89964
- https://www.textileblog.com/natural-dyes-dyeing-process-and-environmental-impact/
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Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. Mr. Kiron is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.
