Natural Dyes: Properties, Advantages and Disadvantages
What is Natural Dyes?
Natural dyes are non-allergenic, non-toxic and biodegradable. Although natural dye are safe for the environment, skin-friendly and eye-pleasing, they have a very weak bond with textile fiber materials and must be fixed on textile fibers using metallic mordants, some of which are not environmentally friendly. Natural dyes are defined as any dyes, pigments or other substances derived from natural sources such as plants, animals and minerals that are renewable and sustainable organic resources with minimal environmental impact.
Sources of Natural Dyes:
Natural dye are mainly natural resource materials, and these dyes are generally classified based on their source as plant, animal, mineral, and microbial dyes, although plants are the main source of natural dye. Natural dye are sustainable because they are renewable and biodegradable.
Roots, leaves, fruits, flowers and bark can be used as natural dye sources. Different colors are available from each part like sappan-wood gives its branches red, bark brown and roots yellow. Many plant byproducts can also be used to make dyes.
Dyes can be obtained from the dried bodies of insects, for example, lac, cochineal and carmes. Cochineal is a bright red dye produced by insects that live on cactus plants. Carmine and Tyrian purple dyes are derived from cochineal, shellfish respectively.
Mineral pigments include iron buff, iron black, manganese bistre, chrome yellow and Prussian blue.
Natural dye can be extracted from fungi, bacteria and algae which are fast growing and have the potential to be commercially standardized. Chitosan, Trichoderma virens and Alternaria alternata were used to obtain dyes. Natural red dye is produced by Monascus anca and also from the fungus Echinodontium tinctorium. Phycocyanin is a blue pigment extracted from Spirulina plorensis algae.
Classification of Natural dyes
They are classified by various ways namely
(A)Based on sources of origin .Depending on the source of origin, natural dye are of three
- Vegetable/Plant Origin
- Insect/Animal Origin
- Mineral Origin: The most important mineral pigments of various colours are as follows
- Red Pigments
- Yellow Pigments
- Green pigments
- White Pigments
- Black Pigments
(b) Based on solubility natural dye are classed into two groups namely:
- Soluble natural dyes
- Insoluble natural dyes
(c) Based on substantively: natural dye can be classified into two groups:
- Adjective natural dye Substantive dyes can dye the fibrous materials , directly without mordant.
(d) Based on colours formed with various, natural dye can be classed into two groups namely:
- Monogenetic: Produce only one colour irrespective of mordant present in the fibre.Polygenetic natural dyes, produce different colours withdifferent mordant
(e) Based on chemical constitution
- Dihydropyran-based Dyes
Advantages of Natural Dyes
- Minimal impact on the environment: As a natural source, Natural dye are not harmful to the environment. It is very attractive to consumers. Natural dye are biodegradable and disposable They do not cause pollution.
- Renewable: Natural dye are obtained from renewable sources Ensures no harm to the environment.
- Chemical reaction: No or little chemical reaction occurs . Dye preparation time involved.
- Settlement: No settlement issues.
- Natural Shades: If you are going for a soft glow or soothing shade, natural colors can help you achieve that look.
- Safe: Some natural dye, such as carmine found in lipstick, will not cause harm or health problems when consumed.
Disadvantages of Natural Dyes
- Cost: A large quantity of natural dye may be required To dye against a certain amount of fabric Synthetic dyes can be, for example, one gram of cotton Dyed with only five grams of synthetic dye, while natural dyeing gram requires the same amount of dyeing material. Since in that case natural colors are used more Synthetic colors are more expensive.
- Standardization:Difficult to standardize and to blend
- Poor brightness and fastness properties: off color payoff The natural color fades faster. More so, quality May not be as consistent as synthetic dyes can provide
- Availability: Another problem with natural dye is their availability Presence. Because it can be difficult to produce.Availability of raw materials may vary seasonally, Places, and species, where artificial colors may be produced In the laboratory throughout the year.
- Fixation: Inadequate degree of fixation.
- Lengthy dyeing method.
- Reproducibility: Poor reproducibility of shades
- Solubility: Poor solubility in water and tedious extraction Procedures may be required
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