This post from Hosho is about the use in textiles of organic, eco-friendly dyes made from natural, bio sources.
What are Textile Dyes?
Textile dyes are used for coloring fibers, yarns and fabrics. Dyes are molecules which absorb and reflect light at specific wavelengths to give human eyes the sense of color. There are two major types of dyes – natural and synthetic dyes.
- The natural dyes are extracted from natural substances such as plants, animals, or minerals.
- Synthetic dyes are made in a laboratory. Chemicals are synthesized for making synthetic dyes.
What are the current challenges with textile dyes?
- Hazardous Waste Generation: Since production of dyes needs very toxic and hazardous chemicals, it also generates a hazardous waste, the disposal of which is a major environmental and economic challenge.
- Increasing Transportation Costs: Since dyes are hazardous materials and are produced at central facilities, transportation of dyes from manufacturing plants to textile dyeing and printing facilities is a major cost item and a logistic challenge.
- Increase in Cost of Feedstock or Energy: Petroleum is the starting material for all synthetic dyes and thus the price of dyes is sensitive to the price of petroleum. Also, since synthesis is energy intensive (uses super-heated steam, boiling acids, etc.), the process is sensitive to energy prices and also generates greenhouse gases.
- Toxic and Allergic Reactions: There are occupational safety issues involved since production processes use the toxic and hazardous materials and conditions described above.
How do natural textile dyes solve the problem?
- Minimal Environmental Impact – Because they come from natural sources, natural dyes are not harmful to the environment, which makes it so appealing for consumers. Natural dyes are biodegradable and disposing them don’t cause pollution.
- Renewable – Natural dyes are obtained from renewable sources that can be harnessed without imposing harm to the environment.
- Color pay-off – If you’re going for a soft hue or soothing shade, natural dyes can help you achieve that look.
- Safe – Some natural dyes, such as carmine found in lipsticks, will not cause harm or health problems when ingested.
What are the various types of natural textile dyes?
Natural dyes are dyes and pigments obtained from animal or herbal sources, acquired by using no or minimal chemical treatments. Natural dyes can be classified according to dyeing properties, chemical structure, origin (animal, herbal, mineral), hue or application area (food industry, pharmaceutical industry.
The types of natural dyes currently in use by the global fashion industry are from the following sources:
1.Vegetable sources: Like flowers, barks of trees, leaves, roots, fruits, fruit rinds, stamps etc. This category is also known as Vegetable dyes.
2. Mineral sources: Some of the minerals(ocher) are rich in colouring. They are directly used for colouring of textile.
3. From Animals: Most commonly two natural dyes are drawn from animals comprise Lac and Cochineal.
Before invention of World’s first chemical dyes in 1856 by Dr. Perkin in Germany, everything was coloured with natural dyes. Natural dyes had potential for being used in every surface that has had seen coloured from the ancient times.
Who are the main suppliers for natural textile dyes in large textile manufacturing countries such as India and Bangladesh?
In the Asian textile manufacturing countries, these natural dyes (also called as bio-dyes by some manufacturers) are manufactured by a number of companies, many of them small and small-to-medium enterprises. Many of these companies are led by passionate entrepreneurs who had done the research on their own and have built a small practice.
What are the key challenges with natural textile dyes?
Natural dyes are considered to be an eco-friendly alternative for dyeing of textile
materials, especially natural fiber textiles. However, there are many limitations in
the usage of natural dyes some of which are listed below:
- Tedious Application Process: Natural dyes require a longer dyeing time in comparison with synthetic dyes as very often an additional mordanting step is required. Use of raw dye-bearing materials ensures authenticity but at the same time involves additional dye extraction steps that require time and separate set-up.
- Limited Shade Range: Shade range of natural dyes is limited. Out of the three primary colors—red, yellow and blue—although there are several sources for red and yellow dyes, there is only one major source of the blue dye: indigo.
- Non reproducible Shades: Difficulty in reproducing the shades is another major drawback of natural dyes which is caused by the inherent variations in the proportion of chemical constituents in the natural material and thus in its crude extract depending upon the maturity, variety, and agroclimatic variations such as soil type, region, and so on.
- Fastness Properties: Colorfastness to light and washing are most important parameters to evaluate the performance of a textile and deciding about its end use although colorfastness to rubbing and perspiration are also important especially if it is to be used as apparel.
- Safety Issues: Exploration of new sources for dyes can certainly help in increasing the shade range of natural dyes with good fastness properties. However, extensive research on the safety of these materials to humans and the environment would be needed before propagating their usage as everything of natural origin may not be safe.
- Characterization and Certification Issues: Although dyeing of textile fabrics with dyes obtained from various natural resources has been extensively investigated, little information is available on the identification and characterization of the natural dyes
What are the emerging trends and future possibilities for natural and eco-friendly textile dyes?
- Natural dyes are being used as photo sensitizer for titanium di oxide based dye sensitized solar cells. They are useful to create a new kind of solar cells which can revolutionize the solar cell industry.
- Natural dyes are also used as an anti ultra violet light protector finish. This is preventing skin cancers. They are also being used in water filtration and purification.