Indians have been considered as forerunners in the art of natural dyeing. Although indigenous knowledge system has been practiced over the years in the past, the use of natural dyes has diminished over generations due to lack of docu mentation and precise knowledge of the extracting and dyeing techniques. As a result, natural dyes are not commercially successful. Presently, all environmentally unfriendly synthetic compounds are used for dyeing textile materials. They are non-biodegradable, carcinogenic and generate water pollution as well as waste disposal problems. Natural dyes provide a reasonable solution to these problems. Thus, it is imperative to develop technology for extraction of natural dyes and for their application on textile materials. In this study, attempt has been made to extract natural dyes from a variety of plants sou rces (such as rhizomes of turmeric, Curcuma longa; fruits of harda, T erminalia chebula; petals of safflower, Carthamus tinctorius; roots of barberry, Berberis lycium etc.) using specific techniques. These dyes were tested for their dyeing potential on different textile materials (cotton, silk and wool). Dyeing was done using three different dyeing techniques (pre-, simultaneous- and post-mordanting) wherein different mordants such as alum, copper sulphate and ferrous sulphate etc., were used to fix dye on to the textile material. A rainbow of natural dyes was obtained with varied shades of each colour. Shade cards were prepared for each dye and the colour obtained varied depending on the type of the mordant applied and the mordanting technique used.
Natural dyes have been used as colourants in food, leather as well as textile since prehistoric times. These dyes are obtained from vegetable and animal matter with no or very little chemical processing. In 1856, cheaper and easily available synthetic dyes were introduced, which resulted in a drastic decline in the usage of natural dyes. However, there has been a revival of interest in natural dyes in the global arena due to their non-polluting, non-carcinogenic and eco-friendly nature [
Natural dyes are well known for producing very uncommon, soothing and soft shades as compared to synthetic dyes. This shift in paradigm in favour of natural dyes is also attributed to the stringent environmental standards imposed by many countries in response to toxic and allergic reactions associated with synthetic dyes [
・ being biodegradable, non-toxic and non-allergic;
・ being environment friendly and aesthetically appealing;
・ employment generation and utilization of wasteland;
・ easy extraction of colors by boiling the plants, berries, leaves, bark or flower heads in water;
・ synthetic dyes such as azo dyes are carcinogenic and can produce toxic and allergic reactions;
・ fabric dyed with natural dyes exhibits higher UV absorption that can result in reduced incidence of melanoma;
・ many natural dyes have antibacterial properties;
・ natural dyes are mostly renewable as most of them are plant based whereas synthetic dyes are petroleum-based that is a non-renewable source of energy. Thus, application of natural dyes instead of fossil fuel (petroleum) based synthetic dyes has the potential of earning carbon credits;
・ the waste generated can be used as bio-fertilizers in some cases such as dyeing with indigo, and as a result there is no waste disposal problem;
・ a wide spectrum of colours by mix and match system can be produced;
・ a small variation in the mordant used or extraction medium or dyeing technique can bring about a drastic change in the colour;
・ natural dyes bleed but do not stain other fabrics except turmeric;
・ natural dyes are moth proof and can replace synthetic dyes in kids garment and food stuff for safety.
However, there are several limitations of natural dyes also some of which are listed below:
・ lack of availability of precise knowledge of extraction and dyeing technique;
・ reproducibility of the same shade is difficult;
・ mordant is required to fix the dye into the fabric;
・ skilled man power is required;
・ expensive and colour and light fastness is low.
Despite several limitations, there has been a trend to revive the art of natural dyeing in recent years. This is largely due to increase in environment consciousness among the general masses worldwide.
India has a rich biodiversity and there are more than 450 plants yielding dyes and pigments [
In this study, the dyeing potential of different natural dyes extracted from varied plants was evaluated on different textile materials. The major objectives were as follows: 1) Extraction of dyes from different plant materials available locally or collected from the regional flora; 2) Application of natural dyes to various textile materials; 3) Study the effect of different types of mordants and mordanting techniques in the dyeing process; 4) To obtain different colours of rainbow on textile using plant dyes and simple, effective, eco-friendly and sustainable methods.
Three textiles made of natural fibers viz., cotton (plant origin) and silk as well as wool (animal origin) were chosen for this study.
A variety of plant sources were explored for their dyeing potential (
Three mordants viz., Aluminium Potassium Sulphate, Ferrous Sulphate, Copper Sulphate were tested for this study.
Shade | Plant | Plant part | Extract | Mordant | Technique | Formic Acid |
---|---|---|---|---|---|---|
Red | Red Sandalwood | Bark | Acidic | Alum | Simultaneous | + |
Red Sandalwood | Bark | Basic | Alum | Simultaneous | + | |
Orange | Madder | Roots | Neutral | Alum | Simultaneous | + |
Madder | Roots | Alcoholic | Alum | Simultaneous | + | |
Red Sandalwood | Bark | Neutral | Alum | Simultaneous | + | |
Yellow | Safflower | Dried Petals | Alcoholic | Alum | Simultaneous | + |
Safflower | Dried Petals | Neutral | Alum | Simultaneous | + | |
Turmeric | Rhizome | Neutral | Alum | Simultaneous | + | |
Turmeric | Rhizome | Neutral | Copper Suphate | Simultaneous | + | |
Harda | Fruits | Neutral | Alum | Simultaneous | + | |
Berberis | Roots | Neutral | Alum | Simultaneous | + | |
Mulberry | Leaves | Simultaneous | - | |||
Blue | Indigo* | Leaves | ||||
Green | Indigo* + Berberis | Leaves Roots | ||||
Indigo* + Peppermint | Leaves | |||||
Violet | Red Sandalwood | Bark | Acidic | Ferrous Sulphate | Simultaneous | + |
Alkanet | Roots | Alcoholic | Alum | Simultaneous | + | |
Jamun | Fruit Pulp | Neutral | Alum | Simultaneous | + | |
Brown-green | Eucalyptus | Leaves | Acidic | Copper Sulphate | Simultaneous | - |
Basil | Leaves | Neutral | Alum | Simultaneous | + | |
Onion peel | Dried Peels | Neutral | Alum | Simultaneous | - | |
Spinach (unboiled) | Leaves | Neutral | Alum | Simultaneous | + | |
Heena | Leaves | Neutral | Alum | Simultaneous | + | |
Hibiscus | Petals | Basic | Alum | Simultaneous | + | |
Hibiscus | Petals | Acidic | Alum | Simultaneous | + |
*For Indigo, different method was used (refer 2.2.6).
Dye extract (3%) was prepared by dissolving 15 gm of dye powder or crushed flower material in 500 ml of distilled water. The solution was then kept for boiling on a hot plate for 30 minutes and after boiling the final volume was adjusted to 500 ml with water. Extraction was done in three different mediums (acidic = pH 2; Basic = pH 8; Neutral = pH 7).
The dyeing recipe followed is given in
Parameters | Dyeing Recipe |
---|---|
Material to liquor | 1:30 |
Dye extract (C) | 3% |
Formic acid | 0.5 ml |
pH | 4 |
Time | 60 min |
Temperature | 85˚C |
% of dye solution to be made (P) Dye (ml) = (W*P)/C (W―weight of cloth; P―% of dye solution to be made; C―% of dye extract) | 30% |
The pre-soaked material was dipped in required mordanting solution for 20 - 30 min at 80˚C. Dyeing was done with natural dye at 85˚C for 40 - 60 min. The material was cold washed and then washed with 1% mild detergent for 5 - 10 min. Finally, the material was cold washed and dried under shade.
The pre-soaked material was put in the dyeing bath. On the weight of material required volume of dye solution, mordant and water was added in the dye bath. At 40˚C, the material was put in the dye bath and 2 - 3 drops of formic acid was added. Temperature was raised to 85˚C and dyeing was done for 60 min. The material was cold washed followed by soaping, washing and drying.
The material was dyed in natural dye at 85˚C for 40 - 60 min and cold washed. The material was put in mordanting solution for 20 - 30 min at 80˚C temperature. The material was dried under shade without washing. Soaping with 1% mild detergent was done for 5 - 10 min and cold washed and then dried under shade.
Indigo cakes were brought from the market and were crushed to form powder. A paste was made by dissolving 15 g of the indigo powder in a small amount of warm water. Hot water (50˚C) was added to the paste and then a few fructose crystals and 1 g of calcium hydroxide was added. The solution was stirred constantly to prevent formation of lumps. The entry of air to the solution was prevented to avoid oxidation of indigo. Again hot water was added on top of the solution and subsequently a greenish murky solution was formed. The solution was left for an hour to settle. After an hour, the solution separated out into two layers. The solution was stirred in an interval of 15 to 20 min for about 3 or 4 times. The processed solution was then used for dyeing textiles. The fabric was dipped in the solution and fabric was dipped several times to increase the intensity of the shade. Finally, the fabric was dried in air and oxidation of the dye gave a blue colour to the fabric. Less number of dip gave blue color whereas more number of the dips imparted indigo color to the fabric. Fabric was air dried for a while after each dip and after the last dip a cold wash was given and the cloth was dried.
A variety of natural dyes are obtained from different plants parts viz., roots, bark, leaf, fruit, bark, seed, flower etc., that produce varied colours such as red, yellow, blue etc. [
Yellow colour dyes are the most common colour found in nature and majority (ca. 90%) are flavonoids. They are known to produce pale shades, less light fastness and fairly good wash fastness e.g., tesu, turmeric, kapila (
colour dyes (e.g., indigo) gives excellent fastness to light and washing (
The efficiency of extraction of coloured components present in plants depends on medium of extraction (aqueous or solvent or acids/alkali), pH of the Medium (acidic/alkali/neutral) and conditions of extraction (temperature, time, material- to-liquor ratio and particle size of the substrate). Optimum conditions of extraction variables are determined through extracting the natural colour component from source material by varying extraction parameters of liquor and measuring the optical density of corresponding coloured liquor by using spectrophotometer.
Also, the gravimetric yield of colour can be measured by filtering the extraction liquor through standard filtration process followed by evaporation of solvent, washing and finally drying to get the purified natural colour. In addition, it is important to note that the amount of dye present in plant varies greatly depending on the season, age of the plants, and some other factors. Natural dyes extracted in three different pH mediums (acidic, neutral and alkaline) have been tested for their dyeing potential using different mordanting techniques and three different mordants. It was observed that for most of the plant dyes extraction was better with alkaline medium.
A dye comprises of two principal groups: the chromophore and auxochromes. Chromophore (usually an aromatic ring) is associated with the colouring property and has unsaturated bonds, whose numbers decides the intensity of colour. The auxochrome helps the dye molecule to combine with the substrate, thus imparting colour to the latter. Although some fabrics such as silk and wool can be colored simply by dipping in the dye, others such as cotton require a mordant. Some natural dyes, such as indigo will give good color when used alone;
these dyes are called direct dyes or substantive dyes. The majority of plant dyes, however, require a mordant or a chemical used to “fix” the color to the textile fabric, and prevent the color from either fading with exposure to light or washing out. These dyes are called adjective dyes such as logwood. By using different mordants, dyers can often obtain a variety of colors and shades from the same dye. Fibers or cloth may be pre-treated with mordants, or the mordant may be incorporated in the dye bath. Mordants can be broadly classified into three types: Metallic mordants (Metal salts of iron, copper aluminium etc.); Tannins (Myrobalan and Sumach); Oil Mordants (mainly used in dyeing Turkey red colour from Madder). The final colour, lustre and colour fastness properties of the dyed fabric are dependant not only on the dye but are also determined by the concentration and type of mordants used. Thus, a mordant is more important than the dye itself. Thus, an ideal mordant will be the one that produce required colour yield at low cost without affecting the physical properties of fabric. It should not cause any noxious effect during processing and the dyed textile material should not have any carcinogenic effect during use. Common mordants are alum (usually used with cream of tartar, which helps evenness and brightens slightly); iron (or copper) (which saddens or darken colors, bringing out green shades); tin (usually used with cream of tartar, which blooms or brightens colors,
especially reds, oranges and yellows), and blue vitriol (which saddens colors and brings out greens shades). In present study, it was observed that alum does not alter the colour of original dye; Copper sulphate elevates the colour and gives greenish hue to the fabric and ferrous sulphate adds blackish hue to the colour and gives the shades of grey and black making colour dark and dull.
Different types of mordant and method of mordanting significantly affect the rate and extent of photo fading. For example, Copper or ferrous sulphate gives high resistance to fading, whereas stannous chloride does not. In comparison, light fastness improves when post-mordanting is conducted with copper or ferrous ion but pre-mordanting is superior in case of stannous chloride or alum [
pH of the dyeing bath can be alkaline, acidic or neutral. There are various reports available on different methods of mordanting on different fibers such as cellulosic, protenic and synthetic for dyeing with different natural dyes. Dyeing of cotton and silk with babool, tesu, manjistha, heena, indigo, marigold etc is reported [
The resistance of a material to change its colour or extent of transfer of its colours to adjacent white materials in touch is referred to as colour fastness. For any textile, it is measured with respect to degree of loss of colour or in terms of a staining scale i.e. the extent to which the colour is passed on to the accompanying white material. Generally, light fastness, wash fastness and rub fastness are measured for testing the efficacy of dyeing of textiles. Light fastness of most natural dyes particularly those derived from flower petals are found to be poor-medium. Yellow dyes showed poor light fastness; reds showed better light fastness followed by blue and black. However, the use of mordants has shown to improve the fastness properties. The pH of washing medium plays a very important role in improving the wash fastness of textiles dyed with natural dyes. Generally, natural dyes show moderate wash fastness. Logwood and indigo dyes showed better wash fastness. Majority of natural dyes exhibited moderate to good rub fastness and does not require any after-treatment.
The intensity of color of dye extracted from the same plant material changes with the pH of the medium. Color of the dye on the fabric was the function not only of the mordant but also of the dyeing technique. From the same plant extract but with different mordants and dyeing techniques, different colors were obtained (Figures 1-7). Blending of the colors can also be done. Best colors were obtained on the silk fabric followed by the wool and lastly cotton. Using different plant dyes the entire rainbow of colours could be created (
We thank Dr. Pratibha Jolly, Principal, Miranda House and PI, DSKC for providing the necessary research facilities and for her constant support and encouragement.
Arora, J., Agarwal, P. and Gupta, G. (2017) Rainbow of Natural Dyes on Textiles Using Plants Extracts: Sustainable and Eco-Friendly Processes. Green and Sustainable Chemistry, 7, 35-47. https://doi.org/10.4236/gsc.2017.71003