Natural dyes are dyes or colorants obtained from plants, invertebrates, or minerals. The majority of natural dyes are vegetable dyes from various plant sources—roots, berries, bark, leaves, and wood and other biological sources i.e. fungi.

The process of natural dyeing has changed due to advancement in technology. Typically, the dye material is put in a pot of water and heated to extract the dye compounds into solution with the water. Then the textiles to be dyed are added to the pot, and held at heat until the desired color is achieved. Throughout history, people have dyed their textiles using common, locally available materials, but scarce dyestuffs that produced brilliant and permanent colors such as the natural invertebrate dyes.

Blue colorants around the world were derived from indigo dye-bearing plants, primarily those in the genus Indigofera, which are native to the tropics. The primary commercial indigo species in Asia was true indigo (Indigofera tinctoria). India is believed to be the oldest center of indigo dyeing in the Old World. It was a primary supplier of indigo dye to Europe as early as the Greco-Roman era.

Here are the steps for process of making natural indigo dye

• Harvesting the indigo: The Indigofera tinctoria is planted during the rainy season in June. By September or October, the plants are ready to be pruned and used for making dye.
• Bundling: The small leaf of Indigofera tinctoria are bundled together using stems as ties. The larger leaf varieties of indigo like Strobilanthes flaccidifolius go straight into the bins.
• Soaking: Water is added to the bins. Heavy stones are used to press the color from the leaves during an overnight soak. The covered bins need to sit for about 24 hours, depending on the weather. After 24 hours the water has ferments overnight and turns blue.
• Removing the bundles: The bundles are drained and removed. The plants are used for fertilizer.
• Adding lime: 2% builders lime Ca(OH)2 is gently mixed into the colored water.
• The Beating Process: The water and lime must be beaten for about 20 minutes – dipping the bowl in and out – oxidizing the mixture. The water changes from murky green to peacock blue to a frothy navy color. When the mixture turns frothy and navy-colored it is almost ready. The “schwa” sound of bubbles breaking is the signal to stop beating.
• Collecting the paste: After the indigo paste precipitated to the bottom of the bin overnight, the brown water from the top is carefully. The paste is then collected by pouring it over mesh (collecting debris) then through a fine cotton cloth. This is natural indigo paste, which can be stored in plastic bins for one to two years and used for dyeing later. 
• Preparing the vat: Dyeing takes place in the green form of indigo which is known, confusingly, as white indigo. The paste is mixed with ash water, fruit sugars or rice whiskey, and left to ferment. After a few days of stirring and adding sugars, it’s ready to dye with.  
•  Tie Dye and Shibori: Tie dye and Japanese Shibori are created by tying, rolling, stitching, and folding white cloth before dyeing. The tied-up portions of cloth remain white while the exposed areas turn blue in the indigo vat.
• Dyeing: Cloth coming out of the white indigo vat has a green appearance but quickly turns blue with oxidation. Creating a light or a dark blue cloth requires multiple dips as indigo platelets are layered onto the cloth or yarn. Different shades of indigo after one or multiple dips in the vat.                                                                  
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Other than indigo several other natural dyes are obtained from various sources. These natural dyes obtained are then used to print through various different styles. One of the most famous printing styles is Dabu Printing from Rajasthan.

Dabu printing is a traditional art and an elaborate process in a unique way of dyeing and printing by which exceptional print fabrics of unique appeal result. This mud-resist hand-block printing is practiced mostly in certain pockets in the state of Rajasthan, India. The appearance of these fabrics is unique for the brilliant floral and thematic patterns in sharp and finely detailed prints of bright and well-chosen hues & designs . The highlight of Dabu printed fabrics is the use of organic colours and vegetable pastes which are eco-friendly, skin-friendly, fast, and retain their brilliance for most of the lifetime of the fabric. Dabu printed sarees undergo a rigorous process that involves a lot of not so easily available and costly natural dyes and vegetable pastes.

It is said that a man who by tradition colored clothes for a living (Rangrej in Hindi), in his trip to the river for water did not notice the mud that had clung to his dhoti at the river bank when he returned. The next day the dhoti was also put in the indigo vat along with the other clothes. When they were put to dry, he suddenly noticed that the spots where the mud had stuck to the dhoti were not colored by the indigo. This gave him the bright idea of experimenting the same now with mud smeared in a pattern over a cloth and the effort bore fruit, since the pattern came out un-dyed while the rest of the cloth got colored with the indigo color. This is believed to be the beginning of Dabu being created for the first time. This characteristic of the mud found there and the water of the river gave birth to a new tradition that was called ‘Dabu’. 

Earlier, Rajasthan province was densely populated with Dabu printing clusters. Now, very few remain to live the legacy. Dabu, derived from the word ‘Dabaana’ meaning press, is a technique of using mud as a resist, to create patterns on indigo dyed fabric. With its main centers in Rajasthan, Gujarat and Madhya Pradesh, this craft flourishes in areas that naturally have sticky clay like soil, easily available in nearby areas. Harda(yellow), Alizarin(red), Indigo(blue) are the most common natural dyes obtained.

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Black and red are the most popular colours produced by block printing of cotton in Rajasthan. The chemistry involved in the production is also discussed in this blog. 

Black colour- Treatment of cotton or silk or wool with harda followed by treatment with iron salt is commonly used to produce black colour either during dyeing or printing. Harda treated fabric followed by subsequent printing with alum is used to produce a variety of shades by subsequent dyeing or printing with other natural dyes. This is available on treatment of fabric with Harda solution. Dry Block print with iron salt solution is often used to produce black outline of the design.

Other shades – Different shades are available on treatment of fabric with harda solution. Dry treatment with alum either by printing or treating the whole fabric with alum solution and dyeing or printing with other natural dye sources. During this operation the metal salt chelated with tannin in harda forms another complex with the natural dye source applied by dyeing or printing process.

For example when harda treated fabric is printed with alum, a complex between tannin of harda and aluminium is formed. When this fabric is treated with alizarin by dyeing process, the alizarin forms a complex with aluminium with the formation of red colour.

DABU PRINTING 

The Dabu process used for dabu printing is as follows:

• First of all Fabric is received from the mills. Based on the order, different sizes are measured and cut based on the fabric. 
• Desizing is done by repeatedly beating the wet fabric against a hard surface (stone). It is frequently kept for a day after such beating so that enzymatic reactions can loosen the size. Next day it is again beaten and so on. This process continues for three days.
• The fabric is then pre-washed and soaked for 24 hours to remove all starch, oil, dust, or any other contaminants.
• After that the fabric is dipped in Myrobalan (Tanning) agent. The myrobalan paste is prepared about three hours in advance by mixing about 2kg paste for 100 m of fabric. After that the fabric is dried in the sunlight.
• After it is dried, then the next process of Dabu is done. Printing paste is made using (Jaggery, Hydrate of Lime, Kali Mitti and Gum. The paste is then spread over coir to give it a base. The printing is done using blocks.
• After that fabric is printed once with a paste of Alum+ Tamarind Seed + Direct dye to distinguish. After that fabric is washed once, then it is dried and then goes for boiling.
• In boiling, the fabric is put in the vat containing boiling water mixed with  Dhauri Ke Phool ( Jaloor)+ Alizarin ( Madder)+ Mahi for 1 hour at 100 degrees Celsius. The fabric is circulated about 5 times using Bamboo Poles. If the color required is dark then some iron water needs to be added.
• Then the Dabu paste is prepared based on the number of fabrics involved at a time for undergoing the batch process.
• The fabric is block printed with dabu, which is a mud resist paste made from clay and guar gum, and sprinkled with saw dust (so the fabric will not stick to itself), and laid to dry in the sun. The dabu mud makes the printed area resistant to dyes, and therefore will remain unaffected when it is later dyed.
• Once the mud is dry, the fabric is immersed in a dye, usually indigo, and again laid to dry in the sun. The printers may repeat the dabu printing on top of the dyed fabric to create further layers of resist and again dye it in darker shades of the dye.
• Finally the fabric is washed to remove all traces of the dabu mud, and reveal the resist area to be the original white (or other colors depending on how many times the fabric was dabu printed). The fabric is again dried in the sun.
• It is then ready to be packaged and sold.

Regional Dabu printing is practiced in three states of India – Rajasthan, Gujarat and Madhya Pradesh.The Chippas (printers) and Neelgars (dyers) are mainly the communities that work hand in hand to make these mud resist fabrics. Skills are passed on from generation to generation, with both men and women participating in the activities based on the region they work in. Interestingly, Rajasthan for example, has only men involved in the process, whereas in Madhya Pradesh, only the women take part in the printing activity.

In the early 21st century, the market for natural dyes in the fashion industry was experiencing a resurgence. Western consumers have become more concerned about the health and environmental impact of synthetic dyes – which require the use of toxic fossil fuel byproducts for their production – in manufacturing and there is a growing demand for products that use natural dyes. Natural dyes are skin-friendly and are non-toxic.