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Natural dyes will change the face of dyeing industry says Dr Padma S Vankar

Shweta Bhanot Mehrotra

5/10/2017

Dr. Padma S Vankar, Director Academic, Axis Colleges, Kanpur, and an Ex-Principal Research Scientist, Facility for Ecological and Analytical Testing, Indian Institute of Technology (IIT), Kanpur, shares with us insights on the natural dyes market and its scope. In an emailbased interview with Shweta Bhanot Mehrotra, Dr. Padma talks about the challenges faced by natural dyes and steps undertaken to make it a preferred dye in the market. Excerpts:

Q1. As a research scientist, what is your take on the natural dyes market and its scope?
Keeping in mind the resurgence of natural dyes in the fashion forum and the need to authenticate the natural colorant from the synthetic analogue, the scope of natural dyes is ever expanding. It has a very big market provided the dyers move in that direction and change their mind set. In the coming times, natural dyes will change the face of dyeing industry.

Q2. Why dyers are shying away from accepting natural dyes over synthetic?
There are some challenges in popularising natural dyes. The four main challenges in natural dyeing are dye extraction efficiently, preparation of standardized dye extract, best wash and light fastnesses of the dyed fabrics, and how to increase the dye adherence and how to retain the dye on the fabric. These are some of the main issues that need to be addressed in order to improve the fastness properties. A lot of research has gone into this effort as the commercial market seeks best dyed fabric in all textile materials.

While trying to understand the process of natural dyeing and it’s lost galore, it was important to understand what caused the failure. Thus, it was imperative to have a good understanding of the challenges in natural dyeing. Once this was understood, we started working scientifically in the areas of challenges and innovations.

Q3. Can you highlight on the natural dyeing process and innovations undertaken through research?
Natural dyeing is mostly carried out with the help of metal mordants .Use of aluminium, ferrous, copper, stannic and chromium salts have been prevalent. However, the last three metal salts are toxic and cannot be recommended for industrial use. More so, the waste water management would be a major problem. Since the metal acts as a bridging head between the fabric and dye molecule, it plays a vital role in dye adherence to the fabric, particularly in the case of cotton. Silk and wool being proteinaceous also need metal for binding. Either a one step mordant plus dye called Simultaneous Method, or two step mordanting and dyeing method is being adapted.

However, we used biomordants instead of the metal mordants. A plant extract ( Eurya accuminata) which has inherent metal such as aluminium (Al) or any transition metal can be used along with natural dyeing plant and co-extracted. This helped us to completely eliminate metal mordanting step in natural dyeing process. At the same time, we got very good wash and light fastnesses for the dyed fabrics.

When AAS (Atomic Absorption Spectroscopy) analysis of the plant extracts were carried out, the extract of Eurya acuminata DC var euprista Karth leaves were found to contain substantial amount of Al(aluminium).

Innovations brought in natural dyeing process through our research efforts are in the areas of:
  • Improved extraction procedure
  • Less use of Metal Mordants
  • Introduction of use of Enzymes in dyeing
  • Use of Biomordants
  • Innovative Method for dyeing
  • Optimisation of the dyeing procedures

Q4. What has lead to the revival of natural dyes?
 Revival of natural dyes has been for two reasons. These include the harmful effect of synthetic dyes globally and demand for safer natural dyes. After the Ban of Azo dyes in 1997, it has brought back natural dyes in limelight. Slowly and steadily the awareness towards human safety and environmental protection has led people to realise the hazardous nature of synthetic dyes. Some of which have been identified as carcinogenic and mutagenic.
Another major issue is the waste water management in dye houses. Synthetic dyes have serious degradability issues as against natural dyes which are ecofriendly and bio-degradable. Thus, it is important to promote the use of natural dyes, considering the waste water effluents issues in dye houses.

Q5. Do you foresee natural dyes taking over synthetic dyes market in the near future? Will it be sustainable and which industry is expected to take the lead in it?
Natural dyes can never replace synthetic dyes in the dyeing industry. Synthetic dyes market cannot be fully captured. Even if 10% of the demand of dyes could be met by natural dyes, it will be useful and beneficial. The demand for natural dyes has moved from privately-owned boutiques to fashionable chain of shops.
Over the years (1998 to 2017), there has been an uptrend in the manufacturing and marketing of naturally dyed garments.

Q6. Where does India stand in the production and use of natural dyes?
In India, the vast bio-diversity in flora provides different dye yielding plants. These plants have been identified in different regions and being used for textile dyeing. Organised farming of such dye yielding plants is being carried out as cash crops. In Southern India, Indigo (blue colorant) is being grown and in the North East, Maddar ( Rubia) red colorant along with turmeric (yellow colorant) and many others.

 

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