Problems and Aspects of Natural

Dyes

By:

Pragati Kodrikar

Problems and Aspects of Natural Dyes

By: Pragati Kodrikar

What Is Meant By Dye? Dye is a organic chemical compound which is used for colouring the fabric. There are mainly two type Natural dyes Synthetic dyes

Natural Dyes: These types of dyes are mainly extracted from the natural resources. These are from renewable sources. Synthetic Dyes: These types of dyes are prepared from various chemicals, man made materials etc.The importance of color in textile products cannot be under estimated. Colors have fascinated mankind since the down of civilization. Natural vegetable dyes have become a part of human life since time immemorial. Egyptian mummies documents of mughal periods bear evidence to the use of these dyes. Since the introduction of synthetic dyes in the year 1856 the use of natural dye was on the wane. Need of Using the Natural Dye Synthetic dyes have several advantages over the natural dyes like good repeatability of shade and brilliance in color performance. There is again a growing trend all over the world for the natural colorants and the present context of ecopreservation these have got tremendous commercial potential. There are also a growing awareness of their non hazardous nature. Manufacturing of synthetic dyes involve many carcinogenic chemicals and the effluents which are discharged in the river or emitted into the atmosphere results into pollution. National and international awareness about depletion of natural resources, ecological imbalance, pollution problem and our disturbed environment due to the ample usage of hazardous chemicals and particularly synthetic dyes have forced us to think of safer alternative. These factors have brighten the scope of utilization of natural dyes. Synthetic dyes are not only toxic and harmful to human skin but also to our environment. So a ban has been imposed on their use by many European countries. This implies the need to reintroduce the use of natural dyes for dying textiles. Natural dyes are biodegradable and eco-friendly. Growing plants for extracting natural dyes also leads to encouragement to forestation to which ultimately results in greater ecological balance. They are safe and compatible with environment. They also have medicinal and curative properties. Natural dyes are soft in color, cool to eyes and good to skin. The appropriate technical knowledge of color extraction, purification and standardization of dying technique is of immense value in case of natural dye. CLASSIFICATION OF NATURAL DYES Mainly natural dyes are classified by three ways.

According to color

According to chemical structure

According to the source

As per the report of German ministry of food,agriculturs and forestry about 90,000 tonnes dyes can be produced every year. This production of natural dyes requires agricultural lands. It is estimated that about 250-500 millions acres of land will be required to produce about 100 millions tones of plant material needed to produce 1 million tones of natural dyes. This land requirement corresponds to 10-20% of the area cultivated for grain through out the world

Sources of Natural Red Dyes

NAME BOTANICAL NAME PARTS USED MORDANT Safflower Carthamus tinctorious Flower -- Caesalpinia Caesalpinia sappan Wood chips Alum Al Morinda citrifolia Root bark Alum Blood root Sanguinaria

canadensis Roots Alum

Anchusa Anchusa tinctoria Roots Alum

Ladys bed straw Gallium verum Roots -- Cochineal Insect Dried body Alum/tin Kerm Insect Dried body -- Madder Rubia tinctorium Roots -- Red wood Caesalpiniaceae family Wood Alum

Sources of Natural Yellow Dyes

NAME BOTANICAL NAME PARTS USED MORDANT English oak Quercus robur Bark Alum Golden rod Solidago species Flower Alum Teak Tectona grandis Leaves Alum Marigold Tagettes species Flower Chrome Agrimony Agrimonia eupatoria Leaves,stem Chrome Fustic Chlorophora tinctoria Wood Alum

Sources of Natural Blue Dyes

NAME BOTANICAL NAME PARTS USED MORDANT Indigo Indigofera tinctoria Leaves -- Waod Isatis tinctoria Leaves -- Suntberry Acacia nilotica Seed pods -- Pivet Ligustrum vulgare Mature berries after

frost Alum and iron

Water lily Nymphoea alba Rhizones Iron and acid Some Example Of Natural Dyes Vegetable Dyes:

Leaves:peach leaves,mohogany leaves,plum leaves,tamarind leaves Flower:marigold,cosmo flower,parijat Bark:Eugenia jambolana lam Roots:onion roots Fruit:grape skin waste Wood:jack fruit

Animal Dyes:

Lac Cochineal kermes

Minerals: In organic metal salts & metal oxides

PRESENT STATUS OF NATURAL DYES Currently natural dyes are used by Hobby groups Designers Traditional dyers and printers Non-government organization Museums Academic institute and research association/ laboratories Industries USA is a major importer of natural dyes. Total import of coloring matter of vegetable or animal origin of these dyes is about 3500 tonnes per year which works out to be 0.4% of the synthetic dyes Import of natural dyes of EU countries were 5300 tonnes for the year 1999.This accounts for 0.53% of the synthetic dyes.Besides this in many countries natural dyes are produced for local consumption which may be around 1000 tonnes INDUSTRIES PRODUCING NATURAL DYES Allergo Company is one of the major natural dye manufacturing company.It has set a target to replace about one percent of synthetic dyes worldwide. According to their calculations they shall require 0.2% of the total available crop land. The growing of raw materials, development of dying technology to meet industrial standards , the transfer of technology to major textile mills are some of the issues that have been considered in making natural dyes commercially viable alternative to the synthetic dyes. It has developed extraction processes that yield pure liquid dye. Liquids are then converted to the dye powder. The waste material generated in the extraction is used for the recycling project a carbon augment to produce compost. It has also produce the ecofriendly mordant. The company is presently producing only five dyes. These are Osage orange, cochineal, madder ,catch and indigo. Alps Industries is another major natural dye producing company. This company is producing 300tonns of natural dye per year. Recently the company has initiated $1million R&D Project on the production of fully ecofriendly natural dyes. The main objective of this three year R&D is to produce at least 6 fully standardized natural dyes from following raw materials, Pomegranate rind , Harda gallnuts , Catechu , Anatto , Madder ,Ratanjot ,Himalayan rhubarb. Apart from these many company produce only single dyes such as indigo, lac, cochineal , catch etc. ADVANTAGES OF NATURAL DYES

Obtain from renewable sources No health hazards, some times they act as health cure Practically very mild chemical reactions are involved No disposal problems They are un sophisticated & harmonized with nature Lot of creativity is used to use these dyes judiciously They help to provide employment for the rural people & preserve our traditional craftsmanship Application process of these dyes is les costly Growing plants for extracting dye leads to encouragement to forestations leads to the great ecological

balance They are safe & compatible with environment They have medicinal & curative properties They are soft in color, cool to eyes & good to skin. They have higher tinctorial value They are ecofriendly They have better biodegradability

They have higher compatibility with environment It saves energy because of raw materials are not from petroleum products Waste material is used for the manufacture of compost

DISADVANTAGES OF NATURAL DYES Limitations of the natural dyes that were responsible for their decline are

Availability Colour yield Complexity in dyeing process Reproducibility of shade

Technical drawbacks of natural dyes Limited number of suitable dyes Allow only wool,natural silk,linen and cotton to be dyed Great affinity in blending dyes Non standardized Inadequate degree of fixation Inadequate fastness properties Water pollution by heavy metals & large amounts of organic substances Non availability of standard shade cards ,precise & specific ways of applications & standard norms

Cost is high because they can not be mass produce & require about 500 acres of land per kilogram of dye Their fastness properties are also not good because

Weak dye fibre bond between the natural dye & fibre Change in hue due to the breaking of dye metal complex during washing Ionizaiven of the natural dyes during alkaline washing

IMPERATIVES

Knowledge gap Non availability in standard form Shortage of trained dyers Dearth on books on the technology of dyeing Unnecessary adverse publicity being given to the natural dyes

THE AVAILABILITY OF DYE DEPENDS ON

Specialized plant & animal sources Byproducts Chemical synthesis Tissue or cell structure possibly with DNA transfer technology

FUTURE OF NATURAL DYES Several anthraquinones compounds have been identified as secondary metabolites produced by fungi,such principles may be investigated & extended to evolve a biotechnological solution combining the adventage of both natural & synthetic dyes The lost cultivation technique for the staple vegetable coloring matters must be researched in ordered to achieve acceptable shade gamut & fastness properties Natural disperse dyes must be developed for man made fibres In the non toxic areas like food, drugs & cosmetic natural dyes alone can be successfully used. It will be the more fascinating caeerier,if the proper attention is given natural dyes has a bright future further now in is suppressed due to the lack of knowledge about that. PROCESS OF DYEING WITH NATURAL DYES Following are the processes of dyeing with the natural dyes. Dye source Extraction of dye Preparation of fabrics Moderating(for natural fibers only) Dyeing of fabric Warm soaping

Washing shade drying By this way a particular fabric can be dyed with the help of natural dyes Dye source: Dye source may be of any kind like plants, animals, minerals. Extraction of dye: Extracted dye may be in three forms Liquid Paste Powder Among these all liquid & paste contains some chemicals so the reactions can takes place.also they are very difficult to store So in general powder dye is more comfortable to use. Extraction of dye can be done in following mediums Water Alkaline Alcoholic In general following procedure should be followed for extraction of dye Take the dye Dissolve it in the solvent Allow that to evaporate Maintain the particular conditions such as PH, temperatures,time for heating etc. Then filter the solution We obtain the dissolved dye solution in this way.

Shade variation occurs when there is even the slight change in PH, temperature, time ,dye amount, solvent concentrations Moderating: It is a process of producing affinity between the fibres & pigments. The substance doing this is said to be the mordant There are mainly three types of mordants Metal salts or metallic Tannic acid Oil mordant

Moderating is required for the natural fibres only. There are three types of moderating can be done Pre moderating Simultaneous moderating Post moderating

Among these all pre moderating is better as the absorption is better in the same one Dyeing of fabric: It can be done under suitable conditions i.e. PH,temperature,time for dyeing etc.otherwise improper dyeing may takes place After these all soaping, washing,drying should be done to fix the color. Feature of Natural Dye

Natural dye contain both the polar and non polar groups. So it can be suitably used for any types of fabrics polyester attracts nonpolar groups so during dyeing nonpolar groups are active in natural dye. Cotton attracts polar groups so during dyeing the polar groups are active in natural dyes EXAMPLES Dyes suitable for the different fibres Cotton: grape skin waste,marigold,tarmarind leaves Polyester: annoto ,henna, juglone, rattan jot, rhubarb, bhangra Wool: onion skin,cosmos flower Silk: dhavadi flowers, jack fruit,Eugenia jambolana lam,pulm leaves Nylon: annoto, henna ,juglone References

conventions on natural dyes by Dr.M.L.Gulrajani Mrs.Jayalakshmi,journal of textile association Dr.S.Amsamani, journal of textile association Surabhi mahajan, journal of textile association Dr.P.Vennila, journal of textile association Natural dyes @onelist.com

About the Author: Author is student of T.Y. BTech Textile, SGGS, Nanded