13 Printing with Natural Dyes

K. Sangamithirai

epgp books

 

 

 

OBJECTIVES:

  • To understand and identify the need for natural dyes in printing
  • Enable you to understand process of printing with natural dyes
  • To evaluate the fastness of natural prints

INTRODUCTION

 

Printing is one important processes which add value to the fabric. Printing, is a process for applying colourin a definite pattern. Majority of fabrics used in our daily life are printed. Unlike dyeing where the fabric is coloured throughout, printing is localized application of a dye or pigment to a fabric to generate a pattern or a design.It involves different techniques and methods. An increasing interest on the use of natural dyeshas developed due to the growing concern over environment. But the use of natural dyes for printing is not common.

 

IMPORTANCE OF NATURAL DYES FOR PRINTING

 

There is a growing interest on printing with natural dyes due to the demand on the use of natural substances replacing synthetic colourants. Inorder to avoid the pollution problems caused by the synthetic dyes the textile industry is looking into ways of using natural dyes in commercial dyeing and printing .Although dyeing with natural dyeshas widespread in scientific researches, printingusing natural dyes is limited. Pigment printing is the most economical printingprocess and can be applied to all substrates .

 

NATURAL DYES

 

Natural dyes are the colorants derived from natural resources, i.e. from plants, insects and minerals.Dyeing with natural colourants was practiced from ancienttimes.

 

Based on Origin :Natural dyes can be sorted into three categories: naturaldyes obtained from plants, animals and minerals.

  • Vegetable/Plant dyes: from various plant parts such as flowers, fruits, seeds, leaves, barks, trunks, roots, etc. Most of the natural dyes belong to this category
  • Insect/Animal dye :dyes obtained from exudation of dried bodies of insects namely, Cochineal, Kermes, and molluscs. Lac dye and Tyrian purple belong to this category.
  •  Mineral dye:Various pigments from inorganic metal salts and metal oxides belong to this category of natural dyes.

Based on Structure: NaturalColourants are classified in various ways broadly depending on chemical functional groups (Structure). Most commonly available natural colourants

  • Indigoids,
  • Anthraquinones,
  • Alpha napthoqinones,
  • Flavones,
  • Dihydropyrans

Based on Hue: According to application class, the dyes are arranged according to hues. Such as Yellow, Orange , Red , Blue, Green, Brown and black.

 

Some Sources of different coloured dyes and mordants

 

 

MORDANT

 

A mordant is an element which aids the chemical reaction that takes place between the dye and the fibre, so that the dye is absorbed .Thesecompounds bind the natural dyes to the fabrics.There are three types of mordant:

  Metallic mordants:Metal salts of aluminium, chromium, iron, copper and tinare used.

 

Tannins: Myrobalan and sumach are commonlyused in the textile industry.

 

Oil mordants: These aremainly used in dyeing turkey red colour from madder.The main function of the oil mordant is to form a complexwith alum used as the main mordent.

 

Different mordanting methods

 

Mordanting is the treatment of textile fabric with metallic salts or other complex forming agents which bind the natural mordantable dyes onto the textile fibers. Mordanting can be achieved by either pre-mordanting, simultaneously mordanting or post-mordanting. Different types and selective mordants or their combination can be applied on the textile fabrics to obtain varying colour or shade, to increase the dye uptake and improve the colour fastness behaviour of any natural dye

 

PRINTING PROCESS

 

The process of printing involves several stages in the preparation of the fabric , printing paste, and fixing the impression permanently on the fabric.

 

A typical printing process involves the following steps:

  • Preparation of fabric,
  •  preparation of colors,
  • preparation of printing paste,
  • Printing process
  • drying of fabric,
  • fixing the print,
  • after process treatments.

Preparation of fabric for printing

 

For any type of fabric, thorough preparation is essential for better penetration of prints, maximum colour yield and brilliance.

 

For cellulosic fabrics, desizing, Scouring and bleaching are normally carried out . Wool fabrics are scoured and must be chlorinated to attain good colour yield and to stabilise the fabric during steaming and washing-off after printing. Similarly, silk fabric which is to be printed may be degummed prior to printing

 

For a colouredbackground it is then dyed. The cloth has to be brushed, to free it from loose nap, flocks and dust that it picks up whilst stored. Some fabrics require very careful stretching and straightening on a stenter before they are mounted for the printing process.

 

Preparation of colours

 

Natural dye materials are collected from nature. It may be a plant or animal source. If it is a flower, Blossoms should be in full bloom, berries ripe and nuts mature. The amount of material collected should be twice the that of the fabric weight. The materials should be dried in shade.

 

Preparation of printing paste with natural dye

 

The dye or the pigment used for printing is usually finely dispersed in a printing paste, in high concentration. Printing pastes usually contain a thickening agent, a binder and other auxiliaries such as fixing agents, along with the dye source. The process traditionally starts with the preparation of the paste. The composition of the pastes is more complex and variable, being determined not only by the dye used, but also by the printing technique, the fabric, and the fixation methods applied. Mixing of colour is one the most important aspects to ensure quality of printing. The colour should be added at with all the ingredients and Constant stirring of the paste must be ensured at that time

 

Dye Powder :All the dyes used were first converted to powder form. After gathering the dye source, it is dried and powdered. The powder so obtained should be filtered through mesh fabric. The fine powder of natural dye can used for preparing printing paste.

 

Thickening agents: The thickener is the crucial component of print paste. The purpose of the thickener is twofold. First, the thickener gives the print paste the proper viscosity or flow characteristics, so the colour can be applied uniformly and evenly. Second, it holds the colour in place so that one colour paste can be applied adjacent to another without the colour bleeding onto other. The printing thickeners used depend on the printing technique, the fabric and the particular dyestuff. Typical thickening agents are starch derivatives, flour, gum arabic, guar gum derivatives, tamarind, sodium alginate, sodium polyacrylate

 

Binders: Binder is a chemical which forms a thin layer on the fabric. The colour binds to this layer. Any binder must be relatively soft and flexible in addition to good film forming capacity and stability.

 

An increasing awareness about the realization that the chemical intermediates used in dyeing and printing are also toxic and hazardous to human health as well as to the environment. This has led to the use of non-toxic ecofriendly materials. Natural thickening agents such as Cassia seed gum, Mango kernel gum, starches and tamarind seed are used for natural printing paste nowadays in place of synthetic thickeners.

 

Printing process

 

Printing is the impression of colour on fabric in a definite pattern using printing methods. It is important to strain or sieve all colours before printing in order to free them from lumps, fine sand, and other impurities.

 

Cloths like fine cotton, silk or industrial woven nylon are used for straining. It is usually done by squeezing the colour through filter. Fine sieves can also be employed for colours that are used as hot or are as very strongly alkaline or acid.

 

There are number of printing methods followed in printing industry that uses synthetic dyes. Natural dye printing is carries out in small scale. The printers use a pen like tool or blocks to print natural dye on to the fabrics. However Screen printing method is also now used for natural dye printing.

 

Block printing

 

A typical hand block print had no large, uniform areas of colour but was skillfully built up from many small colouredareas.

 

This process is the earliest, simplest and slowest of all printing methods. A design is drawn on, or transferred to, prepared wooden blocks. A separate block is required for each distinct colour in the design. Fine details, difficult to cut in wood, are built up in strips of brass or copper, which is bent to shape and driven edgewise into the flat surface of the block. This method is known as coppering.

 

Colour is applied on to the block and pressed firmly and steadily on the cloth. The second impression is made in the same way. Care must be taken to see that it registers exactly with the first. Pins at each corner of the block join up exactly, so that the pattern can continue without a break. Each succeeding impression is made in precisely the same manner until the length of cloth is fully printed. The cloth is then wound over drying rollers. If the pattern contains several colours the cloth is first printed throughout with one color, dried, and then printed with the next.

 

Block printing by hand is a slow process. It is, however, capable of yielding highly artistic results, some of which are unobtainable by any other method.

 

Screen-printing

 

Screen printing is by far the most common technology today. A significant characteristic of screen printing is that a greater thickness of the ink can be applied to the fabric than is possible with other printing techniques. This allows for some very interesting effects. Flat (bed) screen printing is used for printing with natural dye .

 

Colourpaste will pass through only in areas where no stencil is applied, thus forming an image on the printing fabric. The diameter of the threads and the thread count of the mesh will determine how much colour is deposited onto the surface. A blade (squeegee) squeezes the printing paste through openings in the screen onto the fabric.

 

AFTERTREATMENT OF PRINTS

 

Fixation

 

Fixing the print will depend on the manufacturer. A common method is to iron on the reverse. For natural dyes, iron on the reverse, and then rinse in alternating temperatures of water with detergent.

 

Fixation may alsobedone by steaming.

 

Some steamers aremultipurpose that it may be used as steamersand also to fix pigment prints by a baking at certain temperature.

 

The fabrics are dried in air and then calendared.

 

Washing-off

 

Efficient washing of printed fabric is critical to success,from both technological and environmental standpoints.It is clearly desirable to minimise the use of water andenergy whilst at the same time attaining good removal ofthickener, chemicals and unfixed dye, which must notstain back onto the fabric.

 

The traditional washing-off methodusing an open soaper for woven goods is still common,but knitgoods are more difficult to handle andformerly were treated by washing in rope form onwinches.

 

TRADITIONAL PRINTSIN INDIA

 

With a printing tradition dating back to ages, India is host to a wide variety of textile arts. Celebrated all over the world and applauded within the nation, the handicrafts sector in India has been one worth boasting about. Different regions boast of different textures, styles and techniques and each has a different method along with a unique output. Each has a distinct style which is easily recognisable when worn.

 

Some of the traditional printingtechniquues adapted in India are listed here.

 

1. Kalamkari or qalamkari is a type of hand-painted or block-printed cottontextile, produced in parts of Andhra Pradesh. There are two distinctive styles of kalamkari art in India .

  • Srikalahasti style, wherein the “kalam” or pen is used for free hand drawing of the subject and filling in the colors, is entirely hand worked.
  • Machilipatnam style use of blocks

 

Dyes for the cloth are obtained by extracting colors from various roots, leaves, and mineral salts of iron, tin, copper, and alum. Various effects are obtained by using cow dung, seeds, plants and crushed flowers to obtain natural dye. Along with buffalo milk, myrobalan is used in kalamkari. Myrobalan is also able to remove the odd smell of buffalo milk. The fixing agents available in the myrobolan can easily fix the dye or color of the textile while treating the fabric. Alum is used in making natural dyes and also while treating the fabric. Alum ensures the stability of the color in kalamkari fabric.

  2. Bagh

 

An indigenous printing technique from Bagh district of Madhya Pradesh. It essentially refers to a technique of block printing by hand where the colours used are absolutely natural.

 

The process includes the use of geometric designs and bright colours, and the chemical properties of the river are used to the maximum benefit to obtain the most unique shades. From cotton, silk, chiffon to bamboo chicks, this process can be carried out on a variety of fabrics. The fabric after removal of starch is made to undergo what is known as the “bhatti process” which includes boiling, drying and subsequently printing.

 

3.  Ajrak

 

A particular kind of block printed shawls from the western states in India where they display designs made using block printing by stamps.

 

Woodblock printing gives rise to very geometric shapes and patterns. Vegetable dyes and other natural dyes are used for the process, and this garment is a symbol of the area’s culture and heritage.

4. Dabu

 

Dabu or daboo originates in Rajasthan and is a beautiful mud resist hand block printing technique. It survived the test of time with some difficulty and is a time-consuming printing technique involving many phases and a great amount of labour.

 

A very complicated process, it involves phases of washing, hand printing, use of mud resist and drying. Plants, flowers and different motifs are core components of this kind of block printing, and the technique is practised in various villages in Rajasthan.

 

5. Gold and Silver Dust

 

Dust of precious metals like gold and silver is used in this age-old technique to give textiles the sparkle of gold. Over the ages, the technique has adopted the use of more affordable metals like mica and chamki.

 

This technique uses of already printed, dyed, and finished textiles as it only involves work on the surface without much permeability.

 

A roghan gum paste with castor oil is used. Two different blocks are used, and through perforations, the gum paste is squeezed in a pattern on the textile. Then the metal dust is sprinkled on top of this to add the necessary amount of shine and glitter.Small dots and dashes comprise most designs.

 

6. Sanganeri

Sanganeri, a kind of block printing that originated in Rajasthan, adorns home decor materials as well as apparel.

 

This involves laying out of the material on tables and then printing using blocks with intricate designs. The fabric is marked before, so that symmetry of design is maintained.

 

Beautiful floral designs with buds, flowers, leaves, mangoes and even jhumkas sometimes are part of the detailed designs on the blocks.

 

7. Bandhani

A tie and dye technique that dates back to the Indus Valley Civilization, bandhani is popular amongst all.

 

The cloth is plucked by fingernails into tiny bindings and then dyed. A design made up primarily of dots of different sizes against a backdrop of bright colours mark bandhani.

 

8. Leheriya

 

A simple dyeing technique popular in Rajasthan, it results in striped textiles in a huge variety of bright colours. Cotton or silk cloth is subjected to resist dyeing.The cloth is tied and folded in a manner that the colour is applied only in a particular pattern on the textile.

 

9. Batik

 

This kind of prints revolve around selective soaking of cloth in a colour and preferentially printing it using wax.

 

The process includes soaking, beating, drawing of patterns, applying of wax and other techniques.

 

A wax-resist dyeing technique, this process is applied to the whole length of the cloth. Either a spouted tool or a copper stamp called cap is used for this.

 

10. Bagru

 

Being popular Jaipur in Rajasthan, the printing technique is laborious but produces exquisite results.

 

Washing, hard dyeing, drying and other parts form the core of the printing process. Blocks are placed from left to right and slammed hard on the fabric. The fabric is dried afterwards. They are then washed and boiled and finally rinsed to get the final product.

 

COLOUR FASTNESS

 

Generally it is assumed that the colour will change according to the textile material and printing process. But innatural dyes this expectation is somewhat high due to the effect of mordant, type of the natural dye extract, binder and fiber type.

 

Fastness is the fundamental requirement that coloured textiles should exhibit, to the conditions encountered during the processes following colouration and during their subsequent usage. The fastness requirements, however, are largely determined by the end-use of dyed fabrics. The important parameter forthe evaluation of natural dyes use in printing processes is fastnessesof the prints for, Light, washing, rubbing, perspirationand light fastnesses.

 

Light fastness

 

Most of the natural dyes have poor light stability as compared to that of the best synthetic dyes, and hence thecolours in historical old textile are often different from their original colours. Fading of colour on the textile occurson exposure to light. This degradation occurs when light breaks chemical bonds in dyes. Sunlight is made up of ultraviolet light, visible light and infrared radiation. While short wave UV causes most of the physical property damagetofibres, it is generally the longer wave UV and visible light that causes dyed textile fade. Poor light fastness ofsome of the natural dyes can be attributed to propensity of the dye chromophore to the photochemical oxidation.

Washing fastness

 

Some of the natural dyes undergo a little change in their hue on washing, this may be due the alkaline nature of thewashing mixture mainly the pH. In general, natural dyes have only moderate wash fastness .

 

In general, the fastness of a colour can vary with the type of dye, the particular shade used, the depth ofshade and the dyeing process and mainly the nature of the washing mixture.

 

Rubbing fastness

 

The extent of rubbing may be influenced by the moisture, as many textiles transfers more color when wet the dry rubbing fastness was slightly better than wet rubbing fastness.

 

CONCLUSION

 

More interest in natural dyes has been mainly manifested as conservation and restoration of textiles withreplacement of synthetic dyes in printing. There is little research anddevelopment work in standardization of printing with natural dyes .Only few attempts have been made on this area therefore there is rapid scope for developments.

 

Natural dyes have the potential for application, in specified areas, to reduce the consumption of some of the more highly polluting synthetic dyes . But we need to understand that it cannot altogether replace synthetic dyes and pigments. They do, however have the potential to replace some of the toxic, sensitizing and carcinogenic dyes and intermediates.

you can view video on Printing with Natural Dyes

REFERENCES

  • Hemalatha Jain, Techniques of Dyeing and Printing,Ane Books Pvt. Ltd, New delhi,2010
  • Ashis Kumar Samantaa&PritiAgarwal , Application of natural dyes on textiles, Indian Journal of
  • Fibre & Textile Research, Vol. 34, December 2009, pp. 384-399
  • https://en.wikipedia.org/wiki/Textile_printing
  • https://texnoteblog.wordpress.com/2013/09/04/textileprinting-