**3. Advantages and disadvantages of natural dyes/ colouants**

In the recent years, there has been a trend to revive the art of natural dyeing. This is mainly because in some aspects natural colourants are advantageous against synthetic dyes. Some of these advantages along with some limitations (disadvantages) are listed below:

#### **3.1 Advantages of natural dyes/ colouants**


methods, dyeing process variables, dyeing kinetics and test of compatibility of selective natural dyes have become very important, however the information on which is insufficient. That is why, this chapter is very much relevant to the current need of the textile dyers. An attempt has been made here to give scientific overview on dyeing of textiles with natural

The word 'natural dye' covers all the dyes derived from the natural sources like plants, animal and minerals. Natural dyes are mostly non-substantive and must be applied on textiles by the help of mordants, usually a metallic salt, having an affinity for both the colouring matter and the fibre. Transition metal ions usually have strong co-ordinating power and/or capable of forming week to medium attraction/interaction forces and thus can act as bridging material to create substantivity of natural dyes/colourants when a textile material being impregnated with such metallic salt (i.e. mordanted) is subjected to dyeing with different natural dyes, usually having some mordantable groups facilitating fixation of such dye/colourant. These metallic mordants after combining with dye in the fibre, it forms an insoluble precipitate or lake and thus both the dye and mordant get fixed to become

In the recent years, there has been a trend to revive the art of natural dyeing. This is mainly because in some aspects natural colourants are advantageous against synthetic dyes. Some

i. The shades produced by natural dyes/colourants are usually soft, lustrous and

ii. Natural dyestuff can produce a wide range of colours by mix and match system. A small variation in the dyeing technique or the use of different mordants with the same dye (polygenetic type natural dye) can shift the colours to a wide range or create totally

iv. Unlike non-renewable basic raw materials for synthetic dyes, the natural dyes are usually renewable, being agro-renewable/vegetable based and at the same time

v. In some cases like harda, indigo *etc.,* the waste in the process becomes an ideal fertilizer for use in agricultural fields. Therefore, no disposal problem of this natural waste. vi. Many plants thrive on wastelands. Thus, wasteland utilization is an added merit of the natural dyes. Dyes like madder grow as host in tea gardens. So there is no additional

vii. This is a labour intensive industry, thereby providing job opportunities for all those engaged in cultivation, extraction and application of these dyes on textile/food/leather

viii. Application of natural dyes has potential to earn carbon credit by reducing

of these advantages along with some limitations (disadvantages) are listed below:

new colours, which are not easily possible with synthetic dyestuffs.

consumption of fossil fuel (petroleum) based synthetic dyes.

iii. Natural dyestuffs produce rare colour ideas and are automatically harmonizing.

**3. Advantages and disadvantages of natural dyes/ colouants** 

dyes and related issues.

wash fast to a reasonable level.

**2. Definition of natural dyes/colouants** 

**3.1 Advantages of natural dyes/ colouants** 

soothing to the human eye.

cost or effort required to grow it.

biodegradable.

etc.


Despite these advantages, natural dyes do carry some inherent disadvantages, which are responsible for the decline of this ancient art of dyeing textiles.

## **3.2 Limitation/ disadvantages of natural dyes/ colouants**

