Sunday, January 10, 2010

Indigo Dyeing

Indigo is the primary color of blue jeans , it is an important dyestuff with unique shade of blue color.The dye gives a brilliant and eye catching blue color to the fabric. Indigo has a low affinity  for cotton ,therefore deep blue dyeings are only possible when and oxidation is done several times.The color partially penetrates the yarn , and imparts the surface blue color.The dye then fades gradually fades from the surface of the fabric naturally.
For Manufacturing process of Indigo click here
Natural Indigo
Indigo dye is an important dyestuff with a distinctive blue color. The natural dye comes from several species of plants.A variety of plants have provided indigo throughout history, but most natural indigo is obtained from plants in the genus Indigofera, which are native to the tropics. In temperate climates indigo can be obtained from woad (Isatis tinctoria) and dyer's knotweed (Polygonum tinctorum), although the Indigofera species yield more dye. The primary commercial indigo species in Asia was true indigo (Indigofera tinctoria, also known as Indigofera sumatrana). In Central and South America the two species Indigofera suffructicosa and Indigofera arrecta (Natal indigo) were the most important.
Properties of  Indigo
Indigo is an insoluble dye ,a dark blue crystalline powder, which has to be reduced with suitable reducing agents to make it soluble in water,Indigo works by a chemical reaction called oxidation reduction.Indigo does not dissolve in water. It must be reduced — i.e. the oxygen must be removed— in the presence of alkali by a reducing agent such as thiourea dioxide (thiox), sodium hydrosulfite, Zinc, or bacteria. Upon reduction, indigo becomes colorless and water soluble. In this state, indigo has a high affinity for cellulosic fibers and enters the open spaces of the fiber. The dyed fibers are then exposed to air, which oxidizes the dye molecule back to its insoluble form. The insoluble dye particles are trapped inside the fiber, coloring them permanently blue. Unlike most dyes, indigo forms a mechanical, not
chemical, bond.
A.Indigo is a dark blue crystalline powder that melts at 390°–392°C.
B.It is insoluble in water, alcohol, or ether but soluble in chloroform, nitrobenzene, or concentrated sulfuric acid.
C.The chemical structure of indigo corresponds to the formula C16H10N2O2.


D.The naturally occurring substance is indican, which is colorless and soluble in water. Indican can easily be hydrolyzed to glucose and indoxyl.
E.Mild oxidation, such as exposure to air, converts indoxyl to indigo. 

F.Indigo is a frequency range of visible light, from 440 to 420 nanometers in wavelength, placing it between blue and violet.

Indigo dye
Indigo has despite many other blue dyestuffs kept his popularity. This by no doubt is achieved by the fact that Indigo has a number of properties which have in this combination not yet been achieved by other single dyestuffs.

The main properties are:

• Pleasant colour shade.

• Possibility to achieve by simple repeated dipping, deep marine blue shade.

• Possibility to dye cotton in cold dye bath.

• Competitive in price.

• Possibility to achieve an acceptable colour fastness and the exceptional advantage by repeated washing of fading colour, to keep the colour shade that always a clear, pleasant blue shade result.

Indigo Application
Three basic steps for indigo application are .

1.Dissolving the dye by reduction involving vatting and loosening up.

2.Dyeing from the vat.

3.Oxidising in the air.

Since indigo has a low affinity for cotton, deep blue dyeings are only obtained when dyeing and oxidising are repeated several times.

Dyeing Methods

Five major Indigo dyeing methods for the basic denim are

1- Indigo rope dyeing process

2- Indigo one sheet dye slashing

3- Indigo double sheet dyeing

4- Loop dye 1 for 6 (continuous dye slashing)

5- Loop dye 1for 6 with dyemer (continuous mercerization dyeing and sizing).

Indigo Dyeing on a 20 rope range 
Indigo Dyeing different systems
Indigo rope dyeing some important technical considerations
Dyeing with Indigo - Natural Fermentation Vat

The Blue Denim

Manufacturing Process Of Denim Enter Here
Manufacturing denims Click here
Denim Washing Process :-A step by step guide

New Developments In Indigo Dyeing

Improved system for denim dyeing Click Here
Indigogenius Denim Dyeing System click here

Read Articles on Indigo Denims
Indigo Dye facts Click here
All about developments of Indigo Click here
Garment Washing Techniques for cotton apparels Click here
A-comparative-study-of-different-stone-and-bio-stone-washing-of-denim Click here
Denim Finishes Click here
Bi-stretch denim manufacturing Click Here
Indigo Dyeing on a 20 rope range Click here
Modification on plain loom for Denim Click here
Notes on Yarn for Rope Dyeing in Denim Click Here
Denim Manufacturing Process- the presentation Click here
Proposed Inspection Process for Indigo Dyed Denim Click Here
Manufacturing Process of Denim Click here


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