Dyeing of Silk with Reactive Dyes

This is as per a brochure from CSTRI ( Central Silk Board Bangalore)

Receipe

M:L- 1:30
Dye: X% on the weight of material.
Glauber Salt- 20% of the weight of material ( 1st Stage)
Glauber Salt- 20% of the weight of material (2nd Stage)
Soda Ash- 5% of the weight of material ( 1st Stage)
Soda Ash- 5% on the weight of material (2nd Stage)
Temperature ( Cold Brand)- 50 deg C
Temperature ( Hot Brand) - 60 deg C
pH-9,  Time: 65-75 minutes

 Procedure

Preparation of dye solution:

Dissolve required dye powder in boiling water in a separate beaker/vessel.

Set the dye bath with required quantity of water.
Add dye solution and add 20% Glauber salt and 5% soda ash at 1st stage.
Enter the material and work for 10 minutes.
Add 20% glauber salt and 5% sold ash at 2nd stage and work for 20 minutes.
For Cold brand reactive dyes, work for 45 minutes at 50 deg.
For hot brand reactive dyes, work for 45 minutes at 60 deg.
Take out the material followed by cold wash.
Remove excess water by using hydro extractor.
Dry under shade.


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Chemicals used in Textile Processing-2

1. Bleaching Powder

It is hypochlorite of calcium and sodium. Bleaching powder on treatment with small quantities of dilute acid liberates hyopchlorous acid, whcih can easliy furnish nascent oxygen and thus acts as an oxidizing and bleaching agent. It is used for the following purposes:

1. As an oxidising agent in garment processing
2. For bleaching cotton, linen and wool.
3. In rendering wool unshrinkable.

2. Hydrogen Peroxide, H2O2

Hydrogen peroxide is a colorless, odorless, syrupy liquid in the anhydrous state. It is a powerful oxidizing agent. It destroys the color of some organic compounds and is used in garment and textile industry for bleaching delicate fabrics like wool, straw and silk.

3. Potassium Chlorate KClO3

Potassium chlorate is a white crystalline solid, which is soluble in water. On heating it decomposes to give oxygen. The ease with which it can lose oxygen, it acts as a strong oxidizing agent. It is used for garment printing.

4. Potassium Chromate

Potassium chromate is available in the form of lemon yellow crystals with no water of crystallization. In garment industry it is used as a mordant.

5. Potassium Dichromate

It is available in the form of orange red crystals. It is soluble in water. In neutral or acidic solution, potassium dichromate furnishes nascent oxygen and thus acts as an excellent oxidizing agent. It is used in garment industry as an oxidizing agent and as mordant in dyeing.

6. Potassium Permanganate

It acts as a powerful oxidising agent in neutral, alkaline or acidic solution and hence used in the garment industry as an oxidising agent.

7. Sodium Perborate

Sodium perborate is mainly used as a bleaching agent for a variety of fabrics namely wool, cotton, rayon, linen etc. It is also used as an oxidising agent and dye fixing agent.

8. Sodium Hypochlorite

Sodium hypochlorite liberates hypochlorous acid and thus acts as a powerful oxidizing and bleaching agent. It is used in textile and garment industry for bleaching process.

9. Sodium Bisulfite, NaHSO3

An aqueous solution of sodium bisulfite is obtained when an aqueous solution of sodium carbonate is saturated with sulphurdioxide. It is an important reducing agent and is used as an antichlor after bleaching garments with chlorine.

10. Sodium Hydrosulfite

It is used as reducing and bleaching agent in garment and textile industry.

11. Sodium Metabisulfite

On heating, it decomposes into sodium bisulfite and sulfur dioxide and hence it is an important reducing agent. It is used as an antichlor after bleaching garments with chlorine.

12. Sodium Sulfite

It forms colorless crystals very soluble in water. It is decomposed by dilute mineral acids with the evolution of sulfur dioxide. It is used as mild bleaching agent for silk and woollen fabrics and as an antichlor after chlorine bleach.

13. Sodium Sulfide

Its aqueous solution shows and alkaline reaction due to hydrolysis. It is used for manufacture of sulfur dyes and as reducing agent in garment industry.

14. Sodium Sulfoxylate Formaldehyde

It is also known as Rongalite C. It is a powerful reducing agent and exerts its full reducing action only at high temperatures. It finds extensive application in garment and textile industry for printing and stripping dyed fabric prior to re-dyeing.

15. Sodium Thiosulfate

It is also know as hypo. It is a colorless, crystalline and efflorescent substance. It is used as an antichlor after bleaching garments with chlorine.

16. Stannous Chloride: It is used as mordant in garment dyeing and printing.

17. Dextrin

It is a modified starch prepared by heat treatment of starch in the dry state, with or without the addition of small quantities of chemicals. It is a white powder, and finds extensive use as sizing and finishing agent.

18 Glucose

It acts as a strong and cheap reducing agent in garment industry.


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Chemicals used in Textile Processing-1

1. Acetic Acid

Acetic acid is a colorless and corrosive liquid with pungent smell of its own. It is miscible with water, alcohol and ether in all proportions. Acetic acid is used in garment industry for dyeing purposes.

2. Citric Acid

Citric acid is in the form of colorless, translucent crystals or a white granular to fine crystalline powder. It is used as sequestering agent, as mordanting agent in dyeing and cleansing agent for boiler water.

3. Formic Acid

Formic acid is a colorless and pungent smelling mobile liquid. It is miscible with water, alcohol and ether in all proportions. It acts both as an acid and as reducing agent due to presence of both carboxylic and aldehyde group. Formic acid is used in dyeing wool and cotton fabrics.

4. Hydrochloric Acid, HCl

Hydrochloric acid gas is a colorless, pungent smelling gas with acidic taste. It fumes in moist air and is extremely soluble in water.

5. Nitric Acid, HNO3

Nitric acid is a colorless fuming liquid when pure but may be colored yellow due to its dissociation products mainly nitrogen dioxide. It is a strong acid and acts as a powerful oxidizing agent. Nitric acid is used in the manufacture of dyes.

6. Oxalic Acid, HOOC.COOH.2H2O

Oxalic is a colorless, crystalline solid with two molecules of water of crystallization. Oxalic acid is used in garment and textile industry for the removal of ink stains from cloths and bleaching of straw for hats. Its antimony salts are used as mordant for dyeing and printing.

7. Liquid Ammonia, NH4OH

Ammonia is a colorless gas with characteristic pungent odor and an alkaline taste. It is used as a cleansing agent for removing grease in dry cleaning.

8. Caustic Soda ( Sodium Hydroxide), NaOH

Caustic soda is a deliquescent white crystalline solid, which readily absorbs moisture and carbon dioxide from the atmosphere. It is used for mercerizing cotton.

9. Soda Ash ( Washing Soda), Na2CO3

Sodium carbonate is a white crystalline solid containing water of crystallization. It is used in laundry as washing soda. It is also used for softening water.

10. Sodium Bicarbonate ( Baking Soda), NaHCO3

Sodium bicarbonate is available in the form of white crystals, sparingly soluble in water. It is alkaline in nature.

11. Sodium Silicate 

Liquid alkaline Sodium silicate is mostly used in garment industry as a fixing agent and for rendering the garments fire proof.

12. Trisodium Phosphate, Na3PO4

It is a white crystalline solid soluble in water. It is used as detergent in garment processing.

13. Common Salt

It is used as to exhaust dyeing with direct and reactive dyes.

14. Diammonium Hydrogen Phosphate

It is used in printing paste as an acid liberating agent.

14. Glauber Salt, Na2SO4.10H2O

It is used in dyestuff, textile and garment industry. In textile and garment industry, it is added to the dye bath for cotton fabrics to promote dye exhaustion.

15. Magnesium Chloride

It is a colorless, crystalline deliquescent substance soluble in water. It is used in textile and garment industry for sizing, dressing and filling of cotton and woollen fabrics, for thread lubrication or carbonization of wool.

16. Tatar- Emetic

Potassium Antimonyl Tartarateis known as Tartar-emetic. It is used as mordant in large quantities in garment and textile industry.

17. Zinc Chloride

It is a white deliquescent solid exceedingly soluble in water. The concentrated aqueous solution of zinc chloride dissolves cellulose.

18. Zinc Sulphate ZnSO4.7H2O

It is a crystalline solid very soluble in water. It is used as mordant in printing.

---to be continued---


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Textile Softners

Softness of fabric depends upon several factors, these are:

1.       Composition of the Fiber: The more crystalline region a fiber has, the less soft will be the fabric. Thus viscose is more soft than cotton as it has less crystalline region than cotton.

2.       Softness of Yarn: It depends upon the twist. The higher the twist, the less soft will be the yarn and hence less soft will be the fabric.

3.       Weave: Loose weave give more softness to the fabric than closer weave. Thus a fabric made with satin or twill weave will be more softer than that made with plain weave. 

Chemical softening is done by using chemicals which act as a lubricating agent and permits sliding of the fibers in the fabric. However, washing can eliminate these chemicals. Therefore they are applied during the final stage of the treatment.

The most common type of Chemical Softeners are:

1.       Non Ionic softeners: These are less efficient than anionic or cationic softeners, but they can withstand the effects of hard water. They can also sustain themselves in acid and basic environments and thus are most suitable for normal washing.

2.       Anionic Softeners: These are very good and give the fabric a full hand. However they cannot sustain hard water and acid environment. They can also cause yellowing at certain  temperatures.

3.       Cationic Softeners: They are amongst the best of the softeners. However they can cause dye toning. Also they can affect the color fastness to light.

4.       Silicone Based Softeners: These are insoluble in water and therefore must be applied on the fabric after dissolution in organic solvents. They have good fastness to washing. They create a lubricating film on the surface and give fabric a velvety silky hand.

5.        Reactive Softeners: These products have to be cross linked and provide permanent softness and water repellency.               

Factors influencing the cost of Processing

A very good treatment of the topic is given in this article

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What are Plisse and Burnout Prints

Plissé Prints

The plisse prints are created by application of strong alkali to 100% cotton fabric. The alkali is applied in a pattern. After some time ( usually several minutes) the fabric is washed so that the alkali is removed. This results in the shrinkage of fabric from those areas where alkali is applied. This shrinkage causes puckering in the areas where alkali is not applied. A seersucker type appearance can be given to the fabric by applying the print pattern in parallel stripes. The alkali can be applied using direct or resist methods. 

http://ny-image0.etsy.com

Burn Out Prints

A beautiful "burn out" effect can be created by applying strong mineral acids or acid salts in the selected areas of a cotton polyester blended fabric. The acids will cause cotton to be destroyed and the polyeste rremains. Thus very beautiful lacey designs can be imparted to the fabric. Also in the burn out paste, a disperse dye can be incorporated which will also dye the polyester which burnout is taking place. However, due to the corrosive nature of the process special protections need to be taken.

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Indigo Dyeing using Fermentation Vat

Some Notes on Indigo Dyeing using Fermentation Vat

1. Indigo itself doesn not exist as such in nature. It is easily formed by oxidation of a a part of plant called IndigoFera by exposure to air. 

2. Simply speaking, Indigo itself is a blue solid. It is insoluble in water, acid and alkalies. If Hydrogen is added to it, or chemically speaking it is "reduced" by many reducing agents- It changes to "Indigo White" which is colorless. This indigo white can dissolve in water, in presence of alkalies, to a bright yellow liquid. When Textile substance is dipped in it and exposed to air, white indigo takes up oxygen and get converted into blue coloring matter. 

3. In fermentation method water is made alkaline with the the addition of Lime or Alkali. Then substances are added which can ferment easily in the presence of alkali, for example wheat bran (madder is added to expedite the fermentation). It takes about two to three days to ferment and then indigo is added. This bath can be used for several days or even weeks. Fresh indigo and other ingredients are added from time to time. The color of bath is light greenish yellow in color with a blue or bluish green scum. Goods immersed in this bath turns yellow. When they are taken out and exposed to air, the yellow color quickly changes to blue.

3. The color of the bath is very important. If it is bright yellow, it means too much alkalanity and more indigo should be added. If the color is too dark, it needs more lime or other alkali. 

4. After the color has changed, the goods should be rinsed well in two or three waters. After that should be boiled for several minutes in a soap bath to washoff the loose dyestuff and prevent rubbing. Rubbing can also be prevented by building up deep shades by successively dippings in the moderately weak vats, rather than obtaining the shade once for all. 

Here are some tips (Source)

1. Keep the vat covered. The level of water in the pot should be to the brim.

2. Wet out your fibers well. Any air remianing in the fiber will oxidise the indigo in the vat. 

3. Enter the fiber into the vat very carefully, to avoid any air in the wet. 

4. Always work under the vat. 

5. For greens, dye with indigo first. Then rise well and overdye with alum mordant and any yellow dye ( traditionally Turmeric). For purples, dye the Indigo first, rise well, mordant and dye with any red dye. 

Remember, you can use various chemicals to  reduce the indigo vat. The alkalnity of these chemicals vary from Soda Ash ( Sodium Carbonate), Slaked Lime ( Calcium Hydroxide), Sodium Hydrosulphide to Caustic Soda ( Sodium Hydroxide) in that order(from low to high). 

Sources

http://www.archive.org/stream/dyesdyeing00exmorich/dyesdyeing00exmorich_djvu.txt

http://www.aurorasilk.com/info/indigo_tutorial.shtml

http://www.pburch.net/drupal/?q=node/909

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Types of Dyes used in Handblock Printing

The following is a brief description of the chemical dyes used in handblock printing in India:

Pigment dyes

Pigment colors are mixed with kerosene and a binder. The mixed color can be stored for a few days. The motif is printed directly on white or light-colored ground with a variety of pigment colors. Pigment colors are widely popular today because the process is simple, the mixed colors can be stored for a period of time, subtle nuances of colors are possible, and new shades evolve with the mixing of two or three colors. Also the colors are visible as one prints and do not change after processing. Colors can be tested before printing by merely applying it onto the fabric. The pigment color is made up of tiny particles, which do not dissolve entirely and hence are deposited on the cloth surface while rapid dyes and indigo sols penetrate the cloth.

Rapid fast Colors

In this process, the ground color and the color in the design are printed on white and/or light-colored grounds in one step. The dyes once mixed for printing have to be used the same day. Standard colors are black, red, orange, brown and mustard. Color variation is somewhat difficult and while printing it is not possible to gauge the quality or depth of color.

Discharge Dyes

These dyes are used if you need to print onto a dark background. Medium to dark grounds are dyed on fabric with specially prepared dyestuff . The printing colors then used on the fabric contain a chemical that interacts with the dye. This interaction simultaneously bleaches the color from the dyed ground and prints the desired color on its place. Areas can also be discharged and left white. The primary advantage of this process is that vivid and bright colors along with white can be printed on top of medium and dark grounds. 

    

Napthol

These are two sets of chemicals which upon reaction produce a third chemical essentially colorful in nature. Fabric is dyed in one and later printed with the other. The chemical reaction produces a third color. However, the biggest drawback of this process is that there are just a few chemicals available which produce colors upon reaction.

Source: http://www.aiacaonline.org/pdf/block-printing-extended-documentation.pdf 

See the images of these prints here : http://www.sashaworld.com/learn/learnframe.htm              

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What is Glitter Printing

Glitter Printing

Glitter printing enables the fabric to show glittering granules on the fabric. For this Glitter powder is used.

Glitter Powder is generally PET with size of 1/8" to 1/256". It is cut into square and hexagon shape. It is available in metallic, rainbow, laser and iridescent colors. Generally it comes in 25 kg bag. A typical glitter power substance is heat resistant to 170 degree celcius and is acid and alkaline proof. The picture of the glitter powder is as given below:

To Print, first glitter paste is prepared. Glitter powder is added in the Glitter ink, under stirring slowly to avoid lumb formation. Glitter ink is made of acrylic co-polymer. Then it is screen printed using Bull nose squeegee (You can read an excellent manual on squeegee here.) The mesh size should not be more than 20 T (An excellent premier on mesh size can be read here).

One can get an idea of the prices of the chemicals used for glitter printing here.

Source of Picture: http://www.ampmerch.com


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FAQ about Mercerization

This Article written in early 1900s is a superb treatise on everything about Mercerization:

Here is a list of FAQ that this articles seeks to clarify:

1. Why Mercerization ?

Mercerization was evolved to get over the limitation of silk. It is the high price of silk and low production. On the other hand, a product was needed which could imitate the high lustre, steel-like strength, its attractive smoothness and softness, its elasticity and and its quality of taking the most delicate tints and shades in the dyeing process.

2. What is Mercerization

Mercerization is a process applied to cotton yarn or fabrics which gives to the cotton fiber a silk-like luster, greater strength than ordinary cotton and a greater affinity for dyes.

3. How it is done

The cotton is soaked in strong caustic soda or caustic potash solution for a few moments under stretch and then washing in pure water to remove the caustic.

4. What happens to the structure of cotton during Mercerization

In natural condition the cotton fiber is a flat, twisted, ribbon-like filament. When immersed in caustic solution it swells out and takes on a round and a hair like appearance, and becomes plump instead of flat.

5. What happens to the chemical structure of cotton during Mercerization

The cellulose is changed into hydro-cellulose or cellulose-hydrate.

6. Why mercerized cotton takes dyes so quickly. 

Cellulose cannot be dyed so easily. Hydro-cellulose on the other hand, absorbs almost any kind of dye readily. Mercerised cotton takes dyes so fast, that chemicals are added in the dye bath to check the process in order that the dyes may not enter so rapidly as to render the shading uneven.

7. What is role of stretch during mercerisation.

Stretch causes the luster, the more the stretch the more the lustre. However, after a certain point, the stretch causes a decrease in strength. 

8. How mercerization is done actually ? What are the chemicals added and other process parameters.

9. Apart from Caustic Soda, what other chemicals can be used for Mercerisation, what are their limitations. 

10. Why sometimes Carbon disulphide is added in mercerisation. 

11. Should bleaching be done before or after mercerisation

12. What pre-processes ensure better luster in Mercerisation processes

Please refer to the article.

13. What type of Cottons are suitable for Mercerisation

Longer cottons are more suited to get as much natural luster as possible. Similarly combed cotton lend themselves better to Mercerisation than carded cottons. 

14. What is part Mercerisation. How it is used in produces various fabrics.

Taking a cotton blend, and then mercerising will produce an effect called as crepon effect. Similarly, mercerisation can be used to produce seersucker effect by Mercerising only certain stripes on the warp direction by covering the rest of the cloth by suitable means.

15. How to identify Mercerised Cotton

(This method has not been tried by me. Please take all precautions including consultation from a chemical scientist before attempting)


Mercerized cotton may be determined as follows: A solution is prepared by dissolving 140 gms of potassium iodide in about 475 ml of water. To this solution add 30-60gms of iodine, and mix with another solution made by dissolving 850 gms of zinc chloride in 350 gms of water. The cloth sample should first be soaked in water, immersed in this prepared solution for three minutes, and then rinsed in water. Mercerized cotton will have a deep blue color, while unmercerized cotton will wash out white. The blue of this solution on mercerized cotton will show through quite heavy dyes.

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Weekly Website Review- Dyeman

"There are no bad dyes - only bad dyers" is the punch-line of Batik Oetoro , who are suppliers of textile materials, service and know-how to the artists.

The website is well structured and brimming with information.

Click on dyes and you get to see a colorful assortment of dyes. Move down and you will find the dyeing instructions for that class of dyes. There is also a dye receipe for hand painting of the fabrics. Also dyeing instructions for all possible applications are given. For example the following techniques are explained for acid dyes:

1.Dip dyeing
2.Hand painting - chemical water fixation
3.Hand painting - Drimafix fixation
4.Tie dyeing
5.4 Minutes rapid fixation method
6.Polychromatic printing

Under "Fabric Decorating", some marvellous techniques using dyes such as Devore and Marbelling are given.

Though the site was last updated in 2008, you can get an idea about the cost comparison of the different classes of dyes.

There is also an automatic calculator which convert virtually every weight and volume measurement into teaspoons.
I really love their most comprehensive instructions on natural dyes .
They also have instructions for dyeing silk/viscose blend.
For the curious, they have a list of common names used for chemicals .
For the beginner a summary of dyes is given.
Of course, they have a glossary of terms .

Rapid Dyes

The Rapid dyes are stabilized azoic dyestuffs.

 They are applied to the fibers in one operation.

 Bright full colors are obtained with very good fastness properties.

 These are used for printing backgrounds so that the foreground becomes prominent. Hence these are suitable where large areas of ground need to be colored.

 Rapid dyes are mixed with water and boiled with caustic soda and a gum paste. A receipe for rapid dyes is given here.

The shades in rapid dyes are unpredictable since the color that is mixed is different from the final color.

True colors emerge only after the fabric has been printed and washed in a mild sulphuric acid solution.

Also these dyes should be used on the same day.

Some colors such as pure blacks are extremely sensitive to weather. Similarly red colors in rapid is vibrant in summers and mediocre in winter

How to Dye Using Indian Natural Dyes

To Dye the Fabric with natural dyes, we proceed as follows:

Tanning

1. Take 20% Harda powder on the weight of material.

2. Make into a smooth paste , add about 10 liters of water.

3. Soak the fabric in this bath for 10-15 minutes.

4. Work it well and dry.

5. After drying remove the extra unfixed harda powder by brushing.

Mordanting

1. Take about 200 gms of alum or 50 gms of Potassium Dichromate or 200 grams of copper sulphate accoding to the color desired.

2. Add 20 liters of water

3. Mix well

4. Enter the Harda Treated material into the dyebath and work well

5. Keep of 10-15 minutes

6. Squeeze and wash once in plain water to remove excess of mineral salt.

Developing

Please see the "Developing of Color" Section of the article "How to Print Using Indian Natural Dyes" .  

Defects in Sulphur Dyeing

Defects in Sulphur Dyeing

1. Tendering

Tendering in the fabric takes place because sulphur is converted into sulphuric acid after oxidation which is harmful for the cellulosic fibers. This defect can occur on account of not proper washing of the fabric after dyeing which results in retaining of sulphuric acid on the cloth.

2. Uneven Dyeing and Oxidation Marks

This may occur due to:

a. Lower strength of sodium sulphide

b. Using improper amount of sodium sulphide.

c. Sodium sulphide does not wash off fully after washing.

d. Variation in temperature.

e. If colors are not dissolved properly, or colors are not of good quality

f. If the chemical used for oxidation is not of good quality

g. Fabrics are not worked upon properly at the time of dyeing.


3. Bronziness

This defect normally occurs in heavy shades. Given below are the reasons:

1. More time gap between dyeing and washing

2. Using more of less strength sodium sulphide

3. Using more salt.

4. Oxidiser doesn't get washed off properly during washing

5. Sodium sulphide doesn't get washed off properly during washing.

6. More presence of iron and copper ions in water.


4. Poor colorfastness to rubbing

It depends upon:

a. type of color
b. Lower strength of sodium sulphide
c. Poor absorbency of the fabric
d. Fabric is not washed properly
e. The quality of soap used for washing is not proper
f. Dyeing bath made of iron instead of steel
g. Frequent addition of colors and chemicals
h. Using Cationic finishing agent in finishing also lowers the colorfastness to rubbing
i. Improper color solution, Improper material to liquor ratio etc.

5. Roughness in Fabric

1. Using more amount of sodium sulphide that doesn't get washed off during washing.
2. Heavier shade
3. Improper washing
4. Not using anionic softening agent in finishing
5. Not using wetting agent.

How to Improve Colorfastness in Vat Dyeing

Colorfastness Problems in Vat Dyeing- Reasons and Remedies

Causes of Poor Colorfastness in Vat Dyeing

Frequent addition of colors in the dye bath to match the shade. It disturbs the equlibrium between colors and chemicals.

- Improper oxidation

- Improper washing

- Some peculiar colors such as blue and brown also leads to this defect.

- Hardness in the water used

- Mixing of incompatible colors

- Usage of large quantities of reducing agent and alkali

- Improper temperature

- Improper wringing of the cloth

- Faults in the machine

- Not using essential chemicals such as dispersing agent or leveling agents.

- Dyeing in a finished cloth ( Resin or Silicon Finish)

- Improper preparation of the cloth or thread for dyeing ( Like not removing impurities or size)

How to improve colorfastness in Vat Dyeing

1. Dont frequently add colors during dyeing

2. Ensure proper reduction clearance

3. Ensure proper oxidation

4. Choose right colors and chemicals

5. Control Temperarue

6. Use soft water

7. Add Dispersing or levelling agent as per need

8. Dont redye finished cloths

9. Ensure proper washing after dyeing.

10. Treat the material with small amount of Ammonia and Sodium Hydrosulphite

11. Treat the cloth with large amount of reducing agent and alkali. This method can be resorted to if there is some bleeding in the colors.

Listing Defect in Vat Dyeing

Listing Defect in Vat Dyeing and the Precautions to Prevent the Defect

Listing is the variation in color of centre of the fabric with the selvedge. Some of the reasons for this defect are:

1. Improper batching.
2. Non Uniformity in the selvedge
3. Redyeing of the fabric
4. Foam on the two sides of the jigger.
5. Slippage of the fabric from the roller during dyeing.
6. Shortcomings in the machine such as malfunctioning of guide roll, expander roller or improper squeezing.
7. Improper filteration of the colors, improper circlation of the liquor during dyeing. Difference in temperature of liquor in the centre and at the ends.
8. Mixing of colors which are not properly compatible.
9. Improper singeing

The remedies are:

1. There should not be any mechanical fault in the machine.
2. Take proper care during dyeing, like filter the color solution before using, ensure that all the controlling instrument ( temperature, time) work properly. Circulate the liquor continuously during dyeing.
3. If some shade is not coming out proper, dye with a slighly heavy shade without taking out the earlier color.
4. Join the fabrics of the same width while making a lot.

Natural Dyes and their Application Classes

Natural Dyes and their Application Classes

S. No.	Common Name	Dye Class
1	Indigo	Vat
2	Madder	Mordant/Disperse
3	manjeet	Acid/ Mordant/Disperse
4	Sappanwood	Mordant /Disperse
5	Lac dye	Acid/ Mordant
6	Berberine	Basic
7	Tesu	Mordant/ Disperse
8	Kamala	Mordant/ Disperse
9	Dolu	Mordant/Disperse
10	Gall Nuts	Acid/ Mordant
11	Cutch	Acid/ Mordant/ Disperse

An excellent paper on the status of natural dyes in India can be downloaded from here

Here is a great blog talking about mordanting on wool.

Defects in Dyeing with Reactive Dyes

Defects in Dyeing with Reactive Dyes

Defect: Colors are not fast to washing, Abrasion;Staining in the fabric when transporting from place to the other, water marks on the fabric

Remedy : Wash the fabric with soap and soda ash at right temperature. Adding sequestering agent will yield good results. Treating with Ammonia will also give good results.

Defects in the fabric due to Printing- Need to take out full color

Remedy: Treat the dyed fabric with Sodium Hydrosuphite with 5-10 gm Sodium Hydrosulphite at 75 deg C for 30-45 minutes. Add 5-7 gms Caustic Soda for even removal of colors. The color becomes light yellow or brown after removal. Wash it thoroughly with soap.

The color can also be removed by solution of Sodium Hypochlorite. Treat the fabric with a sodium hypochlorite solution ( 3-5 gms Chlorine) for 20-30 minutes. Keep the pH between 9-10. The fabric is treated with Acetic acid after removal of color to remove chlorine and to neutralise the fabric.

The fabric can be redyed after removal of color

Defect: Bleeding in colors during washing, abrasion

Remedy: Boil the fabric with caustic, Treat the fabric with Hydrogen Peroxide ( 5-10 gpl, 60-70 deg C) to make the color fast.


Defect: The fabric has been dyed in darker shade, uneven dyeing

Remedy: To take out color from the fabric treat it with caustic for 45-60 min at 70 deg C. Thereafter treat the fabric with 10-20 gpl Acetic Acid for 40-60 min at 80-85 deg C.

Defect: Uneven dyeing, marks of water, marks of colors

Remedy: Wash the fabric in soap and redye in a darker shade

Defect : The fabric has become stiff and rough after dyeing

Remedy: Finish after adding right softner

Defect: Color staining of fabric, uneven dyeing

Remedy: Redye the fabric in darker shade.

Defect: Color staining in fabrics of darker shade, uneven undyeing

Remedy: Dye the fabric in Sulphur black

Caution: Please treat a small length fabric to check the effectiveness and any harmful effects before commencing a full treatment.

Common Causes of Dyeing Defects

Common Causes of Dyeing Defects:

It is important that the general precautions should be followed while dyeing a textile material. It is always helpful to keep a record of all the conditions (including temperature, time, conc of color, chemicals, material to liquor ratio) in order to get an even shade in each batch. In general the following are the common causes of dyeing defects across all the categories of dyes:

1. The material is not well prepared for dyeing and printing

a. Material having dead fibres or other defective fibres
b. Left over of Chemicals after bleaching etc.
c. Material not properly desized
d. Material not properly mercerised.
e. Absorbancy of the fabric not proper
f. Sticking of insoluble material on the fibres
g. Impurities are not removed properly
h. Uneven heat treatment.

2.Water Quality not Proper

a. More Hardness of water
b. Water has metal ions such as iron.
c. pH of water not proper
d. Water having more chlorine

3. Due to Shortcomings in making Dyeing Solution

a. Improper weight ratio of colors, material and chemicals.
b. Improper material to water ratio
3. Improper filtering of concentrated colors.

4. Due to Shortcomings in the dye machinery

a. Coming out of Dye liquor during dyeing
b. Defective instruments controlling temperature, pressure speed etc.

An Amazing Site on Textile Processing

This site on textile processing contains all the relevant information that is normally needed for a person in this industry.

As the site says it is a complete guide to textile processing industry. It has articles on textile processing, textile testing, textile development, affluent treatment

I thank Sazid for leading me to to this site through his blog.