types of dyes is used for colouration of textile materials. if you are a textile student or a textile company owner or a dyeing master in textile company you must be required to know about different types of dyes uses for the colouration of textile goods.

Different dyes have different Properties. dyes work according to the materials. So, different class of dyes is used in textile industry for dyeing of textile materials.

In this guide you can understand about different class of dyes. in this article we will discuss about valuable information regarding different class of dyes.

So, hold your seat and be with the end of guide. You could get valuable information out of it.

lets get started…..

What is textile dye?

A substance that is used to impart colour to substrate. it may be textiles or fibers. textile dye is used to colouration of textile fibre or textile goods.

History of dyes

Types of dyes

We know that, first egyptins people starts dyeing process for textile materials with different dyes. and Egyptian people produced different types of dyes before many year ago.

this dyes is windly used in textile industry. Different oldest dyes are made from natural source such as plants, animals and some dyes are made from natural plants this dyes is called indigo dyes.

In 1869 an artificial dyes was successfully created. Young scientist or chemist name is William parkin is created synthetic dyes. then this dyes is come around the world and this dye are windly used in textile industry and develop the growth of fabric production.

Germans compny also be produced high production of dyes. it is also be stand for high production of dyes. Specially in a textile industry lots of requirement of dyes for dyeing. but synthatic dyes can cause problems because the solution of synthetic dyes is very dangerous for human body as well as environment. So cleaning of solutions or water must be required before drain out side of industry.

So, the wast water is very important to cleaning for environment because wast solutions is very harmful or pollutant around the world. So, cleaning (ETP) process is done with very carefully. Some Chemical or some substance is windly used during textile dyeing process such as alkali, HCl and more.

Concept of dyeing

We know that textile dyes is organic substance and inorganic substance. the tendency of textile dyes is to absorb light and reflect light to show colour. and dye have also tendency to properly soluble in water. this are the best tendency of dyes. that is reson dyes are used for colouration of textile materials.

the basic concepts of textile dyeing is, the interaction between a dye and a fibre (textile materials/textile goods). and it consist several steps. and in textile dyeing process, involved follow terms, such as,

  1. Disogsregation of the dye
  2. Exhaustion – dye uptake
  3. Adsorption – transfer of dye from aquous solution onto fibre surface.
  4. Diffusion – Textile dye is diffused into the fibre.
  5. Fixation – dye is fixed on to the fibre

In textile Industry, Dyeing is done by particular machine such as,

(a) – jigger dyeing machine

(b) – jet dyeing machine

But Different machine is used for colouration of different materials. such as,

• jigger dyeing machine – cellulosic materials (cotton)

• jet dyeing machine – textile goods (polyester materials)

Different Types Of Dyes:

Now, we will discuss about different types of dyes with their properties;

1. Vat dyes

2. Basic dyes

3. Direct dyes

4. Reactive dyes

5. Azo dyes

6. Acid dyes

7. Azoic dyes

8. Sulphur dyes

9. Pigment dyes

10. Mordant dyes

11. Synthatic dyes

12. Disperse dyes

13. Develop dyes

14. Aniline dyes

15. Nitro dyes

16. Anthraquinone dyes

17. Turmeric dyes (Natural dyes)

Vat dye

types of dyes

Vat dye is made from natural plants. So, Vat dye is also called indigo dyes. Vat dye is insoluble in water but soluble by vatting process. Vat dyes is windly used in cellulose materials for dyeing purpose. Vat dye have good overall fastness properties.

Vat dye is not directly use for dyeing process. Vatting is must be required before dyeing. Because vat dye is insoluble in water but it Solubilized by vatting process and then dyeing is done.

Properties;

1. Vat dye are insoluble in water.

2. The particle size of vat dye is very small.

3. Vat dye are Applied in alkaline condition PH 12-14

4. vat dye mostly belong to indigoid, and Anthraquinone class.

5. vat dyes can’t be directly applied on cotton material for dyeing.

6. In vat dyeing process, first need vatting process.

7. First vatting process is done then it can apply on textile materials for dyeing purpose.

8. After dyeing it gives different shade.

9. wet fastness is very good but rubbing fastness is not good.

10. wet fastness is very good around 4-5.

Vatting Process:

It converting insoluble vat dyes into soluble form is known as vatting. It is given more solubility in water. they are reduced to soluble leuco compound. this process is called vatting process. vat dye are more difficult to reduced then sulphur dye. vat dye displays no substantivity towards cellulose but with the help of suitable reducing agent and alkali convert the insoluble vat dye to its soluble leuco form results in change of colour.  Sodium dithionite (work as a reducing agent) they are windly use in vatting. Sodium dithiouite are more popular reducing agent are mostly used in case of vatting process. Dihydropyrane, Na2S2O4.2H2O and hydrose are mostly used in case of vat dyeing.

After Treatment:

After dyeing some pigment particles is present on the surface of materials. this is carryout with the help of detergent at boiling temp. But removing pigment particles is necessary with the surface of the fabric because these treatment gives final or proper shade. Soaping are required for removing pigment particles with the surface of the fabric. Which gives the material final shade and improved the fastness properties typical of vat dye. It gives different type of shade.

Advantage

Excellent light fastness.

• Vat dyes have good stability for dyeing of cellulosic materials.

• High reproducibility, produce full range of colours.

• Produce better shade for blend materials.

• Vat dyes are produced excellent wet fastness.

Disadvantage

• It is give poor rubbing fastness.

• it is expensive /costly process.

• vatting is required before dyeing.

Basic dyes

Basic dye are insoluble in water but Solubility of this dye in water with the presence of glacial acetic acid. basic dyes are synthatic type class dyes. this dyes are windly used in dyeing of synthatic materials. because this dyes have more affinity for synthetic materials. It’s produced bright shade and high tinctorial values. basic dyes are powerful colouring agent. these dyes are also be called Cationic dye.

Properties;

1. Basic dyes are insoluble in water.

2. Basic dyes have good affinity for synthetic materials.

3. Basic dye is synthetic class type dyes.

4. basic dye is produced bright shade.

5. basic dye is a powerful colouring agent.

6. basic dye is also called cationic dyes.

7. basic dyes is produced excellent shade.

8. basic dyeing is comparatively cheap process. and it is a cheap in price.

Mechanism

Solubility:

The Solubility of this dyes is very good with the prences of glacial acetic acid. Normally, basic dyes are insoluble in water but it become soluble with the prences of glacial acetic acid.

Exhaustion:

Basic dyes Exhaustion rate are variable its depends upon the quality of dyes.

Affinity:

Basic dyes have very good affinity towards silk, acrylic, acrylic/cotton but basic dye have not affinity for cellulosic materials. So is also called synthetic class dyes. these dyes are windly apply on acrylic, silk, wool, and also acrylic/cotton materials.

Direct dye

Direct dye are highly soluble in water. direct dye are easily dissolve in water. this dyes are windly used in cellulose materials because direct dye have good affinity for cellulosic materials such as Cotton materials. Dyeing is done Alkaline condition. direct dye is easy and cheap process. But in this process after treatment is required after dyeing for improving shade of dyed materials. direct dye are also be dyed wool, silk, Nylon materials. this dyes gives good fastness property.

Properties;

1. direct dye have good solubility in water.

2. This dye is more useful for cellulosic materials such as cotton as well as proteins fibres such as wool, silk, and nylon.

3. direct dyeing process is not produce proper fastness properties so generally after treatment is required for shade development.

4. direct dyeing process is comparatively cheap compared with reactive dye and also vat dye.

5. Uses Nature of direct dye is anionic.

6. Direct dyeing process is done at low temp.

7. direct dyeing process is not more expensive compared with reactive dyeing process.

Mechanism

The main mechanism of direct dye is when the cellulose materials is immersed in dye bath solutions of direct dye then some important mechanism will occur such as,

  1. Swelling
  2. Adsorption
  3. Diffusion

Direct dye have good affinity for cellulosic materials such as cotton. This is the reason when cotton material is inter in dye bath then first of all fabric start swelling and then adsorption and then diffusion will take place during dyeing.The affinity of direct dye is also contacted with conjugated bonds and Vander wall’s forces. This are very helpful for dyeing.

Eco-friendly direct dye:

In case of eco-friendly direct dyeing process, first, do not use banned azo dyes which liberate harmful amines.

You can use optimized solubilizing group in chromophore to give blance between solubility and substantivity. Dont use exhaust method you can use padding method. Properly recycling of dye bath. recovery of salt in reverse osmosis.

Advantage:

• cheap process, easy to handle, this dyes are given good result on cellulose materials.

Disadvantage:

• After treatment is required for improvement depth of shade.

Reactive dyes

Reactive dye are soluble in water. Reactive dyes are also more stable for cellulosic materials. this dyes have also be high affinity for cellulosic materials as well as for proteins fibres and also be polyamide fibres. this dyes is easy to make a Covalent linkage with the fibres and work as a integral part of fibre. this dye also be use for dyeing of Cotton,wool, and silk materials.

Properties;

1. Reactive dyes are soluble in water.

2. Reactive dyes are  comparatively cheap and best.

3. Easy dyeing methods and it require less time for dyeing

4. It require low temperature for dyeing

5. Reactive dye having good perspiration fastness with rating 4-5.

6. Reactive dyes have very good wash fastness but has moderate rubbing fastness.

7. Reactive dyes have very good light fastness with rating 6.

8. reactive dyes are found in power, liquid and print past form.

9. Reactive dyes are anionic dyes, which are used for dyeing cellulose, protein, and polyamide fibers

10. Dyes have stable electron arrangement and can protect the degrading effect of ultra-violet ray.

Mechanism

Fixation of dye

In reactive dyeing process, the reactive group of dye is directly reacted with terminal OH or -NH2 group of fibre. and its gives strong covalent bond with the fibre. Alkali is also very important role in reactive dyeing. Because alkali create proper PH in dye bath.
In case of reactive dyeing, maintain PH with the help of alkali. If alkali is add in dye bath its creat proper PH in dye bath. In other words, it is also called dye fixing agent.

Washing of dye

If dyeing is completed then washing is  must be required for textile materials because if unfixed dyes persent on the surface of the materials it is easily removed with the help of washing. and it’s also help in wash-fastness.

It is done with the help of hot washing and then again cold wash.and after this soaping is also required for textile materials.

Azo dyes

Azo dyes are Soluble in water. azo dyes are chemically class of dyes and this dyes are organic compound. Azo dyes are contain functional group (N=N) . this dyes are bound to Aromatic ring. these ring are break down with high temp. these dyes are also be use for dyeing of cellulose materials as well as proteins fibres. azo dyes are produced strong colour with good depth of shade on to the materials. Azo dyes are produced Different strong colour such as acid orange 7, direct blue 15, methyl yellow and acid red.

Some azo dyes are harmful for skin but not all azo dyes. this dyes is easy to absorbed on skin during dyeing so doing work with very carefully. Because if azo dyes are contact on skin then it may chances of skin cancer.

Properties;

1. Azo dye is soluble in water.

2. It is a chemical class of dyes.

3. this dyes are chemical class of dyes.

4. this dye are highly organic compound.

5. this dyes are contain azo function group (N=N).

6. It is properly bound to aromatic ring.

7. azo dye are used for the dyeing of cellulose materials as well as polyester materials.

8. this dyes are produced strong colour with good depth of shade on to the materials.

9. this dyes have some important colouring Function property. this is the reason it gives good colour (shade) on materials.

10. this dye gives good effect on cellulosic materials

Acid dyes

Acid dye are highly soluble in water compare to the basic dyes. Acid dyes are windly used for proteins fibres such as wool, silk, acrylic, nylon. Proteins fibres contain Sulphonic acid groups. The function of Sulphonic acid groups is to improve or increase the Solubility in water.

And it’s gives proper dye molecules and this molecules make negative charge and proteins fibres are make positive charge. This both make more interacts to dye property. In this process, some special force is applied during dyeing such as Vander walls force and hydrogen bond. This force is help during dyeing. and get even dyeing.

Properties;

1. Acid dyes are highly soluble in water compare with basic dyes.

2. Acid dyes is properly work on proteins fibres such as wool, silk, nylon.

3. Acid dye have no affinity for cellulosic materials. Hence, acid dye is not suitable for cellulosic materials.

4. Acid dyes is more suitable and profitable for proteins fibres such as silk, wool, nylon and acrylic.

5. Acid dyes are properly ionic in nature.

6. Acid dyes is more react on to the proteins fibres with the help of Vander Waals and hydrogen bonds because it’s formed between fibre and dyes.

7. Light fastness is good in case of acid dye but in case of basic dye light fastness is poor.

8. In case of acid dyes, uses strong acidic to netural pH.

9. Acid dyes is more effective for proteins.

What is role of Ph in acid dye:

In case of dyeing of wool, pH play very important role during dyeing, the role of pH is also depends upon the quality of dyes if quality is not proper then fixation is not properly, I mean, fixation of materials is not good, it may show uneven dyeing occurs on to the materials.

the main function of ph in acid dyeing, it give proper fixsation of dye on to the materials. don’t used low pH and high pH because it increases chances of damage for materials. So maintain pH depend upon materials.

What is role of Glauber’s salt in acid dyeing methods:

Glauber’s salt is play very important role in acid dyeing methods. don’t use more glauber’s salt, it effect rubbing fastness of materials. it is also called levelling agent.

Azoic dyes

Azoic dyes are Contain azo group (N=N). Azoic dyes are synthatic types dyes. Its made in the form of readymade. azo dyes are produced coloured substance by the reaction of two components such as,

(1) Coupling compound (napthol)

(2) Di – azo Component ( salt diazo)

Azoic dyes are Colour Component but it is insoluble in water. and azoic dyes are gives exllent washing fastness property.

Properties

1. Azoic dyes are insoluble in water.

2. Azoic dyes give bright colour.

3. This dyes gives excellent washing fastness.

4. Dyes also give good light fastness.

5. This process is not expensive.

6. Easy to handle.

7. This process is not long process.

8. This dyes are Mostly use for synthetic materials for colouration.

Sulphur dyes

Sulphur dyes are in soluble in water. Sulphur dye are more suitable for cellulosic materials and denim fabric. Sulphur dyes are produced strong deep shade. and this dyes are also produced Different colours such as red, yellow, orange. Sulphur dyes are converted to leco form with the help of dilute aqueous (Na2S) before dyeing. Also be use for production of heavy materials such as rubber materials.it also be used for textile printing process. but it is costly process.

Properties;

1. Sulphur dyes are insoluble in water.

2. Sulphur dyes have no afinity for textile cellulose fibres.

3. Sulphur dyes are converted to leuco form before dyeing with the help of dilute aqueous (na2s).

4. This leuco form is used for dyeing of cellulose materials.

5. Sulphur dyes develop s-s linkage in chemical structure.

6. Sulphur dyes are produced black and brown shade.

7. Sulphur dyes are used and it’s give great results in case of different types of textile printing.

8. Sulphur dyes are insoluble in water.

9. Sulphur dyeing is favourable cost structure.

10. Alkaline condition is required for dyeing.

11. Sulphur dyeing is one of the most popular for black, brown and blue shade production.

Pigment dyes

Pigment is not a dye, pigment is a Chemical substance which is windly use after the pigment dyeing for improving the fastness properties. Pigment easily panetrate on to the materials with the help of binders. So, binder is must be required in pigment dyeing. now a days pigment dyeing is also carried out in lots of industry.

Properties

• pigment dyes have good covering power.

• size particle of this dyes is ranging 0.2 – 0.4.

• Powerful chemical resistance.

• Good dispersion.

• better resistance to tight.

• stability is very good on dyed materials.

Mordant dyes

Mordant dyes are acid dyes in which contains metal atom it can be insert in dye bath during dyeing. Mordant dyes have good affinity for proteins fibres such as silk, and wool.

Mordanting is must be required for synthatic dyestuff, some synthatic dyes are generally in use that required mordanting for proper exhaustion and proper pantration.

this is the reason it produces better shade on to the materials. But if dyes are made from natural plants then mordanting is not required. Mordant dyes required a mordant in their uses, it is easy to deposition in the form of colour.

Properties

• low affinity for textile materials.

• Mordant dyes may be natural or synthetic.

• this dyes are mostly apply on proteins fibre. Such as nylon and acrylic fibre.

• this dye are soluble in cold water.

• Dyeing of textile materials is carry out with the help of mordants.

Synthatic dyes

Synthetic dye are derived from organically. Synthetic dyes are produced wind range of colours. Synthetic dyes are made from Chemical Compound but it can be harmful to human body. For example, synthetic dyes are produced Different types dyes, such as Vat dye, direct dye, basic dyes or more. Water pollution and untreated dye solution is also be harmful for human body and also for environmental. so ETP is must be required for cleaning of dyeing solutions and then drain water base solutions for out of industry.

Properties

1 this dyes give wind range of colour.

2. It is water soluble.

3. It made from chemical compound.

4. This process is not expensive.

5. Etp is must required for this process.

6. Dyes are produce different type of shade/ colour.

Disperse dye

Disperse dye are insoluble in water. This dyes are easy to diffuse in to the fibres Because disperse dye have very small dye particals. Disperse dye are windly used in synthatic materials such as polyester, nylon, and blend materials such as polyester/cotton. disperse dye is given good shade for synthetic materials. Some Chemical substance is used in disperse dye such dispersing agent it’s help to improve the depth of shade on the materials. this dyes have very small dye particals compare to the other dyes, this is the reason to easy to diffuse and easy to panatrate on to the materials. and it gives good shade or good colour on to the synthatic materials. this dyes are also be dyed hydrophobic materials such as nylon, acrylic.

Properties;

1. this dye are insoluble in water.

2. invironment behaviour of this dye is not good.

3. this dye is easy to diffuse in to fibre or materials because disperse dye having very small dye particals.

4. disperse dyeing process is not expansive it is very cheap process.

5. disperse dye colour produce bright and lighter shade.

6. light fastness properties is good rating 4.5-5.

7. some important chemicals is required during dyeing Such as dispersing agent.

8. disperse dyeing is done of synthetic materials with the help of three methods such as high temperature dyeing methods, thrmsole methods and carrier methods.

9. some important chemicals is required during dyeing Such as dispersing agent.

10. it also increase the rate of dye exhaustion power during dyeing. this reason it easily diffuse on to the materials and gives proper shade.

Developed dyes

Developed dyes are made from developer with the help of some after treatment process. The main role of develop dyes are to develop depth of shade on to the materials. For example, develop dyes are “direct dyes.” this dyes is also called developed dyes.

Properties

1

Aniline dyes

Aniline dyes are derived chemically from aniline. Coal – tar distillation product. For example…. inks, dyes and other uses.

Nitro dyes

Nitro dye are Aromatic Compound types dyes. Nitro dyes are produced strong colour with the help of nitro group and hydroxy group. nitro dyes also be contain chlorine and nitro dyes are more stable with the presence of nitro and hydroxy group.

Anthraquione dyes

Anthraquinone dyes are synthatic class types dyes. This dyes are found mostly synthetically. This dyes have carbonyl group (>C=O). anthraquinone dyes are Colourless but red to blue is found from uses hydroxy or amino group. Anthraquinone dyes can be found in natural dyes as well as synthatic dyes. Some dyes are also be know as anthraquinone types dyes such as Mordant, vat and also disperse dye.

Turmeric (natural dyes)

Dyes are made from naturally turmeric dyeing is windly carried out for dyeing of cellulosic materials. these dyes are used in most of the ancient civilization, such as India, Egypt or more.

dyes are mostly used in dyeing, Printing and painting in India. turmeric dyes are extensively used as a Cosmetic for women. Such as Heena, mahandi, and more. dyes are mostly used in food and confectionery. all indian people are used turmeric in food. Because it is very important for indian life.

Turmeric is also be used in textile industry for dyeing purpose. Turmeric powder has ability to dyed cellulose materials. In case of turmeric dyeing first mordanting of turmeric is required then dyeing is done. Its produce pale yellow shade. this dyes is produced good fastness property. and this process is low moderate cost.

Properties;

the use of natural dyes for dyeing, painting and printing.

2. mostly natural dyes are used for dyeing, printing and painting in India.

3. they are extensively used as cosmetics for woman. some examples are heena/ mehadi for decorating the palms and soles young maidens. ‘surma’ to enhance the effect of eye lashes.

4. Natural dye is also used in food and confectionary. ex; saffron, turmeric, kashmiri chilli, and ratanjyot. Because of the wide use, these dyes have become a part and parcel of Indian life.

5. the use of natural dyes for textile dyeing almost disappeared, due to wide range of synthetic colours available, with good fastness properties.

What is Substantivity?

It is define as an attraction that a dye has for a fibre under given dyeing conditions, where by the dye is selectively extracted from an application medium by the fibre.

For example;

Direct dyes have high Substantivity for cellulose fibres.

Direct dye molecules contains some groups such as (-NH2) amino groups which can get attached to cell-OH macromolecule at the hydroxy group of the weak hydrogen bonds.

When a cellulose fibre is immersed in a solution of a direct dye in water, the dye molecules are immediately absorbed by the cellulose macromolecules present on the surface of the fibre.

the dyestuff molecules then diffuse in to the interior of the fibre through the pores in the amorphous region of the cellulose structure.

RSO3Na – RSO3(negative) + Na+ (positive)

Dye class % substantivity or affinity

1. Disperse dye 0%

2. Vat dye 60 – 65%

3. Reactive dye 60 – 65%

4. Direct dye 90 – 95%

5. Naphthol 10 – 20%

What are the Uses of dyes;

1. Vat dyes; vat dyes is used for dyeing of natural fibres or man-made fibers such as,

Cotton, silk, wool (natural fibres) and viscose ( man-made fibers)

2. Basic dyes; similarly, this dyes is also used for dyeing. Such as,

Acrylic, Acrylic cotton, Acrylic wool, wool , jute etc.

3. Direct dye; direct dye is windly use for dyeing purpose of natural as well as man-made fibers. Such as

Cotton (natural), viscose (man-made fibers)

4. Acid dye; this dye is used for dyeing of natural fibers as well as man-made fibers such as,

nylon (man-made fibers), and silk wool (natural fibers)

5. Reactive dyes; it is windly used for dyeing of such type of fibers.

Silk, wool, viscose, nylon.

6. Sulphur dyes;

Cotton, Viscose

7. Disperse dyes;

Nylon, polyester, Acrylic, tri-acetate

8. Mordant dyes;

Cotton, Silk, wool

9. Pigment dyes;

Cotton, and viscose etc

10. Azoic dyes;

Cotton, viscose and more

11. Mineral dye;

Cotton, wool, silk

12. Aniline black dye; Cotton

Frequently Asked Question

1. What are the uses of dyes?

Dyes are mostly uses for colouring, decorating, cleaning of textile materials, wood, food and hair etc. different dyes are use for different materials because different dyes have different properties.

2. What are the most basic categories of textile dyes?

In textile industries, the most basic categories of textile dyes is,

  1. Acid dyes
  2. Direct dyes
  3. Substantive dyes
  4. Mordant dyes

these are the most basic categories of textile dyes.

  1. Acid dyes : these dyes are mostly uses for colouring of wool, silk, and nylon materials.
  2. Direct dyes: these dyes have strong affinity for cellulose (cotton) materials. these dyes are mostly uses for colouring of cotton materials.
  3. Substantive dyes: these dyes have more affinity for cellulose materials. It gives good shade after dyeing.
  4. Mordant dyes: these dye have not good affinity compare with direct and substantive dyes. Mordant dyes required the addition of chemical substances for improving affinity for the materials being dyed.

3. What is the most commonly dye is used?

Reactive dye is most commonly dye because it is widely used for different materials but especially used for cotton or cellulose materials. Some times this dyes are also used for other materials.

4. What are the types of dyes?

Reactive dye, disperse dye, basic dye, vat dye, aniline dye, azo dye, pigment dye, azoic dye, synthatic dye, mordant dye, gel dye, sulphur dye, complex dye and more.

5. Explain the classification of dyes according to the method of application?

You can understand with the help of following figer.

types of dyes
classification of different dyes

6. Explain the classification of dyes according to the chemical structure?

1. Nitro dyes 11. Azoics

2. Azo dyes 12. Indigoid

3. DPM

4. TPM

5. Acridine

6. Quinoline

7. Methine dyes

8. Thiazole dyes

9. Azine

10. AQ

7. What is properties of dyes?

  1. Dye have good quality to produce deep or light shade.
  2. Dye have good fastness property because fastness requirements.
  3. Dye have level dyeing properties or quality.
  4. Easy to handle or easy to use.

A good dyes has the following quality;

  1. Dye have good quality colour.
  2. Dye have good quality to fixed easily on textile materials.
  3. Dye has good fastness properties such, light fastness, wash fastness and more.

Learn more articles

Yarn dyeing process, flow chart of yarn dyeing process?

Fabric dyeing process and fabric dyeing process flow chart.

Basic dye process (review), dyeing of acrylic, wool and jute with basic dye.

Vat dye process, (review) cotton dyeing process with vat dye.

Sulphur dyeing process, (review) dyeing of cotton with sulphur dye.


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