What is Cationic Polyester? A Practical Explanation for Textile Merchandisers

What is Cationic Polyester? A Practical Explanation for Textile Merchandisers

In the Surat synthetic textile market, the word cationic is often used as if it is a fibre name. A trader may say, “This is cationic fabric” or “This is cationic yarn.” Technically, however, cationic polyester is not a completely separate fibre family like cotton, viscose, nylon, acrylic or ordinary polyester. It is usually a modified polyester that has been made dyeable with cationic dyes.

This distinction is important for merchandisers, buyers and students. When we hear the word cationic in the market, we should understand both the trade meaning and the technical meaning. In trade, it usually refers to a synthetic fabric with richer shade, two-tone effect, mélange effect, heather effect or cross-dyed appearance. Technically, it refers to polyester whose polymer structure has been modified so that positively charged dyes can attach to negatively charged dye sites in the fibre.

Table of Contents

1. Meaning of Cationic Polyester
2. How Polyester is Made Dyeable with Cationic Dyes
3. Regular Polyester vs Cationic Polyester
4. Difference Experienced by the Customer
5. Cost Comparison
6. Why Cationic Polyester is Popular in Surat
7. Questions a Buyer Should Ask
8. Conclusion

Visual 1: How regular polyester is modified into cationic dyeable polyester.

1. Meaning of Cationic Polyester

Ordinary polyester is mainly PET, or polyethylene terephthalate. It is strong, durable, crease-resistant and widely used in synthetic fabrics. However, normal polyester does not have natural ionic dye sites. For this reason, it is normally dyed with disperse dyes under suitable temperature and pressure conditions.

Cationic dyeable polyester, often called CDP or cationic dyeable PET, is a modified form of polyester. During polymerisation or chip preparation, special chemical units are introduced into the polyester chain. These units carry anionic, or negatively charged, groups. Because of these negative sites, the fibre can attract and hold positively charged cationic dyes.

In simple language:

\[ \text{Cationic Polyester} = \text{Modified Polyester with Anionic Dye Sites} \]

The name may appear confusing at first. The fibre is called cationic dyeable not because the fibre itself is positively charged, but because it can be dyed with cationic dyes. The fibre contains negative sites, and the dye carries a positive charge. The attraction between the two helps the dye attach to the fibre.

2. How Polyester is Made Dyeable with Cationic Dyes

Regular polyester is made from terephthalic acid or dimethyl terephthalate and ethylene glycol. The polymer chain is hydrophobic and relatively crystalline. This compact structure makes dye penetration difficult unless suitable disperse dyeing conditions are used.

To make polyester dyeable with cationic dyes, a third monomer is introduced. A commonly mentioned modifier is a sulfonated isophthalate compound, such as sodium salt of dimethyl 5-sulfoisophthalate, often abbreviated as SIPM or related terms. This introduces sulfonate groups into the polyester chain.

The important functional group can be represented as:

\[ -SO_3^- Na^+ \]

Here, the sulfonate group \(-SO_3^-\) behaves as an anionic dye site. A cationic dye molecule can be represented as:

\[ \text{Dye}^+ \]

During dyeing, the positively charged dye is attracted to the negatively charged sulfonate site:

\[ -SO_3^- Na^+ + \text{Dye}^+ \rightarrow -SO_3^- \text{Dye}^+ + Na^+ \]

This simple equation explains the commercial usefulness of cationic polyester. The dye is not merely trapped physically inside the fibre; it is also attracted to specific ionic sites. This gives the possibility of bright shades, better dye uptake and interesting colour effects.

Merchandiser's Note: Cationic polyester should be understood as a value-added polyester. Its main purpose is not to make polyester natural or breathable, but to change its dyeing behaviour and visual effect.

3. Regular Polyester vs Cationic Polyester

Point of Difference	Regular Polyester	Cationic Polyester
Basic fibre type	Standard PET polyester.	Modified PET polyester, usually with anionic dye sites.
Common dye route	Usually dyed with disperse dyes.	Can be dyed with cationic/basic dyes depending on fibre type and process.
Colour effect	Generally gives a more uniform solid shade unless special yarns or processes are used.	Can create brighter, deeper, heather, mélange, two-tone or cross-dyed effects.
Polymer structure	More regular and crystalline.	Modified structure; sulfonated units disturb regularity and increase dye receptivity.
Commercial positioning	Commodity to premium, depending on yarn and fabric construction.	Generally value-added and used where visual effect is important.
Best use	Plain solids, basic synthetic fabrics, low-cost polyester constructions.	Fancy synthetic fabrics, two-tone fabrics, mélange effects, fashion sarees, dress materials and value-added surfaces.

Visual 2: Customer-experienced differences between regular polyester and cationic polyester.

4. Difference Experienced by the Customer

For the customer, the main difference is usually not chemistry. The customer experiences the difference through appearance, colour depth, hand feel and perceived richness. Both regular polyester and cationic polyester remain synthetic fibres, but cationic polyester often gives a more visually interesting fabric.

Customer Experience	Regular Polyester	Cationic Polyester
Colour appearance	Can look clean, flat and solid.	Can look brighter, deeper and more brilliant.
Surface character	May look plain unless texture, print or weave is added.	Often gives heather, mélange, linen-like or two-tone appearance.
Hand feel	Depends on yarn type, denier, filament count, twist and finishing.	Also depends on construction; may feel slightly fuller or softer in some commercial fabrics.
Drape	Usually good in filament fabrics.	Broadly similar, though effect fabrics may feel fuller depending on yarn and weave.
Comfort	Low moisture absorption; can feel warm in humid weather.	Broadly similar to polyester. Cationic modification does not automatically make it cotton-like or viscose-like.
Retail perception	May be perceived as basic or premium depending on finish.	Often perceived as more value-added because of shade variation and surface interest.

This is the most practical way to explain it in retail: regular polyester gives economy, easy care and durability. Cationic polyester gives the same broad synthetic base, but with better opportunities for colour depth and visual variation.

5. Cost Comparison

Cationic polyester is usually costlier than comparable regular polyester at the yarn or chip stage because it requires polymer modification, specialty raw materials and controlled processing. However, the final fabric cost story is more interesting. A slightly costlier yarn may still become economical if it replaces yarn dyeing, space dyeing, printing, fancy yarn or more complicated processing.

For example, assume:

• Fabric consumption: 120 grams yarn per metre
• Regular polyester yarn: ₹190 per kg
• Cationic polyester yarn: ₹220 per kg

The yarn cost per metre can be estimated as:

\[ \text{Yarn Cost per metre} = \frac{\text{Fabric grams per metre} \times \text{Yarn price per kg}}{1000} \]

Fabric Type	Yarn Price	Approximate Yarn Cost per Metre
Regular polyester fabric	₹190/kg	₹22.80/m
Cationic polyester fabric	₹220/kg	₹26.40/m
Difference	₹30/kg	₹3.60/m higher

This shows an important buying lesson. A ₹30/kg yarn difference does not always become a very large difference per metre. At 120 grams per metre, it becomes only about ₹3.60 per metre at the yarn level. If that extra cost creates a richer look or avoids another costly process, the cationic route may be commercially justified.

Buying Thumb Rule: For plain solid low-cost synthetic fabrics, regular polyester is usually the better choice. For two-tone, mélange, heather, cross-dyed or richer synthetic fabrics, cationic polyester may justify its premium.

Visual 3: Cost versus value logic for regular polyester and cationic polyester.

6. Why Cationic Polyester is Popular in Surat

Surat is a major centre for synthetic yarns and fabrics. The market is highly responsive to new visual effects, cost-effective fashion surfaces and quick commercial adoption. Cationic polyester fits this environment very well because it allows mills and traders to create visual variety without always depending on expensive yarn-dyed or printed routes.

A common commercial approach is to combine regular polyester and cationic polyester in the same fabric. One yarn may accept the cationic dye strongly while the other behaves differently. This difference in dye uptake creates two-tone or cross-dyed effects. The buyer sees a fabric with depth, variation and surface richness, even though the base is still largely polyester.

This is why the market may use the word cationic as a shorthand for a look. In many cases, the customer is not asking about the polymer chemistry. The customer is responding to the fabric appearance: shaded, rich, textured, mélange or slightly linen-like.

7. Questions a Buyer Should Ask

When a supplier says “cationic,” the buyer should not stop at the name. The word may refer to yarn, fibre, fabric effect or dyeing route. A few simple questions can prevent confusion and wrong comparison.

• Is the yarn actually cationic dyeable polyester or only a cationic-look fabric?
• Is the cationic component in warp, weft or both?
• Is the fabric made with regular polyester plus cationic polyester?
• Is the yarn FDY, DTY, POY, spun polyester or a blended construction?
• What is the denier, filament count, lustre and twist?
• Is the effect obtained by piece dyeing, yarn dyeing, cross dyeing, printing or finishing?
• What are the wash fastness, rubbing fastness and light fastness requirements?

These questions shift the conversation from vague market terminology to measurable fabric specification. This is especially useful when comparing costs, approving shades or explaining value to retail teams.

8. Conclusion

Cationic polyester is best understood as a modified polyester developed for dyeability and visual effect. It contains anionic dye sites that allow cationic dyes to attach to the fibre. This modification can produce bright shades, better colour depth, two-tone effects, mélange appearance and other value-added surfaces.

For the final customer, the most noticeable difference is appearance rather than basic comfort. Cationic polyester does not automatically become breathable like cotton or viscose. It remains a synthetic fibre, but it can look richer and more interesting than a plain regular polyester fabric.

For buyers and merchandisers, the correct decision is not simply “regular polyester is cheaper” or “cationic polyester is better.” The right decision depends on the product requirement. If the fabric is a plain solid, regular polyester is usually sufficient. If the fabric needs shade depth, two-tone effect, heather effect or a premium synthetic look, cationic polyester can be a commercially intelligent choice.

Related Reading on Polyester, Dyeing and Synthetic Fabrics

• Direct Dyeing vs Reactive Dyeing: A Technical, Economic and Ecological Comparison
• How to Determine Fibre Composition in Blended Fabrics
• What is Deco Finish in Synthetic Pattu and Kanjivaram Sarees
• Manufacturing Process of Nylon 6,6

Sources and Further Reading

1. DyStar. Technical material on Cationic Dyeable Polyester. This source explains cationic dyeable polyester as polyester modified with anionic groups during polymerisation, allowing it to be dyed with cationic dyes.
   https://www.dystar.com/wp-content/uploads/2018/01/Carpet-Brochure-7-CDP-single-pagesB.pdf
   
   
2. PolyesterMFG. Cationic Dyeable Polyester: Production and Characteristics. This source discusses the production of cationic dyeable polyester and the role of acidic functional groups in improving dyeability.
   https://www.polyestermfg.com/cationic-dyeable-polyester-cdp-production-characteristics/
   
   
3. Textile Learner. Perception into Cationic Dyeable Polyester. This article provides a textile-oriented explanation of cationic dyeable polyester chips and the use of sulfonated comonomers.
   https://textilelearner.net/perception-into-cationic-dyeable-polyester/
   
   
4. Google Patents. Cationic dyeable polyester masterbatch and related production route. This patent source gives technical background on sulfonated isophthalate units and masterbatch/blending approaches for producing cationic dyeable polyester.
   https://patents.google.com/patent/CN102464872A/en
   
   
5. My Textile Notes. All Posts Index. Used to identify relevant internal reading links on dyeing, fibre composition, synthetic fabric finishing and man-made fibre manufacturing.
   https://mytextilenotes.blogspot.com/p/all-posts.html

General Disclaimer

This article is for textile education and general merchandising understanding only. Actual fibre composition, dyeability, fastness, hand feel, cost and performance depend on polymer grade, yarn type, denier, filament count, spinning route, fabric construction, dye class, processing conditions, finishing, shade depth and end-use requirement. Buyers and mills should verify all technical claims through supplier specifications, laboratory testing and bulk production trials before making commercial decisions.

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Is Turkey Red Same as Alizarin

The answer is yes, the color obtained from Alizarin after mordanting with Aluminium metal salts is also called Turkey Red. This is the red color popularly used in Dabu, Bagru, Tarapur, Kalamkari and Ajrak handblock prining of India. Alizarin is a mordant dye. Mordant is an additive which improves the ability of a dye to bond to the fabric. 

Mordant dyes are used in combination with salts of metal ions, typically aluminum, chromium, iron, and tin. The metal ions adhere to the fabric and serve as points of attachment for the dye molecules.So Aluminium present in Alum is used to generate that famous red color of alizarin. Other metal salts can be used as mordants for alizarin with some interesting color changes results. For example iron sulfate as the mordant imparts a rich brown color to the dyed fabric.

Alizarin, also spelled Alizarine, a red dye originally obtained from the root of the common madder plant, Rubia tinctorum, in which it occurs combined with the sugars xylose and glucose. The cultivation of madder and the use of its ground root for dyeing by the complicated Turkey red process were known in ancient India, Persia, and Egypt; the use spread to Asia Minor about the 10th century and was introduced into Europe in the 13th.

Laboratory methods of preparing alizarin from anthraquinone were discovered in 1868, and, upon commercial introduction of the synthetic dye in 1871, the natural product disappeared from the market for textile dyes.

There is a difference in Turkey Red and Turkey Red Oil. Turkey red oil, also called sulphonated (or sulfated) castor oil, is made by adding sulfuric acid to vegetable oils, most notably castor oil.It was the first synthetic detergent after ordinary soap. It is used in formulating lubricants, softeners, and dyeing assistants.

A trivia- Alizarin is something of a fungicide and pediculoside (that is why it found in the soldiers uniforms).

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Sources:

https://www.academia.edu/24482692/Natural_Dyeing_Fabric_dyeing_with_Madder

https://en.wikipedia.org/wiki/Alizarin

What is Space Dyeing and What are Space Dyed Fabrics

Space dyeing is a yarn dyeing technique in which a multicolor or blurred dye look is created. It creates a textured pattern and provides more color in the fabric.

Space dyeing can be done in any type of fiber- natural or synthetic. It is normally done on polyester, cotton, rayon, nylon and wool. 

In this method, the yarn is dyed at intervals along its length. There are two methods to produce. In the knit-de-knit method, the yarn is knitted first. Then the knitted cloth is dyed and then it is de-knitted. As dye cannot penetrate the areas where yarn cross, it creates alternate dyed and undyed spaces.

 In the other method, which is also a high speed method, the yarn must be wound on some dye package. It can be Dye Spring, plastic tube or steel tube. The chemicals are color mixtures are mixed and put in the individual color tanks of a space dyeing machine. Dyes are then injected using needles which are inserted into the package. 

https://www.cottonworks.com/wp-content/uploads/2018/01/Dyeing_Booklet.pdf

After dyeing the packages are placed in yarn conditioning machine for fixation and subsequently washed.

The below image gives the process steps

http://www.jogson.com/company_brochure.pdf

Multiple pattens can be produced as given below

http://www.jogson.com/company_brochure.pdf

Sources

1 2 3 4 5


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New Book on Dyeing- Why Turquoise Bleeds

Why Turquoise Bleeds?

Essential Dyeing Knowledge for the Merchandisers

A Book By

Priyank Goyal

Order Here

This book takes the reader through intricacies of understanding deing from a very beginner level. It covers all dye classes and their practical implications for the merchandiser.

Order Here

Product details Format: Kindle Edition File Size: 779 KB Print Length: 75 pages Simultaneous Device Usage: Unlimited Publisher: Priyank Goyal; 1 edition (6 October 2014) Sold by: Amazon Digital Services, Inc. Language: English ASIN: B00O8ZSVI6

Order Here There is a dearth of books in the market that can help merchandisers in understanding the basics of dyeing especially those who are not from the textile background. This book is an attempt towards fulfilling that gap. The author has tried as far as possible to keep the book away from the technical and chemical jargon and tried to present the material in the way that a layman who is introduced to this trade would understand.  This book can be taken as a complement to his other book for the merchandisers “Who is Mangalgiri? Essential Fabric Knowledge for the Merchandisers”, also published by Amazon. Apart from merchandisers, this book is suitable for students, teachers, traders, buyers, sellers and managers.  The first chapter “An introduction to Dyes and Classes of Dyes” clarifies the concepts related to dyeing. It introduces gently the readers to various dye classes such as direct, reactive, vat and others and their distinguishing properties.  The second chapter “A Few Details about dye classes” takes the reader through the details of the various dye classes such as the fibers they can be applied on, the method of application and the properties related to of those dye classes. It introduces in details the various terms related to the colorfastness of dyes.  The third chapter “Dyeing from Fiber to Garment Stage” takes the reader through the details of dyeing at various stages of textile chain, their advantages and the process of application.  The fourth chapter “Coloring by Pigments” introduces the concept of pigments, how they are different from dyes and their various methods of application.  The fifth chapter “Some practical notes for the merchandisers” takes the reader through the practical and commercial aspects of dyes, how to identify them in practical settings and other related issues.  The sixth chapter “Natural Dyes” introduces the concept of natural dyes, how these are different from the synthetic dyes. Their advantages and limitations and some commonly used natural dyes.  The seventh chapter “Dyeing with Indigo” takes the reader into details regarding indigo dyeing, the method and process of application and especially its use by the handloom weavers.  Order Here

Dyeing of Silk with Acid Dyes

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

Receipe

M:L- 1:30
Dye- X% on the weight of the material
Glauber Salt- 10% on the weight of the material.
Acetic Acid- 4-6% ( 40% strength)
Temperature: 85-90 deg C, pH-4-6, Time- 15 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 Glauber Salt
- Add dye solution.
- Enter the presoaked material at 40 deg C. Work for 10 minutes.
- Take out the material.
- Add acetic acid and stir well.
- Enter the material.
- Gradually raise the temperature to 85-90 deg C.
- Work for 35-40 minutes
- Take out the material followed by cold wash.
- Removal of excess water by using hydro extractor.
- Dyeing under shade.

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Manufacturing of Powerloom 40s x 40s 72 x 68 Fabric

This fabric is woven on the border areas of Andhra Pradesh and Tamil Nadu states of India and has a widepopularity as a dress material for ladies ( Kurtis and Salwars). It has the potential to be printed or embroidered.

The count for this fabric is 40s  both warp and weft and constructions is 72 and 68. It is available in both 44 inches and 56 inches.

The following are the broad steps in making the fabric

1. Yarn is taken in hank form and is kept in water tanks for two days for them to wet properly. Then the yarn is scoured in hank form itself.

Label on a Hank Yarn

2. Yarn dyeing is done using either reactive or vat dyes. Yarn dyeing is done manually.

Color Kitchen

Dyeing Bath for Hank Yarn - Reactive Dyes
  

3. Yarn is then subjected to sizing using Maida and Gum as components. The yarn is subjected to alternate dyeing and sizing three times.

Yarn Being Dried after Sizing

4. Yarn is then prepared for warping using an ingenious creel and then wound onto a weavers beam using a conventional sectional warping machines. 

5. Pirns are prepared using an indigenous contraption.

6. Yarn is then worked on powerloom having warp stop and weft stop motion.

6. Primitive dobbies are used for woven and zari borders.

 
7. The yarn is then subjected to finishing using water, sometimes in a padding mangle using softner and desizing agent.

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Factors influencing the cost of Processing

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

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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 Print Using Indian Natural Dyes

General Procedure

1. Tanning of Fabric with Myrabolan Powder

If myrobalan powder is taken

a. Take 200 gms of Myrobalan powder for 1 kg of fabric

b. Make a smooth paste with water, without any lumps

c. Add water till it becomes 5 liters.

d. Mix well

e. Soak the fabric in this

f. Work the fabric in this solution at room temperature for 15 to 20 minutes.

g. Squeeze the material and dry it in shade.

h. When dried, remove the unfixed material by striking it against wall.



2. Preparation of Thickening Agent

Using Tamarind Seed Powder

a. Add 100 gms of Tamarind seed powder in 1 liter of boiling wter.Sprinkle the powder in the boiling water stirring to avoid lumps.

b. Cook and mix till a fine paste is ready, cool it and filter the contents.

c. Remember that this paste is stable only for 2 to 3 days.

Or

Take Bhagvathi gum, add 30 to 50 gms of powder for 1 liter of water. It is also soluble in cold water.

This paste has better stability

Avoid Gum Arabic.

3. Mordanting the Solution with Mineral Salts

Take the mineral salts according to the following formula:

x parts of mineral salts
15 to 20% boiling water
70% thickening agent
to make it 100%.

The following are the general guidelines for getting the dark shades.

Alum= 10%, available by the name of Fitkari
Potassium Dichromate= 5%, available as Lal Kashish
Copper Sulphate= 10%, available by the name of mor Thuth
Ferrous Sulphate= 1 to 5%, available by the name of Hira Kashish
Iron Solution = 50%

Iron solution is made by the following procedure:

a. Take 2 kg of Iron Pieces, 1 to 1.5 kg of Jaggery and add 20 liters of water.

b. Keep in a plastic container for 3-4 weeks

Tin Chloride= 0.5 to 1.0 %

The Procedure for making the paste is:

a. Ground the mineral salt into powder form.
b. Add water and boil.
c. When completely dissolved, add the thickening agent.

The paste is ready for the printing process

4. Printing

Now Print the fabric using blocks. Dry and wash as follows:

5. Washing

 When washing in river keep the printed portion face down so that it touches water. Wash for about 5 to 10 minutes, printed portion is not touched. Care should be taken that printed portion should not touch the unprinted portion.

After washing, dry in flat on the ground. Dont hang. Now the fabric is ready for developing.


6. Developing of Color

Fabric is developed using traditional material. For yellow ranges Pomegranate rind ( Anar ka Chilka) or Forest Yellow (Amba Haldi) 50% or Moduga flowers ( Desuda phool) are taken. For Pinks to reds maroons Alizarin(0.5% with 10-20% Dhavdi flowers added to dye bath), Mnajistha(25-50%) is taken, for grey ranges: Rathanjoth(30% to 50%), Ferrous Sulphate is taken, for brown range: catechu ( Katha) and its componets are taken.

 Powder the dye and mix and boil with water for 3-4 boils. Filter it. Make a dye bath with material to Liquor ratio of 1:20 at 50 deg C. Add the solution in it. Enter the fabric ( already mordanted ) in it. Work well and raise the temperature to boil. Dye for 30-40 minutes. Wash and soap. Dry in shade.

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.

How to Perform Test for Color Fastness to Rubbing

Colour Fastness to Rubbing: Why Fabrics Sometimes Leave Colour on Other Surfaces

A common complaint in textiles is: “The fabric is giving colour.” Sometimes the colour comes out during washing, sometimes during perspiration, and sometimes simply by rubbing. A dark saree rubbing against a light blouse, a printed dupatta staining the neck area, denim leaving blue marks on a bag, or upholstery fabric staining clothing are all examples of poor colour fastness to rubbing.

The Indian Standard IS 766:1988 gives a method for determining the colour fastness of textile materials to rubbing. It applies to textile materials in different forms, including fabrics, yarns, textile floor coverings and pile fabrics. The test is carried out in two ways: dry rubbing and wet rubbing.

Visual 1: Colour fastness to rubbing test overview — fabric specimen, rubbing cloth, rubbing finger and stain assessment. AI generated- may have mistakes in details

What is colour fastness to rubbing?

Colour fastness to rubbing means the resistance of a dyed or printed textile to transfer its colour to another surface when rubbed.

In simple language, it answers one practical question:

If this fabric rubs against another fabric, skin, furniture, or garment part, will it stain it?

This is especially important in deep shades such as black, navy, maroon, red, indigo, bottle green and dark brown. It is also important in printed textiles, pigment prints, denim, sarees, dress materials, upholstery, carpets and pile fabrics.

Why rubbing fastness matters

A fabric may look attractive in the store, but if it stains another garment during use, the customer experiences it as a quality failure. Colour fastness depends not only on the nature and depth of the dye, but also on fibre type and the dyeing or printing method used. The same colouring matter may behave differently on different fibres or when applied by different processes.

For merchandisers, buyers and quality inspectors, this means one important thing:

Colour fastness cannot be assumed only from appearance. It has to be tested.

Principle of the rubbing fastness test

In this test, the textile specimen is rubbed with a standard white cotton rubbing cloth. After rubbing, the staining on the rubbing cloth is assessed using a grey scale for staining. Two tests are made: one using a dry rubbing cloth and another using a wet rubbing cloth.

The idea is very practical. If colour transfers to the white rubbing cloth, the fabric has lower rubbing fastness. If very little colour transfers, the fabric has better rubbing fastness.

Apparatus used

The test requires a rubbing testing device. For pile fabrics, including textile floor coverings, a larger rubbing finger is used: 3.2 cm diameter, with a downward force of 22 N, moving along a 10 cm track.

For all other textiles, a 1.6 cm diameter rubbing finger is used with a downward force of 9 N, again moving along a 10 cm track.

The rubbing cloth is a standard cotton cloth: desized, bleached, without finish, cut into 5 cm × 5 cm squares. A grey scale for evaluating staining is then used to rate the amount of colour transferred.

Visual 2: Dry rubbing and wet rubbing comparison — showing how the rubbing cloth is used in both test conditions. AI generated- May have mistakes in details.

Preparation of the specimen

For fabrics and textile floor coverings, the specimen should be at least 14 cm × 5 cm. Separate specimens are taken for dry rubbing and wet rubbing.

One specimen is taken with its long direction parallel to the warp, or direction of manufacture, and another parallel to the weft, or at right angles to the direction of manufacture.

This is important because rubbing behaviour may differ in warp and weft directions. In woven fabrics, yarn structure, surface hairiness, floats, finishing and print placement may not be identical in both directions.

For yarn or thread, it may be knitted or woven into fabric, or arranged as parallel strands on a cardboard rectangle to prepare the test specimen.

Dry rubbing test

In the dry rubbing test, a dry rubbing cloth is fixed over the rubbing finger of the testing device. The specimen is rubbed in a straight line along a 10 cm track, 10 times to and fro in 10 seconds.

The force applied depends on the type of textile being tested:

• 22 N for pile fabrics
• 9 N for other textiles

After rubbing, the cotton cloth is examined for staining. Loose dyed fibres pulled out during rubbing should not be mistaken for actual dye staining. The assessment should consider colouration due to staining by dyestuff.

Wet rubbing test

The wet rubbing test is similar, but the rubbing cloth is first wetted with water. The cloth should have about 100% water take-up. After rubbing, the cloth is dried at room temperature and then assessed for staining.

Wet rubbing is often more severe than dry rubbing. Many fabrics that pass dry rubbing may show lower performance in wet rubbing, especially dark shades, pigment prints, indigo-dyed fabrics and poorly after-treated dyed materials.

Multicoloured fabrics

When testing multicoloured textiles, the specimen should be positioned so that all colours in the design are rubbed during the test. If the colour areas are large enough, separate specimens may be taken and each colour assessed separately.

This point is very useful for printed sarees, dress materials, dupattas and furnishing fabrics. A single rubbing result may not represent the whole design if one colour is fast and another colour is weak.

Rating and reporting

The staining of the rubbing cotton cloth is assessed using the grey scale for staining. The report should give numerical ratings separately for dry staining and wet staining, and for each direction of manufacture.

Test condition	Direction	Rating
Dry rubbing	Warp direction	4–5
Dry rubbing	Weft direction	4
Wet rubbing	Warp direction	3
Wet rubbing	Weft direction	2–3

In general interpretation, a higher grey scale rating indicates less staining and better fastness, while a lower rating indicates more staining and poorer fastness.

Visual 3: Grey scale rating interpretation — higher rating means less staining and better rubbing fastness. AI generated- may have mistakes in details.

Special problem in pile fabrics

Pile fabrics can create a difficulty known as haloing, where heavier staining appears around the circumference of the stained area. The larger 3.2 cm rubbing finger can reduce haloing in many pile fabrics, although assessment may still be difficult for high-pile fabrics.

This is relevant for carpets, velvets, towels, blankets and certain upholstery fabrics. Their raised surface behaves differently from flat woven or knitted fabrics.

Practical meaning for textile buyers and merchandisers

For a buyer, rubbing fastness is not just a laboratory number. It has direct customer implications.

A dark saree with poor rubbing fastness can stain a blouse. A printed dupatta can stain the neck or kurta. A dark upholstery fabric can stain light garments. A poor pigment print can leave colour on hands. Denim with poor rubbing fastness can stain bags, shoes and car seats.

Therefore, rubbing fastness should be checked carefully in:

• Dark dyed fabrics
• Indigo and denim-like fabrics
• Pigment printed fabrics
• Sarees with strong contrast colours
• Upholstery and home textile fabrics
• Pile fabrics and carpets
• Fabrics expected to rub against skin or lighter garments

Common mistakes in understanding rubbing fastness

One mistake is to think that only washing fastness matters. A fabric may not bleed badly in washing but may still stain during rubbing.

Another mistake is to look only at dry rubbing. Wet rubbing is equally important because garments are often used in humid conditions, during perspiration, or after partial wetting.

A third mistake is to test only one part of a multicoloured fabric. In printed textiles, each colour may behave differently.

A fourth mistake is to ignore direction. Warp-way and weft-way rubbing results may differ, especially in fabrics with surface texture, floats or pile.

Knowledge nugget

Rubbing fastness is a surface-performance test. It tells us how well the colour is held on the textile surface when mechanical friction is applied.

This is why rubbing fastness is often a problem in dark shades, pigment prints and fabrics where dye fixation, washing-off or finishing has not been properly controlled.

Conclusion

The rubbing fastness test is one of the most practical colour fastness tests in textiles. It simulates a real-life action: one surface rubbing against another.

IS 766:1988 standardizes this test by defining the specimen size, rubbing cloth, rubbing force, rubbing distance, number of strokes, dry and wet conditions, and method of assessment.

For students, it teaches how laboratory testing connects to consumer use. For merchandisers and buyers, it gives a simple but powerful quality checkpoint. And for manufacturers, it reminds us that colour is not only about beauty — it is also about durability in actual use.

Suggested visuals to accompany this article

1. Colour Fastness to Rubbing Test Overview: A labelled diagram showing fabric specimen, white rubbing cloth, rubbing finger, rubbing direction and grey scale assessment.
2. Dry vs Wet Rubbing Fastness: A comparison visual showing dry rubbing cloth and wetted rubbing cloth, with examples of lighter and heavier staining.
3. Grey Scale Interpretation Chart: A simple educational chart explaining that rating 5 means no or negligible staining, while rating 1 means heavy staining.

Source

Based on IS 766:1988, Indian Standard method for determination of colour fastness of textile materials to rubbing.

General disclaimer

This article is written for educational and general understanding purposes only. The explanations simplify the testing method for students, merchandisers and textile professionals. For official testing, certification, dispute resolution, legal compliance or commercial acceptance, the original relevant Indian Standard and accredited laboratory procedures should be referred to.

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.

Trade Names of Natural Dyes

DYE SOURCE	BOTANICAL NAME/ SOURCE	TRADE NAME
Pomegranate	Punica granatium	Pacific
Myrobalan	Terminalia chebula	Kongo
Cutch	Acacia catechu	Thar
Kamala	Mallotus phillipinensis	Basant
Nut Galls	Quercus infectoria	Amber-M
Madder	Rubia cardifolia	Indus
Himalayan Rhubarb	Rheum emodi	Desert
Indigo	Indigofera tinctoria	Nile
Annato	Bixa orellana	Amazon
Lac	Coccus laccae	Rhine-M

You can find a tutorial on How to Use Natural Dyes here.  Receipes for natural dyes can be found here.

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.

FAQ in textile dyeing

Here is an amazing site to answer the following ( and many more) frequently asked questions on Dyeing:

Which dyes are more lightfast?

How can I fix non-reactive dyes

Is there anything I can do to "set" the dye on purchased fabric?

How can I dye spandex (or Lycra or elastane)?

How can I dye nylon?

How can I dye rayon?

How can I dye satin or charmeuse?

How can I dye polyester?

What are mordants? What's the difference between mordants and other dye chemicals?

What is soda ash? What's it used for?

What temperature should the soda ash be?

What is the effect of pH? What is the optimal pH?

What is urea for? Is it necessary?

What is the effect of temperature?

Should I use distilled or spring water instead of tap water?

Do I need to use salt?

How are thickeners such as alginate used with dye?

How do you use Silk Salt or other large salt crystals to make bursts of color?

Help! I ruined clothing by spattering bleach. How can I fix it?

How do you "bleach" a screen print on a t-shirt?

Can you tie dye something that is already dark?

How can I neutralize the damaging effects of chlorine bleach?

What chemicals can be used to remove dye?

Which Procion MX dyes discharge the best? Which are good at resisting chlorine bleach?

Which Procion MX dyes are pure, and which are mixtures?

Which MX dyes at one supplier are the same as those at another?

How can I mix Procion MX dyes to get specific colors?

What is in Procion type dye powder?

What other brand names are Procion MX type dyes sold under?

What do the letters and numbers in the code name for a Procion MX type dye mean?

Which Procion MX dyes discharge the best? Which are good at resisting chlorine bleach?

Which Procion H dyes are pure unmixed colors, and which mixtures? How do they compare from one retailer to another?

Which Wash Fast Acid dyes are pure, rather than mixtures?

What are Kiton Levelling Acid Dyes?

My colors just washed out! What happened?

My colors are not very bright. What did I do wrong?

Why are there specks of color all over my fabric?

Why did the thread stay white when I dyed clothing?

How do you tie-dye a star or mandela pattern?

How do you tie-dye a spiral?

How do you tie-dye letters of the alphabet?

How can I tie-dye a peace sign?

How can I dye clothing or fabric in the washing machine?

Can I paint on clothing with oil paints?

Can I screenprint with a dye resist?

How do you tie-dye socks?

Is it safe to eat or breathe fiber reactive dyes?

Which dyes are the safest? Which are the most dangerous?

Aren't natural dyes always safer than synthetic dyes?

Is all-purpose dye safer than fiber reactive dye?

Dyeing Hints

This site talks about very practical dyeing hints. Some of which are "animals are acidic and botanicals are basic", how to measure mordants and dyestuff, besides dyeing terminology.