How to Determine Fibre Composition in Blended Fabrics

Blended fabrics are very common in textiles. A fabric may contain polyester with cotton, cotton with viscose, acrylic with wool, elastane with cotton, or many other combinations. But when a fabric is made from more than one fibre, one important question arises:

How do we know the percentage of each fibre in the fabric?

This is important for quality control, costing, labelling, performance evaluation, buyer communication, export documentation and compliance.

Why Are Fibres Blended?

No single fibre gives all the desirable properties needed in a fabric. One fibre may give strength, another may give comfort, another may improve appearance, and another may reduce cost.

For example, polyester has very good strength, but it does not absorb much moisture. Because of this, 100% polyester fabric may not feel as comfortable as cotton. When polyester is blended with cotton, the fabric can get the strength of polyester and the comfort of cotton.

Fibre blending is generally done for three major reasons:

• To obtain different properties
• To suit changing fashion requirements
• To control the cost of the fabric

Once fibres are blended, it becomes necessary to determine the actual percentage of each fibre in the fabric. This is usually done by dissolving one fibre selectively and weighing the remaining fibre.

Visual 1: Why fibres are blended — strength, comfort, fashion and cost.

Basic Principle of Fibre Composition Testing

Most chemical methods for fibre composition work on a simple principle:

One fibre is dissolved in a specific chemical, while the other fibre remains undissolved.

The undissolved fibre is then:

• filtered,
• washed,
• neutralised if required,
• dried,
• cooled,
• weighed.

From the weight of the remaining fibre, the percentage of each fibre in the blend can be calculated.

1. Polyester and Cellulosic Fibre Blends

This method is used for blends such as:

• Polyester + cotton
• Polyester + viscose

A small sample of the blended fabric, usually 0.5 to 1.0 gram, is weighed accurately and placed in a flask. Then 75% w/w sulphuric acid is added. The material-to-liquid ratio is kept at about 1:200.

The flask is kept in a water bath at 50 ± 5°C for about one hour.

In this process, the cellulosic fibre dissolves, while the polyester remains undissolved.

The remaining polyester fibre is then:

• filtered,
• washed properly with water,
• neutralised with dilute ammonia solution,
• dried at 110°C,
• cooled,
• weighed.

The weight of the remaining fibre gives the percentage of polyester. The percentage of cotton or viscose can be calculated by subtracting the polyester percentage from 100.

Example:

If polyester remaining after the test is 65%, then:

Cellulosic fibre percentage = 100 − 65 = 35%

So the fabric composition is:

65% polyester and 35% cotton or viscose.

Visual 2: Selective dissolution principle — dissolve one fibre, weigh the remaining fibre.

2. Cotton and Viscose Blends

Cotton and viscose are both cellulosic fibres, so their separation is more delicate. The Bureau of Indian Standards has described four methods for determining cotton and viscose percentages:

1. 60% w/w sulphuric acid method
2. Sodium zincate method
3. Formic acid and zinc chloride method
4. Cadoxen solution method

Among these, the 60% w/w sulphuric acid method is commonly used.

60% w/w Sulphuric Acid Method

In this method, 0.5 to 1.0 gram of sample is weighed accurately and placed in 60% w/w sulphuric acid. The material-to-liquid ratio is kept at 1:100.

The solution is stirred properly by mechanical action for about 30 minutes.

In this process:

• Viscose dissolves
• Cotton remains undissolved

The cotton fibres are then filtered out and washed. After that, they are washed with water and treated with dilute ammonium hydroxide solution for neutralisation. Finally, they are dried and weighed.

However, in this method, the weight of cotton may also reduce by about 5%. Therefore, a correction factor is applied to calculate the actual cotton percentage accurately.

3. Polyester, Cotton and Viscose Blends

In a three-fibre blend containing polyester, cotton and viscose, separation is done step by step.

First, the sample is placed in 60% w/w sulphuric acid.

In this stage:

• Viscose dissolves first.
• Cotton and polyester remain.

The remaining fibres are washed, dried and weighed.

Then the remaining fibres are placed in 75% sulphuric acid.

In this stage:

• Cotton dissolves.
• Polyester remains.

The final remaining fibre is polyester. It is washed, dried and weighed.

In this way, the percentage of viscose, cotton and polyester can be determined separately.

4. Acrylic Blends with Wool, Silk, Cotton, Viscose, Polyester or Nylon

Acrylic fibre may be blended with many other fibres such as wool, silk, cotton, viscose, polyester or nylon.

In such blends, acrylic is first dissolved in dry dimethyl formamide, commonly known as DMF.

In this method:

• Acrylic dissolves in DMF.
• Other fibres remain undissolved.

The undissolved fibres are filtered, washed, dried and weighed. From this, the percentage of acrylic fibre in the blend can be calculated.

5. Protein Fibres with Cotton, Polyester, Nylon or Acrylic

Protein fibres include fibres such as wool and silk.

When protein fibres are blended with cotton, polyester, nylon or acrylic, they can be separated using alkali.

The accurately weighed sample is placed in a conical flask. Then 5% w/w sodium hydroxide or potassium hydroxide solution is added. The mixture is boiled for about 10 minutes.

In this process:

• Protein fibres dissolve.
• Other fibres remain undissolved.

The remaining fibres are filtered and washed thoroughly with water. Then they are washed with dilute acetic acid to neutralise the alkali.

Finally, the sample is dried, cooled and weighed. From this, the percentage of protein fibre and the other fibre can be calculated.

6. Polyester with Cotton or Viscose

Polyester can also be determined by using meta-cresol.

In this method, the blended fibres are weighed accurately and heated with meta-cresol.

In this process:

• Polyester dissolves.
• Cotton or viscose remains undissolved.

The remaining insoluble fibres are washed, dried and weighed. From this, the percentage of polyester is calculated.

7. Elastane, Spandex or Lycra with Cotton or Viscose

Elastane is also known by names such as spandex and Lycra.

When elastane is blended with cotton or viscose, it can be separated using DMF.

In this method, the mixed fibres are treated with DMF.

In this process:

• Elastane dissolves in DMF.
• Cotton or viscose remains undissolved.

The remaining fibres are filtered, washed, dried and weighed. From this, the percentage of elastane is calculated.

Visual 3: Fibre blend testing summary — fibre blend, chemical used and fibre dissolved.

Summary Table: Fibre Blend Testing Methods

Fibre Blend	Chemical Used	Fibre Dissolved	Fibre Remaining
Polyester + cotton/viscose	75% sulphuric acid	Cotton/viscose	Polyester
Cotton + viscose	60% sulphuric acid	Viscose	Cotton
Polyester + cotton + viscose	60% and 75% sulphuric acid	Viscose first, then cotton	Polyester
Acrylic + other fibres	DMF	Acrylic	Other fibres
Wool/silk + cotton/polyester/nylon/acrylic	Sodium hydroxide or potassium hydroxide	Wool/silk	Other fibres
Polyester + cotton/viscose	Meta-cresol	Polyester	Cotton/viscose
Elastane/spandex/Lycra + cotton/viscose	DMF	Elastane	Cotton/viscose

Why Fibre Composition Testing Matters

Fibre composition testing is very important in the textile industry because it helps in:

• correct fabric labelling,
• buyer compliance,
• export documentation,
• quality control,
• cost verification,
• performance evaluation,
• identifying wrong claims in fabric composition.

For example, if a fabric is sold as 80% cotton and 20% polyester, a laboratory can verify whether the actual fibre content matches the claim.

Similarly, in stretch fabrics, the elastane percentage may be small but very important. Even 2% to 5% elastane can change the stretch, recovery and comfort of the fabric.

Important Precautions

While carrying out fibre composition testing, the following precautions are important:

1. The sample should be weighed accurately.
2. The correct chemical concentration should be used.
3. The material-to-liquid ratio should be maintained.
4. Temperature and time should be controlled.
5. The residue should be washed completely.
6. Neutralisation should be done properly.
7. The sample should be dried and cooled before final weighing.
8. Correction factors should be applied wherever required.

Small errors in weighing, washing or drying can affect the final fibre percentage.

Conclusion

Fibre blending is done to improve fabric properties, reduce cost and meet fashion requirements. But once fibres are blended, it becomes necessary to know their exact proportion.

The basic method of fibre composition analysis is selective dissolution. One fibre is dissolved in a suitable chemical, while the other fibre remains. The remaining fibre is then washed, dried and weighed.

Different fibres require different chemicals. Polyester, cotton, viscose, acrylic, wool, silk and elastane all behave differently in different solvents. Therefore, correct identification of the fibre blend is necessary before selecting the test method.

For merchandisers, textile students, quality professionals and buyers, understanding these methods is very useful. It helps them read laboratory reports better and understand how fibre composition claims are verified scientifically.

General Disclaimer

This article is intended for educational and general textile knowledge purposes only. Actual fibre composition testing should be carried out only by trained laboratory personnel using recognised test standards, calibrated equipment, proper safety procedures and appropriate chemical handling protocols. Chemicals such as sulphuric acid, sodium hydroxide, potassium hydroxide, DMF and meta-cresol can be hazardous and should not be handled casually. Always refer to the relevant national or international testing standard before conducting any laboratory procedure.

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Silk Fabric Terms Explained — Part 4: Understanding the Crepe Family

In Part 1, we created a practical map for understanding silk fabric terms.

In Part 2, we discussed silk yarn terms such as raw silk, bivoltine silk, China silk, katan and organzine.

In Part 3, we understood twist-based sheer fabrics such as chiffon and georgette.

Now we come to one of the most important and most confusing families of fabrics:

The crepe family.

Crepe is not one fabric.

Crepe is a surface idea.

It refers to fabrics having a crinkled, puckered, grainy or pebbly surface. This effect may come from highly twisted yarns, special weave, chemical treatment, embossing or finishing.

This is why terms such as crepe, crepe fabric, crepe yarn, crepe-de-Chine, flat crepe and crepe-backed satin need to be understood together.

Central idea: Crepe is not only a fabric name. It is a fabric effect.

Crepe family map: yarn twist, weave, finishing and surface texture. Click image to view full size.

Why Crepe Is Confusing

Crepe becomes confusing because the word is used in many ways.

Sometimes crepe means the fabric surface.

Sometimes it means the yarn.

Sometimes it means a family of fabrics.

Sometimes it means a specific fabric, such as crepe-de-Chine.

For example:

Term	What It Refers To
Crepe	General crinkled or pebbly fabric effect
Crepe yarn	Highly twisted yarn used to create crepe effect
Crepe fabric	Fabric with crinkled, puckered or pebbly surface
Crepe-de-Chine	A specific lightweight silk crepe fabric
Flat crepe	A silk crepe with soft, almost imperceptible crinkle
Crepe-backed satin	A two-faced fabric: satin on one side, crepe on the other

So we should not ask only:

What is crepe?

We should ask:

Is the word crepe referring to yarn, surface, weave, finish or fabric type?

Once we ask this question, the family becomes much clearer.

1. Crepe

Crepe is a lightweight fabric made of silk, rayon, cotton, wool, man-made fibres or blends, characterized by a crinkled surface.

This crinkled surface can be produced in several ways:

• using crepe yarns,
• using high twist yarns,
• using special crepe weave,
• chemical treatment,
• embossing,
• or finishing.

Traditionally, crepe was mostly understood as a woven fabric. But crepe yarns are now also used to make knitted crepes.

Practical Understanding

Crepe is best understood by touching the fabric.

It does not feel completely smooth.

It may feel:

• crinkled,
• slightly rough,
• pebbly,
• springy,
• grainy,
• or softly puckered.

This surface gives the fabric a special appearance and handle.

Crepe fabrics often have better body than very smooth lightweight fabrics. They also hide minor wrinkles better because the surface is already textured.

Crepe in simple words: Crepe is a fabric with a deliberately crinkled, puckered or pebbly surface.

The word “deliberately” is important.

Crepe effect is not a defect. It is a planned fabric character.

2. Crepe Fabric

Crepe fabric is a fabric characterized by a crinkled, puckered or pebbly surface, usually made with highly twisted yarns in the weft and sometimes in the warp, or both.

A similar effect may also be obtained by using normal twisted yarn and crepe weave.

This definition tells us something very important:

Crepe effect may come from yarn or from weave.

That is why all crepe fabrics are not made in exactly the same way.

Crepe Effect from Yarn

When highly twisted yarns are used, the yarns try to contract or kink. During finishing, this creates unevenness and texture on the fabric surface.

This is the classic way of producing crepe effect.

Crepe Effect from Weave

Sometimes a crepe-like surface is produced by using a special crepe weave. In this case, the texture is not only due to highly twisted yarn but also due to interlacement pattern.

The weave scatters light and creates a broken, irregular appearance.

Practical Understanding

When you see a crepe fabric, ask:

Is the crepe effect coming from yarn twist, weave structure, finishing, or a combination?

This question is very useful for students, buyers and merchandisers.

Two fabrics may both be called crepe, but their construction may be very different.

3. Crepe Yarn

Crepe yarn is a highly twisted yarn, generally having about 1,200 TPM to 4,000 TPM, used for producing crepe effect in woven or knitted fabrics.

This is the foundation of many crepe fabrics.

A normal yarn lies relatively stable.

A highly twisted yarn stores energy.

When it is woven and later relaxed, the stored twist tries to express itself. This creates crinkle, grain and surface texture.

Practical Understanding

Crepe yarn is not a fabric. It is the yarn that helps create the crepe effect.

This distinction is important.

Term	Meaning
Crepe yarn	Highly twisted yarn
Crepe fabric	Fabric made with crepe effect
Crepe surface	Crinkled or pebbly appearance

Why High Twist Creates Crepe

When twist is inserted into yarn, the fibres or filaments are turned around the yarn axis.

At very high twist levels, the yarn becomes lively. It tries to twist back, curl or contract.

When such yarn is used in fabric, the yarn movement creates small irregularities on the fabric surface.

That is the beginning of the crepe effect.

Crepe yarn carries hidden energy. The fabric surface reveals that energy.

How crepe effect is produced: high twist yarn, crepe weave, chemical treatment and finishing. Click image to view full size.

4. Crepe/Georgette Yarn

Crepe/georgette yarn is a twisted yarn, usually with about 2,000 TPM to 3,600 TPM, generally made of two threads of raw silk.

This yarn is used for georgette and crepe-like fabrics.

We discussed this briefly in Part 3, but it is also relevant here because georgette belongs close to the crepe family.

Practical Understanding

Crepe/georgette yarn gives the fabric:

• grain,
• liveliness,
• drape,
• subtle crinkle,
• and a textured surface.

In georgette, this yarn is often arranged in S and Z twist directions to balance torque and create a uniform grainy surface.

So georgette can be understood as a sheer member of the crepe family.

5. Crepe-de-Chine Yarn

Crepe-de-Chine yarn, also called French yarn, is a hard twisted yarn, usually having about 1,600 TPM to 2,500 TPM. It is generally made from 3 to 5 raw silk threads.

It is used as weft in crepe-de-Chine.

This is a very specific yarn term.

The important points are:

• it is hard twisted,
• it is made from multiple raw silk threads,
• it is used mainly as weft,
• and it helps create the crepe-de-Chine fabric effect.

Practical Understanding

Crepe-de-Chine yarn is not the same as ordinary silk yarn.

Its twist level and multi-thread construction help create the soft crepe character of crepe-de-Chine fabric.

It does not usually produce a very harsh or rough crepe. Instead, it gives a refined and subtle crepe effect.

6. Crepe-de-Chine Fabric

Crepe-de-Chine fabric is a lightweight fabric made with highly twisted S and Z filament yarns alternating in the weft, and normally twisted filament yarn in the warp.

This definition is very important.

It tells us that crepe-de-Chine gets its character mainly from the weft yarn arrangement.

Breaking the Definition

Feature	Meaning
Lightweight fabric	It is not heavy or coarse
S and Z yarns	Yarns twisted in opposite directions
Alternating in weft	S and Z yarns are arranged alternately across the fabric
Normally twisted warp	Warp remains comparatively stable
Crepe effect	Comes mainly from high twist weft yarns

Why S and Z Twists Are Alternated

If only one direction of high twist is used, the fabric may become distorted.

By alternating S and Z twisted yarns, the twist forces are partly balanced.

This gives crepe-de-Chine a controlled crepe effect.

Practical Understanding

Crepe-de-Chine is usually smoother and softer than many rough crepes. It has a gentle crepe surface rather than a very strong crinkle.

It is suitable for:

• dresses,
• blouses,
• scarves,
• sarees,
• and flowing garments.

Crepe-de-Chine is a good example of controlled texture.

The fabric is not flat like plain silk, but it is not extremely rough either.

7. Flat Crepe

Flat crepe is a firm, mediumweight silk crepe with a soft, almost imperceptible crinkle.

It has crepe fillings alternating with two S and two Z twists. The surface is fairly flat.

Flat crepe may also be made of man-made fibres. It is used for dresses, negligees and blouses.

Practical Understanding

The name itself gives a clue:

Flat crepe is crepe, but with a flatter surface.

It does not have a very strong crinkled surface. The crepe effect is mild, controlled and subtle.

It gives a soft texture without making the surface too rough.

Why It Is Called Flat Crepe

In stronger crepes, the crinkling or grain may be clearly visible.

In flat crepe, the crinkle is almost imperceptible. The fabric surface remains fairly flat, but not completely plain.

So flat crepe can be understood as a refined crepe fabric with mild surface character.

8. Crepe-backed Satin

Crepe-backed satin is a two-faced fabric that can be used on either side.

One side is satin.

The reverse side, made of twisted yarns, is crepe.

This is a very interesting fabric because it combines two different surface characters in one cloth.

Practical Understanding

Satin side:

• smooth,
• lustrous,
• dressy,
• reflective.

Crepe side:

• textured,
• duller,
• grainy,
• less reflective.

This makes the fabric versatile.

A designer may use the satin side outside for shine, or the crepe side outside for a more matte and textured appearance.

Why Crepe-backed Satin Is Important

This fabric teaches us that fabric identity can be two-sided.

The same fabric can have two different faces because of yarn, weave and surface arrangement.

So when studying fabrics, we should examine both sides, not only the face side.

Crepe family comparison: crepe yarn, crepe-de-Chine, flat crepe and crepe-backed satin. Click image to view full size.

Crepe Family Comparison Table

Term	Type of Term	Main Character	Technical Basis
Crepe	General fabric family	Crinkled or pebbly surface	Yarn, weave or finish
Crepe fabric	Fabric type	Puckered or crinkled surface	High twist yarn and/or crepe weave
Crepe yarn	Yarn term	Highly twisted yarn	1,200–4,000 TPM
Crepe/georgette yarn	Yarn term	High twist silk yarn	2,000–3,600 TPM, often two raw silk threads
Crepe-de-Chine yarn	Yarn term	Hard twisted French yarn	1,600–2,500 TPM, 3–5 raw silk threads
Crepe-de-Chine fabric	Fabric type	Lightweight, soft crepe surface	S/Z high twist weft, normal warp
Flat crepe	Fabric type	Fairly flat, mild crinkle	Two S and two Z crepe fillings
Crepe-backed satin	Two-faced fabric	Satin face, crepe back	Satin weave plus twisted yarn reverse

Technical Note: Crepe Effect Can Be Produced in Four Ways

Crepe effect is not produced by only one method.

It can be created through:

1. High Twist Yarn

This is the most common method in silk crepes. Highly twisted yarn creates torque and surface crinkle.

2. Crepe Weave

A crepe weave uses an irregular interlacement arrangement to produce a broken, pebbly surface.

3. Chemical Treatment

Some crepe effects may be produced by chemical treatment, such as shrinkage effects.

4. Embossing or Finishing

A crepe-like surface can also be created mechanically through finishing.

This is why the buyer should ask how the crepe effect has been produced.

A true yarn-based crepe may behave differently from an embossed or finished crepe.

Practical Note for Buyers and Merchandisers

When buying crepe fabrics, do not rely only on the word “crepe”.

Ask the supplier:

Question	Why It Matters
Is the crepe effect yarn-based, weave-based or finish-based?	Explains durability of effect
What fibre is used?	Silk, rayon, polyester and blends behave differently
What is the twist level?	Helps identify true crepe yarn character
Is S/Z twist used?	Helps understand balance and surface texture
Is the crepe yarn in warp, weft or both?	Explains strength, texture and drape
Is it crepe-de-Chine, flat crepe or general crepe?	Helps identify exact product type
What is the fabric weight?	Affects fall, end use and transparency
Which side is intended as face?	Important in crepe-backed satin

The word “crepe” is only the beginning of the specification.

It is not the full specification.

Common Confusions

Confusion 1: Crepe Is One Fabric

No. Crepe is a family of fabrics and effects.

There are many types of crepe, including crepe-de-Chine, flat crepe, crepe georgette and crepe-backed satin.

Confusion 2: Crepe Yarn and Crepe Fabric Are the Same

They are not the same.

Crepe yarn is the highly twisted yarn.

Crepe fabric is the fabric showing crepe effect.

Confusion 3: All Crepe Effects Come Only from Yarn Twist

Not always.

Crepe effect can come from yarn twist, weave, chemical treatment, embossing or finishing.

Confusion 4: Crepe-de-Chine Is a Heavy Crepe

No. Crepe-de-Chine is generally lightweight and has a soft, refined crepe effect.

Confusion 5: Crepe-backed Satin Has Only One Usable Side

No. Crepe-backed satin is a two-faced fabric and may be used from either side.

Knowledge Nugget

Crepe is a wonderful example of how textile beauty can come from controlled irregularity.

A perfectly smooth yarn gives smoothness.

A highly twisted lively yarn gives movement.

A carefully balanced S and Z arrangement gives controlled texture.

A special weave gives broken reflection.

A finish can create surface character.

So crepe is not a defect.

It is planned disturbance.

It is controlled unevenness.

It is texture created by design.

Quick Recap

Term	One-line Meaning
Crepe	Fabric family with crinkled or pebbly surface
Crepe fabric	Fabric with crinkled, puckered or pebbly appearance
Crepe yarn	Highly twisted yarn used to create crepe effect
Crepe/georgette yarn	High twist yarn used for georgette and crepe-like fabrics
Crepe-de-Chine yarn	Hard twisted yarn used as weft in crepe-de-Chine
Crepe-de-Chine fabric	Lightweight fabric with alternating S and Z high twist weft
Flat crepe	Mediumweight crepe with mild, almost imperceptible crinkle
Crepe-backed satin	Two-faced fabric with satin face and crepe reverse

Reflection Questions

1. Why should crepe be understood as a family rather than one fabric?
2. What is the difference between crepe yarn and crepe fabric?
3. Why do S and Z twist yarns help in crepe-de-Chine?
4. How is flat crepe different from stronger crepe fabrics?
5. Why is crepe-backed satin considered a two-faced fabric?

Final Words

Crepe fabrics are beautiful because they are not flat.

They have life on the surface.

Their character comes from twist, weave, finishing and controlled irregularity.

Crepe yarn brings hidden energy into the fabric.

Crepe-de-Chine refines this energy into softness.

Flat crepe reduces the crinkle into a subtle surface.

Crepe-backed satin combines shine and texture in one fabric.

So the next time we touch a crepe fabric, we should not only say:

This fabric is crinkled.

We should ask:

What has created this crinkle?

That question takes us from market name to textile understanding.

And that is the real purpose of this silk terminology series.

General Disclaimer

This article is intended for general textile education and practical understanding. Textile terms, fabric names and trade usages may vary across regions, mills, suppliers and markets. The technical descriptions given here should be used as a learning guide and not as a substitute for laboratory testing, formal specifications, buyer-approved standards or supplier technical data sheets. For commercial buying, quality control or legal compliance, fabric composition, construction, twist, finish and performance should be verified through appropriate testing and documentation.

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Procion Reactive Dyes in Textile Printing -Part 3: Fixation Methods for Procion Printed Fabrics

Procion Reactive Dyes in Textile Printing

Part 3: Fixation Methods for Procion Printed Fabrics

In Part 1, we understood what Procion reactive dyes are, their types, and how printing paste is prepared. In Part 2, we discussed one-stage and two-stage printing processes, alkali timing, paste stability, resist salt, and discharge control.

Now we come to the final and most practical part:

How is the printed colour fixed on the fabric?

In textile printing, applying the colour on the fabric is only one part of the process. The real success of reactive dye printing depends on proper development or fixation.

If the dye is not properly fixed, the printed colour may look good initially but may wash out later.

What Is Fixation in Procion Dye Printing?

Fixation means making the dye react with the fibre so that it becomes permanently attached.

In the case of Procion reactive dyes, fixation happens when the dye reacts chemically with cellulose fibre under suitable conditions of:

• Alkali
• Moisture
• Heat
• Time

This is why printed fabric is not simply dried and finished. After printing, it has to be passed through a suitable development process.

In simple words:
Printing places the colour on the fabric. Fixation attaches the colour to the fibre.

Visual 1: Six fixation methods used for Procion printed fabrics.

Main Methods of Developing Procion Prints

After printing and drying, Procion printed fabrics may be developed by any one of the following methods:

1. Steaming
2. Baking
3. Flash ageing
4. Air-hanging
5. Vat development
6. Pad alkali–batch process

Each method has a different way of providing the required conditions for dye-fibre reaction.

1. Steaming Process

Steaming is one of the most important methods for developing Procion printed fabrics.

In this process, after printing, the fabric is first dried. It is then exposed to steam for a specific time. The steam provides moisture and heat, which help the reactive dye bond with the cellulose fibre.

Steaming Conditions

For fabrics printed with Procion-H and Procion-Supra dyes, the fabric is kept in steam for:

5 to 15 minutes

For fabrics printed with Procion-M dyes, the fabric is kept in steam for:

15 seconds

After steaming, the printed fabric is washed to remove unfixed dye and other chemicals. For viscose fabrics, moist steam is necessary.

Why Steaming Works

Reactive dye fixation needs moisture. Steam supplies moisture and heat together. This helps the dye move into the fibre and react with cellulose.

Steaming is especially useful for Procion-H dyes because they are less reactive and need proper fixation conditions.

2. Baking Process

Baking is another method used for developing Procion printed fabrics.

In baking, heat is supplied in dry form. Because moisture is less available compared to steaming, the recipe usually contains a higher amount of urea.

Urea helps retain moisture and supports dye fixation during heating.

Urea in Baking

When baking is used, the amount of urea is generally kept higher.

Usually, 200 parts of urea are added to 1000 parts of printing paste.

Alkali Used in Baking

For printing with Procion-H, the paste may contain:

15 parts anhydrous sodium carbonate per 1000 parts printing paste

For printing with Procion-M, the paste may contain:

15 parts sodium bicarbonate per 1000 parts printing paste

After printing, the fabric is dried and then baked under suitable conditions.

Baking Conditions for Procion Printed Fabrics

Dye Used	Cotton Temperature	Cotton Time	Viscose Temperature	Viscose Time
Procion-Supra	140°C	5 minutes	150°C	5 minutes
Procion-H	140°C	5 minutes	150°C	5 minutes
Procion-M	110°C	3 minutes	140°C	3 minutes

Visual 2: Steaming uses moist heat, while baking uses dry heat.

3. Flash Ageing Process

Flash ageing is a rapid development process. It is completed in two stages and is used for quickly fixing selected Procion dyes on cotton and viscose fabrics.

This process is based on the pad-steam method.

How Flash Ageing Works

1. The fabric is printed with a paste containing Procion dye and thickener, but without alkali.
2. The printed fabric is dried.
3. The fabric is padded with a cold alkaline solution containing salt.
4. Immediately after padding, the fabric is passed through a steamer.
5. The dye is rapidly fixed.

The key point is that alkali is not present in the original printing paste. It is applied later. This improves paste stability and printing quality.

Advantages of Flash Ageing

1. Since there is no alkali in the printing paste, printing quality is improved.
2. Fixation is completed in a very short time, about 40 seconds.
3. Printed fabric can be stored before development because alkali has not yet been applied.

Flash Ageing Printing Paste Recipe

Ingredient	Quantity
Urea	50 parts
Water	580–510 parts
Procion dye	10–80 parts
Sodium alginate	350 parts
Resist salt	10 parts
Total	1000 parts

In this recipe, urea is warmed with water. For Procion-H dye, it is heated up to about 90°C. For Procion-M dye, it is heated up to about 70°C. The dye is then added and dissolved with continuous stirring. After this, sodium alginate containing resist salt is added and mixed thoroughly.

Padding Solution for Flash Ageing

Ingredient	Quantity
Magnesium metasilicate	100 parts
Anhydrous sodium carbonate	150 parts
Anhydrous potassium carbonate	50 parts
Sodium chloride	100 parts
Water	500 parts
Gum	100 parts
Total	1000 parts

4. Air-Hanging Process

The air-hanging process is a simple method of developing Procion printed fabrics. It does not require large equipment, which makes it attractive in situations where steaming or baking facilities are not available.

However, it has one important limitation:

Procion-H dyes do not develop well by this method.

Air-Hanging Method

1. Pad the unprinted fabric with 2% soda ash and dry it.
2. Prepare Procion dye paste without adding alkali.
3. Print the soda-ash-treated fabric with this alkali-free paste.
4. Keep the printed fabric in air for several hours.

If the atmosphere is warm and humid, the results are better because reactive dye fixation needs moisture.

5. Vat Development

In vat development, the printing paste is prepared without alkali. After printing, the fabric is dried and then passed through a warm alkaline solution.

This method also follows the principle of keeping alkali separate from the printing paste.

Alkaline Solution for Vat Development

Ingredient	Quantity
Caustic soda, 38°Bé or 70°Tw	60 parts
Sodium carbonate, anhydrous	150 parts
Potassium carbonate, anhydrous	50 parts
Sodium chloride	100 parts

Water is added to make the total 1000 parts. This solution is warmed to 95–98°C.

6. Pad Alkali–Batch Process

The pad alkali–batch process is useful where steaming and baking facilities are not available.

In this method also, the fabric is printed with a paste that does not contain alkali. After printing, the fabric is padded with sodium silicate solution. Then the fabric is batched without drying.

Sodium Silicate Solution

Property	Value
Ratio by weight, SiO2 : Na2O	2.0
Specific gravity at 20°C	1.5
Viscosity at 20°C	200 centipoise

Batching Time

Dye Type	Batching Time
Procion-M	10 minutes
Procion-Supra or Procion-H	Up to 3 hours

To prevent the fabric from drying, it is covered properly with a polythene sheet. After batching, the fabric is washed thoroughly and dried.

Visual 3: Two-stage fixation routes where alkali is applied separately.

Comparison of Fixation Methods

Method	Main Principle	Alkali Position	Suitable Situation
Steaming	Moist heat fixation	Usually in paste	When steaming equipment is available
Baking	Dry heat fixation	Usually in paste	When baking equipment is used
Flash ageing	Alkali padding followed by rapid steaming	Applied after printing	Fast fixation and better paste stability
Air-hanging	Alkali on fabric, development in air	Applied before printing	Simple method, warm humid air helpful
Vat development	Warm alkaline treatment after printing	Applied after printing	Alkali-free paste and later development
Pad alkali–batch	Sodium silicate padding and batching	Applied after printing	Useful when steaming/baking is unavailable

Washing After Fixation

After fixation, washing is essential. The purpose of washing is to remove:

• Unfixed dye
• Thickener
• Alkali
• Salts
• Other auxiliaries

If washing is not done properly, the fabric may show poor washing fastness, staining, harsh handle, or shade dullness.

Important point:
In reactive dye printing, washing is not a minor finishing step. It is part of the quality of the final print.

Practical Notes for Textile Students

The six fixation methods may look different, but they all aim to achieve the same final result: the dye must react with cellulose fibre.

The difference lies in how each method provides alkali, moisture, heat and time.

• Steaming provides moist heat.
• Baking provides dry heat, supported by higher urea.
• Flash ageing applies alkali later and fixes quickly.
• Air-hanging uses alkali-treated fabric and atmospheric moisture.
• Vat development uses a hot alkaline bath.
• Pad alkali–batch uses sodium silicate padding and controlled batching.

Once this logic is understood, the methods become easier to remember.

Common Mistake

A common mistake is to think that once fabric is printed and dried, the process is complete.

It is not. In Procion reactive dye printing, drying only removes water. It does not necessarily fix the dye completely.

Fixation requires the correct combination of alkali, moisture, temperature and time.

Knowledge Nugget

All fixation methods are different ways of answering the same question:

How do we create the right conditions for the Procion dye to chemically bond with cellulose?

That is the heart of reactive dye printing.

Reflection Question

Why can pad alkali–batch processing be useful where steaming and baking facilities are not available?

Because the fabric can be printed without alkali, padded later with sodium silicate, batched under covered conditions, and then washed and dried after fixation.

Final Summary

Procion reactive dye printing is successful only when the dye is properly fixed on the fibre. The main fixation methods include steaming, baking, flash ageing, air-hanging, vat development and pad alkali–batch processing.

Each method has its own logic, equipment requirement and suitability. The printer must choose the method based on dye type, fabric type, available machinery, paste stability and production conditions.

For students, the most important understanding is this:
Printing gives the design, but fixation gives durability.

Without proper fixation, even a beautiful print may fail during washing.

Disclaimer and Safety Note: This article is intended for educational and informational purposes only. The recipes, chemical names, quantities, temperatures and process conditions mentioned here are provided to explain the principles of Procion reactive dye printing and should not be treated as direct instructions for unsupervised practical use. Textile printing involves the use of dyes, alkalis, salts, thickeners and other auxiliary chemicals, which should be handled only with proper knowledge, suitable safety precautions and appropriate supervision. Before using any chemical, always refer to the latest supplier technical data sheet, safety data sheet and applicable local regulations. Use appropriate personal protective equipment, ensure good ventilation, safe storage, careful measurement, spill control and responsible disposal of chemical residues and wastewater. The author and publisher do not accept responsibility for any loss, damage, injury or environmental harm arising from the direct or indirect use of the information given in this article, and readers are advised to consult trained textile processing professionals before attempting any laboratory or industrial application.

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Procion Reactive Dyes in Textile Printing - Part 2: One-Stage and Two-Stage Printing Processes Explained

Procion Reactive Dyes in Textile Printing

Part 2: One-Stage and Two-Stage Printing Processes Explained

In Part 1, we understood the basic nature of Procion reactive dyes, their classification, and the ingredients used in a typical printing paste. We saw that Procion dyes are suitable for cotton and viscose because they form a chemical bond with cellulose fibres under alkaline conditions.

Now we come to the next important question:

How is the printing process actually controlled?

In Procion dye printing, the key point is not only which dye is used, but also when alkali is introduced into the system. This gives rise to two broad methods of printing:

1. One-stage process
2. Two-stage process

Understanding this difference is very important because it affects paste stability, fixation, shade development, and print quality.

Visual 1: One-stage vs two-stage Procion dye printing process.

Why Alkali Timing Matters

In reactive dye printing, alkali plays a central role. It activates the reaction between the dye and the cellulose fibre.

But alkali also creates a practical problem.

Once alkali is mixed with the dye paste, the dye becomes more active. This means the dye may start reacting or losing strength even before it reaches the fabric. Therefore, the timing of alkali addition becomes very important.

A simple way to understand it:
Alkali is necessary for fixation, but if introduced too early, it can reduce paste stability.

This is why textile printers choose either a one-stage or two-stage process depending on the dye class, production requirement, and available equipment.

One-Stage Process

In the one-stage process, alkali is already present in the printing paste.

The fabric is printed with this complete paste, and then the printed fabric is fixed by a process such as:

• Steaming
• Baking

Since dye and alkali are present together in the same paste, the system is ready for reaction once the right moisture, temperature, and time are provided.

How the One-Stage Process Works

The general sequence is:

1. Prepare the printing paste with dye, thickener, urea, resist salt, water, and alkali.
2. Print the fabric.
3. Dry the printed fabric.
4. Fix the colour by steaming or baking.
5. Wash the fabric to remove unfixed dye and auxiliaries.

This method is convenient because the printing paste already contains the necessary ingredients for fixation.

Advantages of the One-Stage Process

The one-stage process is relatively simple to understand and operate.

Its advantages include:

• Fewer processing steps
• Alkali is already present in the paste
• Suitable for processes where immediate fixation is planned
• Convenient for steaming or baking-based fixation

However, the limitation is that the paste may not remain stable for long, especially when highly reactive dyes are used.

Limitation of the One-Stage Process

The biggest limitation is paste stability.

If the dye is highly reactive, the presence of alkali in the paste may make the paste unstable. This is especially important in the case of Procion-M dyes.

Procion-M dyes are highly reactive. Therefore, their paste should not be prepared too much in advance. It should be prepared only in the quantity needed for immediate printing.

Two-Stage Process

In the two-stage process, the printing paste is prepared without alkali.

The alkali is applied separately, either before or after printing.

This means the dye paste remains more stable because the chemical trigger, alkali, is not present in the paste at the beginning.

How the Two-Stage Process Works

There are two possible approaches.

1. Alkali Before Printing

The fabric may be treated with alkali first, dried, and then printed with dye paste that does not contain alkali.

This approach is seen in processes such as air-hanging, where the fabric may be padded with soda ash before printing.

2. Alkali After Printing

The fabric may first be printed with a paste that does not contain alkali. After printing and drying, the alkali is applied by padding or another suitable method.

This approach is used in processes such as:

• Flash ageing
• Vat development
• Pad alkali–batch process

Advantages of the Two-Stage Process

The two-stage process gives better control over the reaction.

Its advantages include:

• Better paste stability
• Cleaner printing in many cases
• Useful where the printed fabric has to be stored before development
• Better control over fixation
• Suitable for processes where alkali is applied separately

In this method, the dye and alkali are kept apart until the required stage. This prevents premature reaction and helps maintain paste quality.

One-Stage vs Two-Stage Process

Point	One-Stage Process	Two-Stage Process
Alkali position	Present in printing paste	Applied separately
Paste stability	Lower, especially with reactive dyes	Better
Process simplicity	Simpler	More controlled but involves an extra step
Fixation method	Usually steaming or baking	Alkali treatment before or after printing
Best suited for	Immediate fixation	Controlled fixation and better paste life

Visual 2: Why alkali timing controls paste stability and fixation.

Paste Stability of Different Procion Dyes

The stability of printing paste depends largely on the reactivity of the dye.

Procion-H and Procion-Supra

The paste of Procion-H and Procion-Supra dyes can remain usable for a long time, up to about 28 days.

This is because these dyes are not as highly reactive as Procion-M.

Procion-H is the least reactive among the three groups, so its paste stability is good. Procion-Supra has intermediate behaviour and also shows reasonable paste stability.

Procion-M

The paste of Procion-M does not remain stable for long.

Because Procion-M dyes are highly reactive, their paste should be prepared only as much as required.

This is a very practical production point.

If Procion-M paste is prepared in excess and stored for too long, the dye may lose its effectiveness and the final print may suffer.

Compatibility of Procion Dye Classes

Most Procion dyes can be used together to obtain different shades. However, compatibility depends on their reactivity.

Important practical rule:
Procion-H and Procion-M dyes should not normally be used together.

This is because Procion-H is slow-reacting, while Procion-M is highly reactive. Their fixation behaviour is different, and this may create difficulty in obtaining proper shade development.

However:
Procion-Supra and Procion-H can be used together.

This is because their behaviour is more compatible in practical printing conditions.

Role of Resist Salt in Procion Printing

During roller printing, it has been observed that colour may sometimes go to the back side of the fabric. This can affect the appearance and quality of the print.

To control this problem, resist salt is used.

Resist salt helps in preventing unwanted effects during printing and is especially useful where controlled print definition is required.

It is also used in discharge printing.

Resist Salt and Discharge Printing

In discharge printing, a reducing or discharge agent removes colour from selected areas of the fabric.

However, one practical problem may occur.

Sometimes the discharge effect does not remain limited only to the printed area. The surrounding area may also get affected. This can spoil the sharpness of the design.

To prevent this, the fabric may be treated before printing with a mild oxidizing agent.

Examples include:

• Sodium nitrobenzene sulphonate
• Sodium chlorate

These chemicals help neutralize the unwanted effect of reducing or discharge agents that may spread beyond the printed area.

Why Oxidizing Agents Are Used

If a discharge or reducing agent comes out from the printing paste and spreads to surrounding areas, it may unintentionally affect the fabric.

When the fabric has already been treated with a mild oxidizing agent, the reducing effect is reduced or neutralized.

In simple words:
The oxidizing agent protects the surrounding fabric from unwanted discharge.

This helps maintain cleaner print boundaries and reduces accidental damage to nearby areas.

Visual 3: Resist salt and oxidizing agent help control unwanted printing effects.

Foam Control in Printing Paste

Sometimes chemicals may also be added to the printing paste to prevent foam formation.

Foam can create problems during printing because it may lead to uneven application, spots, weak print areas, or poor design clarity.

Therefore, foam control is another small but important part of printing paste management.

Development After Printing

After the fabric is printed and dried, the colour has to be developed or fixed.

The main development methods include:

1. Steaming
2. Baking
3. Flash ageing
4. Air-hanging
5. Vat development
6. Pad alkali–batch process

These methods will be discussed in detail in Part 3.

Important point:
Printing applies the dye design, but development fixes the dye onto the fibre.

Without proper development, the dye may remain unfixed and may wash out.

Practical Understanding for Students

The difference between one-stage and two-stage printing is not merely a process detail. It is a way of controlling the chemistry of reactive dye printing.

In one-stage printing, the dye and alkali are together in the paste. This makes the process simpler, but paste stability can become a concern.

In two-stage printing, dye and alkali are kept separate until the desired stage. This improves control and paste stability but adds another process step.

The printer must balance:

• Dye reactivity
• Paste stability
• Print sharpness
• Fixation method
• Production timing
• Available machinery

This is why textile printing is both a chemical and practical craft.

Common Mistake

A common mistake is to think that alkali should always be added directly into the printing paste.

That is not always true.

In many processes, alkali is deliberately kept out of the paste and applied separately. This is done to improve paste stability, print quality, and process control.

Knowledge Nugget

In Procion dye printing, alkali is the trigger, but timing is the control.

Adding alkali at the right stage is one of the most important decisions in the printing process.

Reflection Question

Why does a two-stage process generally give better paste stability than a one-stage process?

The answer is simple:

Because the dye and alkali are kept separate until the desired stage of fixation.

Disclaimer and Safety Note: This article is intended for educational and informational purposes only. The recipes, chemical names, quantities, temperatures and process conditions mentioned here are provided to explain the principles of Procion reactive dye printing and should not be treated as direct instructions for unsupervised practical use. Textile printing involves the use of dyes, alkalis, salts, thickeners and other auxiliary chemicals, which should be handled only with proper knowledge, suitable safety precautions and appropriate supervision. Before using any chemical, always refer to the latest supplier technical data sheet, safety data sheet and applicable local regulations. Use appropriate personal protective equipment, ensure good ventilation, safe storage, careful measurement, spill control and responsible disposal of chemical residues and wastewater. The author and publisher do not accept responsibility for any loss, damage, injury or environmental harm arising from the direct or indirect use of the information given in this article, and readers are advised to consult trained textile processing professionals before attempting any laboratory or industrial application.

Buy my books at Amazon.com