Technical problems and solutions involved in garments Manufacturing

Garments Sewing Technical Problems & Solutions

Maruf Mahfuz

Cell no: 01738676060
Email: maruf.txt@gmail.com

Department of textile Engineering

World university of Bangladesh

Types of seam:

There may be hundreds of types of seams. but mainly 8 types of seams are used in garments making which are as follows:

1) Class-1: super imposed seam

2) Class-2: lapped seam

3) Class-3: bound seam

4) Class-4: flat seam

5) Class-5: decorative seam

6) Class-6: edge neating

7) Class-7: no descriptive name

8) Class-8: no descriptive name

1) Class-1(super imposed seam):

This is the most common garments. The simplest seam type within this class is formed by superimposing the edge of one piece of material on another. A Varity of stitch types can be used on this type of seam both for joining the fabric and for neating the edge or for achieving both simultaneously. Especially it is used in seam of shirt & trousers.

2) Class-2: (lapped seam):

This simplest type of seam of this class is formed by lapping two pieces of fabrics. The advantages & disadvantages of this type of seam are as follows

• Advantages:

1. As the selvedge of fabrics are best inward. The possibility of withdrawal of thread from the selvedge is low. Hence the strength and durability of seam is increased.
2. The possibility of seam slippage is very less

• Disadvantages:

1. Seam thickness is increased.
Use: For decorative effect on jacket and also used in jeans

3) Class-3(bound seam):

In this class, the seam consists of an edge of material which is bound by other. into the binding, the other material may be inserted for achieving an effect of design. Generally a contrasting colored fabric is used for edge binding. In figure (a) the simplest bound seam is shown which is not used in garments manufacturing. Because here fraying occurs in the fabric. The seam is shown in figure (b) is extensively used in garment in both functional and decorative purposes. For producing bound seam folding device is used in sewing machine. Bound seam is generally used in t-shirts, underwear, pants, sleeping suits etc.

4) Class-4 (flat seam):

This class of seam is called flat seam because the two fabric edges do not overlap. Sometimes, for decorative purpose a gap is kept between two edges and then seam is formed. Generally twin needle sewing machines are used for sewing flat seam. This class of seam is used in knitted garments and underwear as their thickness is less.

5) Class-5 (decorative seam):

Previously this class of seam was not regarded as seam and was given the name “stitching”. The main use of this seam is for decorative sewing on garments where one or more rows of stitches are sewn.

6) Class-6(Edge neating):

Seam types in this class include those where fabric edge are knitted by means of stitches. This is done for preventing fraying of threads of fabric from edges.the simplest type of edge neating is done by over lock machine. The using of folder may make the sewing easy. Various types of stitches can be for producing this class of seam.

7) Class-7:

Seams of these classes add separate items to the edge of a garment part. They are similar to the lapped seam except that the added component has a definite edge on both sides. This type of seam may be used to attach lace or elastic on the edge of fabric. Here a twin needle sewing machine with a folder is used

8) Class-8:

In this seam class only one piece of material is used to construct the seam. The most common seam type in this class is the belt loop as used in jeans, raincoats etc.

Stitch

• Every unit of a seam line formed by interloping, intralooping or interlacing of one or more threads is called stitch. 
• When one loop of a thread is passed through another loop of seam thread, it is called intralooping. 
• When one loop of a thread is passed through another loop of another thread, it is called interloping. 
• When one loop of a thread is passed over another loop of another thread, it is called interlacing.

Stitch Classes: 

About 70 classes of stitch are found to be used. Among them only 18-20 types of stitches are extensively used in garments industry. All these types stitch are grouped in following 6 classes.

1. Stitch Class- 100(Chain Stitch) 
2. Stitch Class-200 (Hand Stitch) 
3. Stitch Class-300(Lock Stitch) 
4. Stitch Class-400(Multi threaded chain stitch) 
5. Stitch Class-500(Over edge stitch) 
6. Stitch Class-600( Covering chain stitch)

(1) Stitch class-100(chain stitch):

Chain stitches are produced by one or more needle threads and are characterized by intralopping. One needle thread is passed through the fabric, from needle loop and secured by next loop formed by the same thread. Thus stitches are produced. This type of stitches i.e. chain stitch is very insecure. In case of breakage any stitch, it unravels very easily. The most common type of stitch of this stitch class-100 is type-101.as it is very insecure, it is generally used for temporary joining, positioning, button holing & button attaching.

(2) Stitch class-200(hand stitch):

The stitches of this class are originated as hand stitches. It produced from a single thread. This thread is passed through the fabric from one side to another and the stitch is secured by the single line of thread passing in and out of the material. Hand stitch is time consuming and costly operation which needs high skill for good appearance. Stitch type-209 is used at the edge of jackets. For producing this stitch special type of needle having eye at the middle and sewing machine is used. The hand stitch machine is hot so fast.

(3) Stitch class-300(lock stitch):

These types of stitches are produced with two or more groups of threads. Here the two threads are joined by interlacing. Loops of one groups are passed. Through the material and are by the thread of second group. One group is normally referred to as the needle thread and the other as bobbin thread. This stitch has enough strength and can be stretched up to 30%. It has the same appearance on both sides of the fabric which is not available in other stitches. Lock stitch are also much secured. They do not unravel in case of yarn breakage. The thread in a lock stitch generally beds well into the fabric which improves its abrasion resistance. The disadvantages of this class of stitch is, here the bobbin contains less amount of yarn than needle thread package. So the bobbin runs out during sewing. So the threading of bobbin is time consuming

(4) Stitch class-400 (multithread chain stitch):

This class of stitch is formed with two or more groups of thread. Loops of one group of thread are passed through the material and are secured by interlacing and interloping with loops of other groups. Here one group of thread is called needle thread and the other is called looper thread.

The most common and mostly used type of stitch of this class is stitch type – 401 which is produced by one needle thread and one looper thread.

(5) Stitch class-500(over lock stitch):

The stitch types in this class are formed with one or more groups of threads. Here at least one group of thread passes around the edge of material. So no thread from the fabric edge can come out. The most frequently used stitch of this type have one or two needle threads and one or two looper threads and thus forms a narrow band of stitching along the edge of the fabric. A trimming knife of the machine ensures a head prior to sewing.

(6) Stitch class-600(covering chain stitch):

These types of stitches are generally produced with 3 groups of threads. Threads of two groups can be seen from either side. The first group of thread is called needle thread, second group of thread is called top cover thread and the third group of thread is called bottom cover thread. The stitch of this class is very complex and up to 9 threads can be used.

This type of stitches is used in knitted garments, attaching laces, braids and elastic in garments.

Sewing problem:

Stitch, seam feed system; needle and thread together determines the seam appearance & performance. The problems which arise when material are sewn vary in their seriousness. Some are major problems which cannot be over locked and for these garments will be rejected by the inspector, where as someone minor problem which are negligible in low quality garments.

The sewing problems are as follows:

1. Problems of stitch formation.

(a) Slipped / skipped stitch

(b) Staggered stitch

(c) Unbalanced stitch

(d) Variable stitch density.

(e) Needles thread breakage.

(f) Frequent bobbin thread breakage

2. Problems of fabric distortion known as pucker or pucker problem.

(a) Seam pucker due to differential fabric stretch

(b) Dimensional instability of fabric

(c) Shrinkage of sewing thread

(d) Seam pucker due to fabric construction

(e) Seam pucker due to miss- matched patter

3. Problems of damage of fabric along the stitch line / fabric damage problem

(a) Mechanical damage

(b) Needle heating damage

1) Problems of stitch formation:

a) Slipped stitch:

If the continuation of stitches in a seam line is hampered by slipping some stitches it is called slipped or skipped stitch

Causes	Remedies
Hook or looper is not able to hold the needle loop.	Þ    Timing of hook or looper with needle should be appropriate. Þ    Replace the needle position correctly.
Loop size of needle thread is small.	Adjust needle & thread size.
Tension variation in looper & needle thread.	Adjust tension.

b) Staggered stitch

If the stitches produced by needle are not Parallel with the seam line they are called staggered stitch

Causes	Remedies
Needle deflection / vibration.	Þ    Needle size should be increased. Þ    Used tapper needle.
Faulty movement of feed dog.	Þ    Correct the feed dog motion.
Incorrect controlling of fabric into the feed mechanism.	Þ    Adjust the pressure of pressure foot. Þ    Change feed mechanism.
Due to lose fitting of needle butt inside the needle bar.	Þ    Assuring tight fitting of needle inside the needle bar

c) Unbalanced stitch:

Generally found in lock stitch. If the interlacement of the needle thread and bobbin thread does not take place at the middle of two layers of fabric unbalanced stitch is produced.

Causes	Remedies
Incorrect tension of sewing thread	Adjust thread tension
Incorrect passage of thread through the guide	Correct the passage of thread.

d) Variable stitch density: 

It is the variation of number of stitches per unit length of seam. The causes of variable stitch density and their remedies are mentioned below

Causes	Remedies
Insufficient pressure of pressure foot, causing uneven feeding of the fabric through the machine	Correct pressure
Materials of sticky or slippery surface	Increase pressure

e) Needle thread breakage:

Causes	Remedies
Improper unwinding of thread from package.	Place the package correctly so that unwinding can be performed easily.
Thread twisted in the guide.	Guide the thread correctly through the guide.
higher thread tension	Reduce tension in tension disc
Sharp edges of hook point, needle eye, bobbin case etc	Polish the sharp edges
Excess needle heating	Use higher quality needle / use lubricant
Lower quality of thread	Change thread

f) Frequent bobbin thread breakage:

Causes	Remedies
Faulty winding of thread in bobbin	Adjust bobbin winder correctly
Higher tension of bobbin thread	Reduce tension
Sharp edge of bobbin case	Polish the sharp edge
Improper fitting of bobbin case	Bobbin dimension should be checked
Bobbin or bobbin case may worn out	Change or repair bobbin

2) Problems of fabric distortion known as pucker or pucker problem:

Seam pucker is a major problem. Pucker is a wrinkled appearance along a seam when compared to a smooth fabric. 

Causes of seam pucker discussed below:

a) Seam pucker due to differential fabric stretch:

The prime requirement of feeding system is that it should move the plies of fabric past the needle and that all the plies should move together. But because of some reason if there is unequal stretch between the layers of fabric, then feeding of one layer becomes more than the other layer giving a rise to seam pucker.To remove feeding pucker the feed mechanism of the machine should be changed.

b) Dimensional instability of fabric:

When two or more than two layers of fabric are sewn and if one layer shrinks more than other after washing, seam pucker is seen. Hence before sewing two or more layers of fabrics, the potential shrinkage property should be considered.

c) Shrinkage of sewing thread:

If the sewing thread shrinkage, then seam pucker is occurred. This type of seam pucker is seen after washing on ironing. Before sewing the shrinkage potential of both the thread and fabric should be known. Synthetic threads have negligible wet shrinkage and should be used to remove the problem.

d) Seam pucker due to fabric construction:

In a compact fabric having high EPI & PPI, there is very little space left between the warp and weft yarns. While sewing such fabrics the threads are displaced around the needle and because of lack of space, pucker may be seen along the holes created by the needle. Such type of seam pucker is very difficult to remove but following steps may be taken:

• By using fine needle and fine thread.
• Reduction of stitch density.
• By changing the fabric it is possible.

e) Seam pucker due to miss-matched pattern:

If two pattern pieces of unequal length are joined, then one is joined with another by creating construction. This causes seam pucker. Mainly this type of problem is occurred due to designer fault.

3) Problems of damage of fabric along the stitch line / fabric damage problem:

The problem of fabric damage along the stitch line is mainly because of the use of unsuitable needle, sewing unsuitable fabrics or combination of both, there are two types of fabric damage because of needle

a) Mechanical damage.

b) Needle heating damage.

a) Mechanical damage:

Any damage of fiber on yarn of fabric by needle. 

To minimize the possibility precautions are:

• Needle size and point should be properly selected and needle should be free from damage or bending.
• Machine speed should be reduced.
• Application of lubricant which are spacing along the stitch line before sewing.
• Fabric sew ability test for specific or sensitive fabric should be done before sewing.

b) Needle heating damage:

Needle heating occurs as a result of friction between the needle & thread and between needle & fabric during sewing. The temperature may be 300°c to 350°c. At that temperature needle or fabric or both may be changed. In case of thread and fabric containing natural fiber has less possibility of damage. But synthetic fibers will melt at such high temperature. The damages are prevented by doing following apparatus:

• Speed: Slowing down the sewing speed to decrease the heat generation at the needle.
• Needle size and shape: By using finer needle, the temperature can be reduced.
• Cool air: By the flow of cool air through the needle, the temperature can be reduced to 70°c
• Lubrication: If lubrication is done along the seam line on thread and on needle the heat generation due to friction is reduced considerably.
• Sewing length: For long length sewing machine speed is required to drop & vice-versa.

Garments Manufacturing Process Sequence

Sequence of garments manufacturing

Maruf Mahfuz
Operations Officer
H.R Textile Mills Limited, Pride Group
Email: maruf.txt@gmail.com
Cell no: 01738676060

1. Design/ Sketch: 

 It in given by buyers to manufacturers containing sketches including measurement of all components.
2. Basic Block:  

Basic block is an individual component of garments without any design or style.

3. Working Pattern: 

The pattern set which is used for sample making is called working pattern.
4. Sample Making: 

 After getting all the specification the sample is mode and sent to the buyer for approval or to rectify the faults.
5. Basic Manufacturing Difficulties:  

The critical path is identified, that is the problems during production are simplified.
6. Approved Sample:  

After rectify the faults, sample is again sent to buyer, If it is OK then it is called approved sample.
7. Costing: 

 fabric consumption, making charge, Trimmings, Profit.
8. Production Pattern: 

 Add allowance with set dimension.
9. Grading:  

By following working pattern approved sample is made for medium size. It the buyer require different size. We have to grade the dimension. It may be S, L, M, XL, XXL, etc.
10. Marker Making: 

 Marker is a thin paper which contains all the components of all sizes of a particular style.
11. Fabric Spreading: 

 To spread the fabric on the cutting table properly for cutting.
12. Cutting:  

To cut fabric according to marker dimension.
13. Sorting & Bundling:  

Sorting out the component according to size & for each size make individual bundle.
14. Sewing: 

Sewing is done by different types of machine by the operator. Quality inspection is also done in that time.
15. Ironing & Finishing:  

Garments are treated by steam. Also several finishing process are done for example- extra loom thread cutting.
16. Final Inspection: Should meet specification given by buyers
17. Packing:   Poly packing
18. Cartoning:  

After packing the garments are placed in a hand paper box for export so as to minimize damage. The cartoons contain all the information over the box according to buyer’s instruction.
19. Sent to Buyers: 

 If everything is OK. It is sent to the Buyers.

Different Sections in a garments Industry

There are mainly four sections in a garments industry.

• Sample section
• Cutting section
• Sewing section
• Finishing Section

(1) Sample section: this section includes designing to marker making. The main function of this section is to make approved sample.
(2) Cutting section: This section includes process starting from “marker making to sorting & bundling” to cut fabric according to marker dimension is the main function of this section.
(3) Sewing section: This section includes only sewing. The function of this section is to make complete garments by using all of the cutting components for a particular style of garments.
(4) Finishing Section: This section includes process from “Ironing to sent to buyer’s, after making garments. It should treated by steam. Iron & use in it all of the finishing accessories & ultimately make the garments attractive as per buyer’s approved sample.

Some Definitions & Terms

Sample Garments:

Before going to star bulk production at first we have to make small quantity of garments which is sent to buyer for approval, these garments are called Sample garments.
Sample is always make upon medium size & it is quantity is at least 3-5 pieces or as per buyer’s requirements.

Approved Sample:

The sample which is approved by buyer is called approved sample.

Counter Sample:

 To run the production smoothly we made the some Extra sample. Which represents 100% same as approved sample this is called Counter Sample.

Product Package: 

Product Package is a sheet or no. of sheets which includes the following

• Design / Sketch
• Specification sheet or Measurement sheet
• Label Positioning
• Accessories required
• Stitch type

Pattern: 

Pattern is the replica of various separate components of a garment. These patterns are placed on fabric or on this paper (marker paper) to associate in fabric cutting.

Working Pattern:

The pattern which is made for sample making is called working pattern.
It is made for a particular style with net dimension working pattern is also called garments pattern.

Production pattern:

 production pattern is the patterns made for a particular style with net dimension along with allowance.

Marker: 

Marker is a thin paper which contains all necessary pattern pieces for all sizes for a particular style of garment in such a way that fabric wastage would be least.

Numbering: 

The process of identifying different fabric lay in a fabric lay out by numbering (1, 2, 3……..) them is called Numbering.

Numbering is two Type:

Lay Numbering: for maintaining shade.
Pieces Numbering: to assemble to Specific Size.

Sewing: 

Sewing is the most important step of garments manufacturing. Sewing is the way of joining of garments components with the help of needle and thread. It is the dominant process of garments assembling & still the best way of achieving both strength and flexibility in seam.

Objects of sewing: 

The objective of sewing is the construction of the seam of required standard and performance with an appropriate level of economy in production.

Seam:  

Seam is the join between two or more plies of material. Seams are usually formed by sewing but welding adhesive one often used for making seam.
In another way seam can be defined as seam is the application of a series of stitches on stitch type to one or several pitches of material.

Requirement of garments assembling/ sewing:

Cutting fabric components: 

All parts of a particular garment should at first be available before sewing.

Need same numbering cut pieces:  

At first all components of a particular lay of fabric should be given same number. For example, all the component of 3rd lay is given number 3 then the same numbered components are used for making a garment. That is number 3 pocket in joined with number 3 back part and with number 3 sleeves and so on. We should not joined a component of a lay with another component of different lay. This is maintained for avoiding shade variation in garment. Because the shade of fabric may differ from lay to lay and if such shade variation is occurred. The garment will be rejected.

DTM sewing thread:  

Dye to match (DTM) sewing thread is essential for sewing, because the colure of fabric and thread should be identical. Again the fastness of dye of both thread and fabric should be same. Otherwise are will be faded us before the other. After the sewing thread being available garment manufacturing is started.
All accessories must be available: For making garments several accessories are required. For example- Zipper, Button, Interlining etc are required. They should be available.

Proper needle selection: 

For sewing particular garment. Proper needle should be of proper size and point. For sewing knitted fabric the needle should be of ball point and for sewing woven fabric shaped V- pointed needle should be used.

Seam Performance:

Performance of seam means the achievement of perfect strength, elasticity, durability, security & comfort along with any special fabric properties like flammability & waterproofing. Performance of seam means achievement of following qualities..

• Seam strength
• Seam elasticity
• Seam durability
• Security of seam
• Comfort of seam

1) Seam strength:

Seam strength should be lower or equal to fabric strength. If seam strength is higher than the fabric strength then the fabric may tear due to unexpected force applied or the fabric seam strength depends on

• Strength of the thread used.
• Stitch density.
• Seam type.

2) Seam Elasticity: 

The seam should be equal or higher elastic then the fabric, otherwise when force will be applied fabric will be stretched more than the sewing thread & sewing thread may tear and seam may be opened. Seam elasticity varies depending on the types of fabric. That is knitted or woven.

3) Seam Durability:

Durability of seam should be equal or higher than the fabric, especially the seam should not be damaged or worm out due to friction and while cleaning.

4) Security of Seam:

While using the garments, the seam thread should not be torn or opened.

5) Comfortness of seam:

In close fitting or undergarments, seam must not present an uncomfortable ridge or roughness to the skin.

Seam Allowance:  

A predetermined amount of fabric between the edge of component parts of the garments and the seam line. Too small a seam allowance greatly reduces the seam strength. A seam allowance is measured from the cut-edge of fabric to the main line of stitches. Excessive seam allowance results in fabric wastage.

Garments Washing: Normal & Silicon wash

Comparative Study on Normal & Silicon Wash

Maruf Mahfuz 

Email: maruf.txt@gmail.com 

Department of textile Engineering

World university of Bangladesh

 Cell no: 01738676060

Introduction

The technology which is used to modify the appearance, outlook comfort ability and fashion of the garments is called garment washing.[1] Depending on garments construction different types of washing process can be done. Twill/Canvas/Knitted/Corduroy - Normal wash, Pigment wash, Caustic, Silicon wash Denim/Jeans/Gabardine - Enzyme wash, Stone wash, Bleach wash, Acid wash Grey fabric- Super white wash.[1]

Objective

Normal wash is required for the following reasons:

• The main aim is to remove starch dust and dirt from the garments.
• Sometimes softening and bringing a used look is also a reason of normal wash.
• For color garments removal of unfixed dyes can also be achieved to improve color fastness.
• In special cases intentional shrinkage in garments can be achieved.
• To remove dust, dirt, oil spot, impurities from the garments.
• To remove size materials from the garments.
• To remove starch presents on the garment fabrics.
• For soft feeling to wear the garments after purchasing.
• To achieve buyer washing standard.

Chemicals required for normal wash

• Detergent
• Desizing agent 
• Wetting auxiliaries
• Acetic acid
• Softener – Polyethelyne3
• Softeners – Silicone

Machineries used for Normal Wash

1. Washing machine

2. Chemical mixture machine

3. Hydro extractor machine

4. Dryer machine

Process flow chart of washing in industry:

Desizing

↓

Required washing

↓

Softening

↓

Hydro extraction

↓

Dryer

↓

Quality control

Process of Normal wash

The Normal/Garment washing process of batch of 70 kg Twill/Canvas Garments are described below:-

First Step:-

• Lot size: -....................... 70 kg Twill/Canvas Garment.
• Add water @ L: R = 1: 8-10 ............560 --700 Liter.
• Machine Running.
• Add detergent @ 0.5 gm. / liter ............ 280-350 gm.
• Temperature..... Sometime cold & sometime 40°c to 60°c.
• Time .............................. 5 to 10 mts.
• Drop the liquor.
• Cold wash.

Second Step:-

• Add water @ L: R = 1: 6 ......... 420 liter.
• Washing machine running
• Add Flax softener @ 0.6 gm. / liter .......... 252 gm.
• Add Acetic Acid @ 0.5 gm. / liter........... 210 gm.
• Time................................... 5 to 10 mts.
• Drop the liquor.
• Unload the Garments on trolley.

Third Step:-

• Hydro extractor machine.
• Hydrocxtraction the garment to remove excess water from the Garment.

Fourth Step:-Steam Dryer / Gas Dryer.

• Load on steam dryer -50 kg
• Temperature -60°c -70°c
• Time -40 -50 mts for dry.
• Time -10 -15 mts for cold dry.

or

• Load on gas dryer -50 kg,
• Running the machine
• Temperature: -70°c -85°c.
• Time: -30 -35 mts for dry.
• Time: -10 -15 mts for cold dry.

Fifth Step:-

After drying it will be quality checking and good quality Garments will be delivery to Garments factory and for further process.

Description

Garments can be inverted to minimize unwanted abrasion streaks (especially useful when preset creases are present). Load machine with garments. Desize with alpha amylase enzyme and detergent. Drain out the liquor. Rinse the substrate. Fill machine with water and heat to 60◦C.The liquor ratio can range from 10:1 to 20:1. A number of synthetic detergents can be used. Also, alkaline products such as soda ash or caustic soda can be added in amounts ranging from 0.5 to 2.0 grams/liter. Some chemical suppliers offer special products that accelerate the wash down process, dependent upon the particular dyestuff used. Wash/tumble action for 20-60 minutes, depending upon desired effect. Drain out the liquor and rinse. Apply softener. Tumble dry. Invert garments, if previously turned. Press, if required & then send it to the quality control section for checking.

Precaution

• Precautions are required to be taken for unwanted shrinkage issue and back staining
• Flax softener (cationic or nonionic) diluted with hot water then use in the machine[3].

After treatment:  

Softeners: [5]

The application of softeners at the end of the dye cycle improves the appearance, hand, and ease of pressing of the dyed garments after tumble drying. Durable press appearance ratings for 100% cotton woven garments after garment dyeing and tumble drying are usually around 1.0-1.5. The addition of a polyethylene softener in the final bath after dyeing generally increases this rating to 1.5-2.0. Use of a softener formulation with 2% polyethylene and 2% amino-functional silicone in the final rinse bath typically results in appearance ratings of 2.0-2.5, and ratings as high as 3.0 have been achieved for knit garments. As with all cationic softener systems, yellowing during drying may be a problem, and care must be taken to avoid unacceptable shade changes on white and pastel shades.

Figure: Atomic Structure of silicon

Treated with silicon softener

Silicone softeners have a firm place in final finishing for a very important reason. A piece of fabric which has been subjected to pretreatment ,dyeing and fixing processes is almost impossible to be appealing to any one without taking a corrective measures of handle[3]. 

Figure: General Structure of a silicone softener.

The Application of silicone softeners turns hard and a brittle fabric into a soft pleasant textile with which the buyer can expect a high degree of wearing comfort.
Silicone have wide spread applications in the textile industry from fiber, yarn and fabric production to final product finishing.Thier distinctive chemistry imparts a range of characteristics. A variety of silicon etechnologies  have application in the textile industry.

They include: 

•  Polydimethylsiloxanes.
•  Amido, Amino Functional Silicones.
•  Methyl Hydrogen Silicones.
•  Epoxy Functional Silicones.
•  Hydroxy functional Silicones.
•  Silicone Polyethers
•  Epoxy Polyether Silicones.

Figure: Working properties of silicon [4] 

Process:

The product, prediluted in a small quantity of water, is added to the rinse bath following the enzyme fading process at approximately 1.5-2.5 gms per liter (2.5-4% over weight of garments). Softener can also be used in the same bath as the enzyme fading process, depending on the level of back-staining desired. The product is to be added 30 minutes after the start of the enzyme fading process. The pre-diluted product is added in the same bath and treatment is continued for another 15-20 minutes. This does not inhibit the fading process and the processed denim garment has the same appearance and feel as that resultingbfrom the traditional pr cess In addition to its use in denim garment processing Softener can be used to process twill garments where a faded or washed look is typically achieved using cellulose enzymes. In this case Softener can be used in the rinse bath following the biopolish process or in the same bath as the enzyme bath. The twill garment will have a washed look and a soft hand.

Conclusion:

The purpose of washing laundry is to loosen dirt from the textile fibres and to rinse it off by using water as solvent. Depending on the laundry type and the degree of soiling, professional washing machines often provide a large number of different either adjustable or pre-defined washing programs. They vary e.g. in terms of using pre-washing, the number of rinsing cycles, the temperature or the program duration. All of the parameters should follow carefully to get fruitful result after washing shown by the garments, otherwise it will be difficult to the succeeding process like as softening finishing & ironing.

References

1. http://garmentec.blogspot.com

1. http://textilecollection.blogspot.com/2012/02/normal-washpigment-washcaustic-wash.html

3. http://seydel.com

4..http://www.google.com.bd/search?q=SILICONE+CHEMISTRY+FOR+FABRIC+CARE

5.www.dowcorning.com/ecosoftener

All About Garments Washing part- 5

Bleach Wash, Pigment wash and Caustic wash

Maruf Mahfuz

Email: maruf.txt@gmail.com 

Department of textile Engineering 

World university of Bangladesh

Cell no: 01738676060 

Bleach wash:

This in one an important step in washing denim & can be done by various bleaching agents
a. Calcium hypo chlorite
b. Sodium hypo chlorite
c. Hydrogen peroxide
d. Potassium permanganate

First two chemicals are commonly being used for every medium to vintage denim but when it comes to super vintage & light shade its advisable to use potassium permanganate bleach to cut the color faster till half way & then neutralize it & go with Liquid ( Hypo ) bleach to adjust the desired shade. This process helps to get Greyer cast & also protects the lycra/spandex , retain elasticity.

Hydrogen Peroxide is rarely used as bleaching agent when very less color loss required or if fabric is sulphur top. As it takes longer time to give desired effect.
Potassium Permanganate is also being used on 100% sulphur black denim fabric for bleaching/reducing agent to get unique effects. As its not production friendly till laundry have very expertise team to handle this program, otherwise it will result in many shades & cast.

Recipe for bleach wash:

Lot size 100 kg
M: L = 100 kg
Water = 1: 5
Hydrogen peroxide = 5 ml/ liter
Stabilizer = 1 ml/ liter
Caustic soda = 5 ml/ liter
PH = 10- 11
Temp. = 80 degree Celsius
Time = 60-70 minutes
After completion of bleaching part couple of hot wash is done,then it required neutralizing the garments with acetic acid
Acetic acid = 2 ml/ liter
Time = 5 minutes
Proper Neutralizations of bleaching process is very essential in order to get rid of fabric strength, bad smell from garment, yellowing & skin irritation etc.
In this process, a strong oxidative bleaching agent such as sodium hypochlorite or KMnO4 is added during the washing with or without stone addition. Discoloration is usually more apparent depending on the strength of the bleach liquor quantity, temperature and treatment time.

Limitations

* Process is difficult to control, i.e., difficult to reach the same level of bleaching in repeated runs.
* When desired level of bleaching reached the time span available to stop the bleaching is very narrow.
* Due to harshness of chemical, it may cause damage to cellulose resulting in severe strength losses and/or breaks or pinholes at the seam, pocket, etc.
* Harmful to human health and causes corrosion to stainless steel.
* Required antichlor treatment.
* Problem of yellowing is very frequent due to residual chlorine.
* Chlorinated organic substances occur as abundant products in bleaching, and pass into the effluent where they cause severe environmental pollution.

3-E bleaching concept for denim

Intensive research is underway for the development of sodium hypochlorite bleaching alternative eg, glucose bleaching, bleaching with sulphinic acid derivatives, and recently with laccase (enzyme).
Laccase enzyme belongs to the oxidoreductase group. Laccase’s oxidative effect is complex, and it does not work independently. A mediator is necessary and a chemical mediator is employed between enzyme and indigo.

Advantages

* New Laccase based bleaching technique only affects the indigo and natural raw white of weft yarn is retained, giving the woven fabric a darker shade, which is not implicitly achieved with hypochlorite bleaching.
* The product is so specialised on indigo that it does not attack any other dyes.
* Laccases open up the door to bleach Lycra containing denim without losing the strength of the fabric. In case of hypochlorite bleaching Lycra containing product affects adversely by losing the tear and tensile strength.
* Finally, the process is based on enzyme so no risk of environmental pollution and harmful effluent discharge.

Limitations
* Expensive, compared to traditional process.
* Heavy faded look is difficult to achieve. 

Enzymatic anti-backstaining agent-protease

The use of an engineered oxidatively stable alkaline protease that can tolerate a range of operating temperature and pH conditions offers flexible and alternative processes for backstaining clean-up, improved contrast of denim finishes, and reduced residual cellulase of fabric. It is claimed that significant reduction in back staining can be achieved at much lower temperature than conventional process by using small amount of protease either at the end of the cellulase washing step or during the rinsing step. By adding the protease at the end of the cellulase wash step, one rinse step is eliminated offering savings in time and energy. This process at lower temperature also claims to achieve a significant reduction of residual cellulase.

Bleach Wash procedure:
Bleach wash or light stone wash refers to light blue shades of denim. The additional step is bleaching to stone wash. This bleaching is usually carried out by strong oxidizing agents. In industry, most widely used chemicals are sodium hypo-chlorite, calcium hypo-chlorite, hydrogen per oxide and potassium permangate.

Bleach Wash Process of Garments:

A process of bleach wash of 60 kg batch of Denim Long Pant as mentioned below

First Step: Pre-treatment/ Desizing

Batch size.......................         60 kg Denim Long Pant.

Add water @ L: R = 1: 9....540 litres.

Start the machine.

Temperature....................   60°c

Add Desizing agent @        0.6 gm / litre ............ 324 gm.

Add Detergent /Antistain @1 gm / litre..... 540 gm.

Time................................     15 to 25 mts.

Drop the liquor.

Second Step: Hot Wash

Add water @ L: R = 1: 9..............      540 litres.

Temperature....................................... 60°c.

Time................................................. .. 5 mts.

Third Step: Bleaching

Add water @ L: R = 1: 8................................. 480 litres.

Machine running.

Add bleaching powder (k.c.i) @ 10 gm/litre.. 4800 Gms.

Add soda ash @ 5 gm/litre ............................... 2400 Gms.

Temperature............................................................ 60°c.

Time (Depend upon the shade).................... …12 to 15 mts.

Drop the liquor.

Rinse twice, each 3 minutes.

Fourth Step: Neutral Wash

Add water @ L: R = 1: 9.......................... 540 litres.

Add sodium hyposulphite @ 3 gm/litre ....... 1620 Gms.

Temperature ......................................................... 40°c.

Time (Depend upon the shade).............. 10 to 12 mts.

Drop the liquor.

Rinse one.

Fifth Step: Soft W

Add water @ L: R = 1: 8..................................480 litres.

Add Acetic Acid @ 0.6 gm/litre ..................... 288 Gms.

Cationic softner @ 1 gm/litre ........................ 480 Gms.

Time................................................................. 5 mts.

Drop the liquor.

Unload the garments to trolley.

Sixth Step: Hydroextractor Machine

Hydroextraction the garment to remove excess water from the washed garments.

Seventh Step: Drying Machine

Load 40 kg garments

Set temperature ................ 75°c to 85°c.

Time ......................... ……35 to 40 mts.

Time ..................... ………10 minutes in cold dry.

Eighth Step: Delivery 

After quality checking garment will be delivery.

Patch & Repairs along with Bleach Spots

These are totally manual processes to give uniqueness to Denim and to make it look VINTAGE. First cut or damage the units intestinally to desired area & then make hand repairs or machine repair to look natural. Diluted bleach can be used to spot the desired area followed by neutralization in wet process.  These process are time consuming hence productivity is low & reproducibility is very difficult but similar aesthetics can be achieved.  When we talk about Vintage denim, every garment should look unique & not a photocopy. These garments are sold at very high prices so customer should have a feeling of uniqueness & feeling different from others. Vintage denim is signature/ autograph of a brand & its image.

Fig: Different wash effect on denim fabric

 Tinting/pigment dyeing /pigment wash

Tinting is a process where very less amount of tint is involved & mainly direct dye is being used to do this process. This is being done to change hue/cast/tone of indigo. As soon as quantity of tint color increases & it cover up indigo, reaches the level of dyeing. Tinting being used to give garments a used / vintage & muddy look. This process takes from 5 minutes to 15 minutes time for better results followed by dye fixing & cleans up of superficial dye. Dyeing is being done on very light shade of Indigo, Ecru/ grey denim & Ready for dyeing denim.

• There are various Types Of Dye . The comparison of these dyes is given in the chart here below:

1-Direct Dyes

2-Reactive Dyes

3-Pigment Dyes

4-Sulphur Dyes

Direct Dyes	Reactive Dyes	Pigment Dyes	Sulphur Dyes
Economical	Costly	Cost Efficient	Economical
Wide range of shades	Wide range of shades	Styling ( limited to dull shades)	Shades are dull
Short Cycles	Long Cycle	Short to long Cycle	Short to long Cycle, depends upon shade
Ease of application	Water Consumption High	Machine contamination, but hard to obtain consistency, harsh hand feel	Sulphur Odour & harsh hand feel
Smooth Appearance	Smooth Appearance	Smooth Appearance	Smooth Appearance

 Table: Introducing different Dyes

Need to choose right color of pigment or tint with binder or fixer to apply locally on denim to get vintage look. This process also needs an artist to execute it nicely to merge the tint with ground indigo color & should not look too artificial. Pigments & Local tint also can be applied through spray gun or rubbing on desired area of denim garment. After application its must be cured in order to have permanent effect on jean.
As we can see from all the dry denim processes mentioned above, they are mainly manual processes. The quality of the worker can make or break the garment. Hence, great care has to be given to select the right personnel for these jobs

Caustic wash

Chemical usually used  caustic soda wash
Now, we will discuss on chemicals those are used in pigment washing.

Caustic Soda (NaoH) :
Caustic created the role in bleach technique without colour change the garments.
Caustic has a cleaning power which is more powerful then soda Ash.
Fadding affect/old looking affect come rapidly on garments.

Soda Ash (Na2Co3) :
Soda ash created alkaline medium for the breakdown of pigment dye.
It has also a cleaning power.
It has also help colour fadding affect of garments.

Detergent:
Here detergent is used to remove impurities from the Garment fabric surfaces and temperature helps detergent to enhance its action. Detergent removes the impurities from the garments fabric surface. During coming these impurities, some pigment will be washed out from the pigment dyed or printed area of the garments. As a result fadding affect will be developed.

Acidic Acid (CH3COOH) : 

Acidic Acid is used to neutralize the garment from alkaline condition and to control the pH value in wash bath.

Flax Softner (Cationic, Nonionic) :

Softener is used to make the garments treated textiles is surface feel that is bath sickly and soft and also provides excellent lubricating properties.

Process of Caustic Wash:

To be continued.............