List of Trimmings for a Shirt, Trouser and Jacket | Prepare a TrimmingList of Shirt, Trouser and Jacket

Experiment name: Prepare a trimming list of shirt, trouser and jacket.

Introduction:
The materials used in a garment except cloth to make a complete garment are called trimmings. Some trimmings can be seen from outside whether some are not. Again some trimmings are used for increasing beauty whether some for only function.

Objectives:
To list out the trimming names.

List of trimmings:
Now the trimming list for shirt, trouser and jacket is given below:

For shirt:

1. Button
2. Sewing thread
3. Interlinning
4. Linning
5. Label

For trouser:

1. Button
2. Sewing thread
3. Linning
4. Zipper
5. Label

For jacket:

1. Button
2. Sewing thread
3. Linning
4. Zipper
5. Label

Brief Description of Trimmings:

Button:
Buttons are the hardware items used in conjunction with button for the fastening of garments. The purpose of using buttons are-
Functional purpose.
Decorative purpose.

Types of button:

1) according to no of holes:
· 2-hole button.
· 4-hole button.
· Special button
– Shank button
– Snap button.
– Decorative button.

2) According to ligne no:
According to ligne no there are various types of buttons. Lange is the measuring unit of button diameter.

Zipper:
In making trousers, skirts and jackets chain or zipper is an essential component which is used to open or close the opening of garment.

Purpose of zipper:
i) Functional purpose of zipper is as a part of a garment.
ii) Where zipper is used as a decorative purpose it increases the beauty of garment.

Types of zipper:
Metal zipper.
Polyester or nylon coil zipper.
Plastic-molded zipper.

Label:
No garments can be sold without some kind of label attached to it. Specially in case of exporting, label on a garment is a must. Label is a attached compound of garment on which important information regarding the garment are written on printed.

There are mainly 3-types of label:
1) Main label.
2) Size label.
3) Care label.

Lining:
Linings are generally a functional part of a garment. They are used variously to maintain the shape of a garment, to improve the hang and comfort by allowing it to slide over other garment.

Linings are joined to main garment by sewing and for this normal sewing machines are enough. The method of attaching lining to outer garments depends on the garment type and on whether it is fully or partially bagged out.

Interlining:
Interlinings are used to support, reinforced control the shape of some areas of garments such as collars, cuffs, waist bands, facings and the front of coats. They are attached by fusing.

Conclusion:
The experiment gives us an idea about different types of trimmings. I would like to give special thanks to our teacher. I am also grateful to our instructors. I think this experiment will be very helpful in my future life.

Garments Pattern | Pattern Making | To Make a Pattern for Trouser

Experiment name: To make a pattern for trouser.

Objectives:

1. To know how to make a pattern for trouser.
2. To know about its importance.

Introduction: 

A pattern is the actual copy of different parts of a garment that is made by cutting board paper after sketching on it. According to this pattern cloth is cut and then garment is made. For industrial production different patterns are made for different size and a marker is made with these different patterns for a large-scale production. Then many cloths are cut at a time and finally garments are made by large number of workers in garments industry.

Pattern making

Functions: 

Now making a pattern has some functions. These are as follows:

1. To sketch the parts primarily according to the body on paper.
2. To make pattern for different size by increasing measurements.
3. To make a marker for large-scale production.
4. To use these patterns made by standard body measurement for many times.
5. Finally to save time and money to make fast and cheaper production.

Measurements for trouser: 

For making different sizes pattern our students are divided in 7 groups. I was in group 2. A pattern size for trouser is indicated by its waist size. Group 2 was given waist size 74 cm. Now for making a pattern of trouser other measurements are given below:

Parameter ……………..Measurement

• Waist ……………………………74 cm
• Seat ……………………………. 94 cm
• Body Rise ……………………..27.2 cm
• Inside leg ………………………79 cm
• Bottom width …………………24 cm
• Waistband depth …………….4 cm

Now the parameters are discussed below:

1. Waist: It is the joint place of the upper body and lower body of human.
2. Seat: There is a point at the bottom centre of a trouser that is called cross point. Now the seat is about 6-7 cm above this cross point.
3. Body Rise: Body Rise is the sum of front rise and back rise.
4. Inside leg: The measure along the sewn from the cross point to the bottom.
5. Bottom width: The diameter of the bottom of a trouser.
6. Waistband depth: it is the depth of waistband where the belt is we wear the belt.

Different parts of a trouser:  

A trouser has the following 6 parts:

1. Two sides of leg: Top side and bottom side (both has left and right part).
2. Waistband: Two pieces for left and right. Left piece is bigger because of having hooks.
3. Belt loops: According to the wish of pattern maker there may 5, 6 or 7 loops.
4. Fly piece: Two pieces for left and right.
5. Pocket back: There are total 4 pieces with 2 pieces for each left and right side.
6. Pocket facing: Two pieces for left and right side.

Apparatus:

1. Board paper – 2 pieces
2. Pencil 2B - 2 pieces
3. Eraser - 1 piece
4. Meter scale - 1 piece
5. Set square - 1 piece
6. Calculator
7. Scissor - 1 piece

Working Procedure: 

For the advantage of working the procedure is divided in 4 parts:

1. Top side
2. Under side
3. Pocket bag
4. Pocket facing
5. Fly piece
6. Waistband.

1. Top side
At first take a board paper and spread it on a flat table. Mark a point at the left top corner of board paper keeping space from top about 1 cm and from left 21 cm. Give this point number 0.

Now from 0 draw 3 lines at right angles to each other to the bottom, right and left sides. Then;

0-1 Body rise 27.2 cm + 1 cm. Spread the line both right and left side at right angle.
1-2 Inside leg 79 cm. Spread the line both right and left side at right angle to 1-2 line.
2-3 ½ of (1-2) + 5 cm. Spread the line both right and left side at right angle to1-2 line.
1-4 ¼ of body rise. Spread the line both right and left side at right angle to 0-1 line.
1-5 1/12 of seat + 1.5 cm. Draw a normal from 5 on 1-5 line that indicate 6 & 7 points.
6-8 ¼ of seat + 2 cm.
5-9 1/16 of seat + 0.5 cm.
7-10 1 cm. Draw front curve adding 9, 6 & 10 points.
10-11 ¼ of waistband + 2.5 cm.
2-12 ½ of bottom width.
2-13 ½ of bottom width. 

Then joint 12-14 & 13-15 with straight lines. During making curve 11-8 expanding 0.5 cm at outside and 8-14 compressing 0.5 cm at inside lines are drawn. During making curve 9-15 compressing 1 cm at inside lines are drawn.

2. Under side
Now on the same board paper this pattern is drawn. But the paper is rotated at 180º angles that the previous topside now becomes the bottom side and the bottom side into topside. Mark a point at the left top corner of board paper keeping space from top about 1 cm and from left 21 cm. Like the previous topside pattern 1-16 is drawn and then;

5-16 ¼ of 1-5. Draw a normal from 16 on 1-16 line that indicates 17 & 18 points.
19 Mid-point of 16-18.
18-20 2 cm.
20-21 1 cm.
9-22 ½ of 5-9 + 0.5 cm.
22-23 0.5 cm.
Then draw beck fork adding 23, 19 & 21 points.
21-24 ¼ of waist + 4.5 cm.
25 Mid-point of waist (21-24). Draw a 12 cm length line from 25 point at the bottom at right angle to 21-24 line and make 2.5 cm width dart.

17-26 ¼ of seat + 3 cm.
12-27 2 cm.
13-28 2 cm.
14-29 2 cm.
15-30 2 cm. 

Then draw side seam adding 24, 26, 29 & 27 points and draw inside leg adding 23, 30 & 28 points. Mark a point D at 12 cm distant from point 25. This is the mid-point of face for making back pocket. At mid distant of 12 cm indicate the width of pocket 14 cm. Now adding 5 cm hem allowance the topside and under side patterns are cut.

3. Pocket bag
On the topside pattern mark a point A at the point 28. Then;
A-B 5 cm.
B-C 19 cm.
B-F 17 cm.
F-E 32 cm.
E-D 17 cm.
Adding A, B, C, D, E & F points the pocket bag is drawn. Now the 2nd board paper is taken and this pocket bag is copied on this.

4. Pocket facing
A point B is marked at suitable place under or side of the pocket bag. Then;
B-C 19 cm + 2 cm.
C-D 6 cm.

5. Fly piece
Mark a point A under the pocket facing. Then;
A-B 24 cm.
A-C 5 cm.

6. Waistband
A point G is marked under the fly piece keeping available space. The waistband has two parts: Left part and right part.

Left part
G-H 4cm
G-I ½ of waist
I-J 4 cm
H-K 0.5 cm
Add G, I, J, H & K.
I-L 4 cm (fly piece extension)
Draw a normal on the expanded of HJ line.

Right part
The same drawing from G-K is drawn. Then;
I-M 9 cm (button stand extension)
Draw a normal on the expanded of HJ line.
Now after adding necessary allowance to the pattern pieces these are cut.

Precautions:

1. The table should be flat and smooth.
2. The pencil used should be soft and sharp.
3. The eraser should be clean.
4. During drawing the line should be drawn at a time.
5. No over drawing is allowable.
6. Measurement should be taken carefully.
7. To draw normal set square should be used.
8. The scissor should be sharp.
9. When cutting the seam should be cut at a time otherwise rough edge is produced.

Conclusion:
Skillness, technical knowledge, analytical power of drawing and special ability on technology of making garments are necessary for pattern making. Special care is very essential here because if any fault is occurred during making pattern such as design or measure or lack of any piece and if these faults are not corrected before marker making then the whole production is cancelled. So we should have clear idea and sufficient knowledge on pattern making and should be very careful during pattern making.

Interlining | Use of Fusible Interlining | Produce a Collar & Cuff of aBasic Shirt by Using Fusible Interlining

Experiment name: Produce a collar & cuff of a basic shirt by using fusible interlining.

Introduction:
Interlinings are used to support, reinforce and control areas of garments such as collars, hems, facings and the fronts of jackets and coats. They may be sewn into the garment or they may be attached by means of fusing.

Although fusing is now very common as a method of garment construction, there are many fabrics which are not suitable for fusing, as well as the small manufacturers who do not have the requisite equipment. The complexity of interlinings used varies greatly between tailored wear, especially menswear, and other types of garments.

Objectives:

1. To produce collar and cuff of a basic shirt.
2. To know how to use fusible interlining.
3. To know about how to sew the collar and cuff attached fusible interlining.

Working Procedure:
At first we made the pattern of collar and cuff. Then we cut the fabrics according to the pattern design. After cutting two pieces of fabric for collar was taken and similarly two pieces of fabric for cuff was taken.

Then, interning for collar was taken and placed on one part of the collar fabric. Then that interlining was joined by proper heat. After that, another part of collar fabric was joined with that interlining part and then by sewing we got a complete collar part for a basic shirt.

Similarly, we get a complete part for cuff of a basic shirt.

Lab Condition:
During this experiment we faced some minor problem, like unavailability of sewing machine. Moreover there occurred a huge gathering in interlining section, which killed a lot of time.

Conclusion:
Interlinings are available in a wide variety of weights and construction to match the properties of the garment fabrics they will support. They can be woven or non woven, both of which can be constructed to give a different softness or resilience in different directions. And our teacher helped us properly to get a proper knowledge about that interlining. And this knowledge may be very helpful in our future industrial life.

Different Types of Fabric -by Usage | Apparel Fabric | Beachwear Fabric| Blanket Fabric | Curtain Fabric | Drapery Fabric | Home FurnishingFabric | Hosiery Fabric | Industrial Fabric | Interlining Fabric |Mattress Fabric | Outdoor Fabric | Packing Fabric | Pin tuck Fabric |Quilting Fabric | Rugs & Carpets | Tapestry Fabric | Tent Fabric |Terry Fabric | Umbrella Fabric | Upholstery Fabric

Apparel Fabric

A woven fabric which is used in clothing and garments or for decoration and covering purposes. Use of these fabrics dates back to the 16th century when various fabrics like cotton, silk, wool etc. were used for making garments or apparels.

Beachwear Fabric  

Beach Wear fabric should be carefully chosen to give it a dignified yet comfortable feel. Nylon Lycra is the standard swim wear fabric that allows the beach wear to be stretchy yeast retains its shape and support. Neon prints and solids, Velvets are the other fabrics used for beach wear.

Blanket Fabric
This is a heavy, loosely woven fabric, usually of wool, used in bed clothing. Nothing lasts as long as wool and reversible fabrics backed with a Sherpa pile are as warm and soft as they are warm.

Curtain Fabric
Light weight and loosely woven fabrics are used in making curtains because these have the ability to control the amount of light to be let in. Some fibers like Cotton, Linen and Polyester hold up better under sun and are pretty safe fabrics for sewing curtains.

Drapery Fabric
Drapery fabric must suit the decor and have the right properties for the window’s treatment styling. Cotton, Linen, Acrylic Blends, Polyester Blends, Acetate, Nylon are the right choice of fabrics because of factors like strength, crease resistance, durability, wash-ability and reasonable price.

Home Furnishing Fabric
The textile fabrics are used to make bed spreads, blankets, quilts, curtain, table cloths etc. All home furnishing fabrics are of high quality such as Silk, 100% Cotton, Australian Merino Lamb’s Wool, Baby Camel Hair, Cashmere, Lama Alpaca, wool etc.

Hosiery Fabric
Hosiery are tailored coverings for the feet and its usage dates back to pre-history. Wool was once a primary material but nowadays cotton is much more common.

Industrial Fabric
Industrial fabrics are a strong and durable woven textile and are made from high performance, a made fibers such as fiberglass, carbon, and aramid fibers. Most of these fabrics are used in industries where high heat is present and high strength and dimensional stability are required.

Interlining Fabric
This fabric is used to provide warmth to any. Lycra, Sheer and Light weight Fabrics, Wool and Mohair Blends, Blends of Cashmere, Silk, Teflon treated Fabrics etc. are mostly used for interlining purpose.

Mattress Fabric
A comfortable mattress will help in a good night’s sleep and so the proper fabric should be used in the making of a mattress. For ex: Mattress protectors have an advanced polypropylene fabric with a luxuriously soft texture. Thus these mattresses are more comfortable to sleep in.

Outdoor Fabric
Available in a vast variety, outdoor fabrics possess thermal, fire and abrasion resistant properties. Made from natural as well as man-made fibers, these fabrics are further manufactured into casual and sportswear.

Packing Fabric
Packing fabric is widely used to protect goods and materials while in transportation from one place to another. Generally made of stretch material, these fabrics retain their shape for long time to come.

Pin tuck Fabric
Pin tuck fabrics are used to beautify or decorate the garments. They are mostly used for women blouses and other clothing.

Quilting Fabric
Quilting is used for padding a fabric; this two layered fabric is easy and comfortable. Cotton, silk and wool blends, polyester are popular options.

Rugs & Carpets
The fabric used to manufacture rugs and carpets are made of both natural as well as synthetic fibers, they can not only be easily cleaned but also easily moved.

Tapestry Fabric
One of the oldest forms of woven fabric, tapestry fabric is available in multi colors and multi patterns to enchant the onlooker.

Tent Fabric
Tent fabric is generally made from strong and durable material to weather all conditions. Natural fabrics are blended with synthetic ones for making it stronger.

Terry Fabric
Made of cotton, terry has a lot of absorbing capacity; it is extensively used to make towels, bathrobes and bath gowns.

Umbrella Fabric
Beautiful and useful umbrella fabric is made of canvas, linen, duping, as they are durable and strong. It also protects from the harmful UV rays.

Upholstery Fabric
Upholstery fabrics are woven into beautiful and eye caching patterns and designs. They are not only tough and durable but also do not soil or fade; easy to maintain. 

Seam | Uses of Seam | Production of Different Types of Seam

Experiment name: Production of different types of seam.

Objects:
01) To know about various classes of seams.
02) To produce the seams on fabric by sewing machines.
03) To know the formation & construction process of various seams.

Different Types of seam :
01) Class-1-Super imposed seam
02) Class-2-Lapped seam
03)Class-3-Bound seam
04) Class-4-Flat seam
05)Class-5-Decorative seam
06)Class-6-Edge Neatening(Over Lock)

01) Super imposed seam:
The seam of class-1 is called superimposed seam. This is the most common & mostly used seam for joining fabrics. In this seam, two plies of fabric are placed on one another perfectly & then the fabrics are sewn. The sewn edges of the fabrics remain in the same side.

Uses:
In side seams of shirts, trouser, children wear etc. Piped & French seam are used for decorative purposes.

02)Class-2- Lapped seam:
The seam of class-2 is called lapped seam. At least two plies of fabric is required to produce this type of seam. The two Sewn edges remain in two opposite sides of the sewing line/seam line.

Uses:
This class of seam is not mostly used for sewing garments. This seam is used in sewing jeans pants, lunges etc.

03)Class-3- Bound seam: The seam of class-3 is called bound seam. For producing bound seam at least two plies of fabric are required. The edge of One ply of fabric is bounded by the other. Folder is used in sewing machine for producing bound seam.

Uses:
Used in sewing men’s underwear, Guernsey, pants, sleeping suits etc.

04)Class-4- Flat seam:
The seam of class -4 is called flat seam where zigzag stitches are used by 2-needle sewing machine. In this seam two plies of fabric are placed side by side & then they are sewn together by zigzag stitching.

Uses:
This seam is widely used in under garments & in knitted items.

05)Class-5-Decorative Seam:
The seam of class-5 is called decorative seam. This seam is used in order to decorative purpose. The fabric which we used that would be folded in several times and then according to the under side of the folded part of the fabric stitch can be produced.

Uses:
Cartains,Table clotchs,Furniture wears,Decorative ladies wears et

06)Class-6-Edge Neatening:
The seam of class-6- is called edge neatening which is used to holds the edge of the fabric such that the yarns of the fabric can not open easily.All the over Lock stitch is edge neatening class seam.

Uses:
To protect the fabric edge such that the warp yarn of the fabric can not easily open.

Conclusion:
This experiment is very helpful to us. By this experiment we can learn about various types of seams. This experiment will be helpful for our future practical life. So we should be done this experiment very carefully & sincerely.

Stitches | Garments Stitches | Production of Different Types of Stitches

Experiment name: Production of different types of stitches.

Introduction:
Seam and stitch are related to each other. Because stitch can not be made without seam and vice versa. Seam is the join between two or more plies of pieces of material. Seams are usually formed by sewing. Sewing is done by joining one or more threads or loops of threads with intralooping, interlooping or interlacing. Stitch is the unit of this sewing.

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

Objectives:
1) To identify different types of stitches.
2) To observe the formation and structure of stitches.
3) To know about the uses of various types of stitches.

Theory:
About 70 types of stitches are found using and from these types 18 to 20 types of stitches are mostly used in garments industries. All types of stitches are classified into 6 classes. They are

1. Stitch class-100 : Chain stitch
2. Stitch class-200 : Hand stitch
3. Stitch class-300 : Lock stitch
4. Stitch class-400 : Multi thread chain stitch
5. Stitch class-500 : Over edge/Edge neatening chain stitch
6. Stitch class-600 : Covering chain stitch

Now they are described below:

Stitch class-100: Chain stitch:
Chain stitches are produced by one or more needle threads and are charcterised by intralooping. One needle thread is passed through the fabric, form needle loop and is secured by the next loop formed by the same thread. Thus stitches are produced. This type of stitches is much unsecured. In case of the break of any stitch, it unravels very easily. The most common type of stitch is stitch calss-100 is stitch type-101. As it is very unsecured it is used for biasting operations which are temporary stitching operation for the positioning of collar, cuff and flaps etc.

Stitch class-200: Hand stitch:
This type is originated from hand stitches. It is 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 garment. Hand stitching is a time consuming and costly operation which needs high skill for good appearance. Stitch type- 209 is used at the edges of jackets. For producing this stitch a special type of needle having at the middle and sewing machine is used. Normally this type of stitch is used in costly dresses.
 

Stitch class-300: Lock stitch:
This type of stitches is produced with two or more groups of threads. Here the two threads are joined by interlacing. Loops of one group are passed through the material and are secured by the thread of second group. On e group is referred as needle thread and other as bobbin thread. This stitch has enough strength and same appearance on both sides. Lock stitches are also very secured and don’t unravels in case of yarn breakage. The disadvantage is bobbin contains less thread and so runs out during sewing. As a result the bobbin is again threaded after sometimes which time consuming and disgusting. Lock stitch is extensively used for joining fabrics collar, cuff, pocket, facing etc. Top stitching is used for button holing, attaching, blind stitching etc.

Stitch class-400: Multi thread chain stitch:
This class is formed with two or more groups of threads. Loops of one group of thread are passed through the material and are secured by interlacing and interloping with loops of another group. Here on group is called needle thread and another group looper thread. The most common is stitch type-401 which is produced by one needle thread and one looper thread. It has an appearance of lock stitch on the top but has a double chain effect formed by a looper thread on the under side. Sometimes stitches in this class are called ‘double lock stitch’ because the needle thread is interconnected with two loops of the under thread. Here the possibility of seam pucker is very less. Again all threads are supplied from cone packages so there is no possibility of running out thread. This type of stitches is used foe sewing lace, braid and elastic. Stitch type-401 is used in jeans and trouser.

Stitch class-500: Over edge/Edge neatening chain stitch:
The stitch type in this class is 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 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 neat edge prior to sewing. Stitch type-504 is formed of a needle thread and two looper threads. This class of stitch is used for edge neatening and for producing seam in knitted fabric. The extensibility of this stitch is very good. The width of this stitch is 3-5 mm. This stitch type can be used to make a decorative neated edge.

Stitch class-600: Covering chain stitch:
This type of stitches is 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 is called top cover thread and the third is called bottom cover thread. The stitches of this class are very complex and up to 9 threads can be used in producing these stitches. For producing stitch type-606, 4 needle threads and 5 other threads are required and it is called flat lock. Flat lock stitches are used in knitted fabrics especially in under wears. It is also used in decorating leisure wears. Stitch type-602 is used for attaching laces, braids and elastics in garments. Moreover it is used in decorative stitches and top stitching.

Conclusion:
The experiment gives us an idea about different types of thread and their parameters that will help me to choose a good thread. I would like to give special thanks to our teacher. I am also grateful to our instructors. I think this experiment will be very helpful in my future life.

Sequestering Agents | Functions of Sequestering Agents in Dyeing |Characteristics of Sequestering Agents

Introduction:
Sequestering agent is a dyeing auxiliaries which is used during dyeing for removing hardness of water.Sequestering agents combine with calcium and magnesium ions and other heavy metal ions in hard water. They form molecules in which the ions are held so securely (sequestered) that they can no longer react.

Sequestering agent

The most undesirable impurities in Fibre, Common salt, Glauber salt, Caustic Soda and Soda ash are the di- and tri-valent cations, e.g., Ca++, Mg ++ Cu ++, Fe+++ etc. These ions increase hardness of the process bath and generate iron oxides in the bath. Calcium and Magnesium reacts with alkali and precipitates as a sticky substance on the textile material, which creates patchy dyeing and discoloration of the fibre. The ferric oxide with cellulose and creates small pinhole on the fibres also damages the machinery by scale formation in the nozzles and base.

To overcome these deleterious effects in the scouring and bleaching bath adequate amount of sequestrant must be used. Sequestrants prevent di-and tri-valent metal ions, e.g., Cu++, Fe +++ , Mn ++, Ca++, Mg++ etc from interfering with the chemical processing of the textile material. It prevents catalytic damage of cellulosic fibres in bleaching hath during hydrogen peroxide bleaching.

Thus, unwanted metal salts cause a lot of problems in processing. Now, with the focus on minimising costs and maximising efficiency, consistency and fastness are two important parameters that every dyer would like to achieve first time. This reduces reprocessing costs, making him competitive.

The dyer has to use a suitable sequestering agent in the process, wherever it is required. Selection of the right sequestering agent is very important. First and foremost, the sequestering agent should chelate offending metal ions under the given condition and should form a stable complex, which does not decompose over a prolonged processing period.

Now a days many other types of sequestering agents are widely used in textile processing. The three main stages in which sequestering agents are used are

1. Pretreatment
2. Bleaching
3. Dyeing

There are some main type of commercial sequestering agents are:

1. Aminocarboxylic acid base products
2. Phosphates and Phosphonates
3. Hydroxy carbroxylates
4. Polyacrylates
5. Sugar acrylates

1. Aminolycarboxylates
In aminopolycarboxylates, it is assumed that one molecule of sequestering agent complexes with one ion of metal. Depending upon the pH of the medium, i e acidic, neutral or alkaline, the preferential sequestering order or each product could change.

Some of the characteristics of some of these sequestering agents are summarised as below:

EDTA: Good sequestering agent for calcium and magnesium at alkaline pH but no sequestering agents on Fe3+ at alkaline pH. Not stable with oxidising agents. Low solubility in acidic medium.

NTA: Sequestering of Fe3+ only at acidic pH but sequestering of Cu2+ between pH 3 to 12. Low solubility in acidic medium. Not stable with oxidising agents.

DTPA: Good sequestering action Fe3+ under alkaline pH but complexes with alkaline earth salts are less stable than EDTA. slightly more resistant to oxidising agents. Low solubility in acidic medium.

2. Phosphates and Phosphonates
These sequestering agents are divided in two broad classes:

• Inorganic polyphosphates such as sodium hexameta phosphate (SHMP), sodium polyphosphate, sodium tripolyphosphate, sodium trimeta phosphate, sodium pyrophosphates
• Phosphonated aminopolycarboxylates such as EDTMP, DETMP, ATMP, HEDP, DTPMP

Inorganic phosphates work under specific conditions and work as sequestering agents by converting troublesome metal ions into water soluble complex by a process of ion exchange.

Phosphates of aminopolycarboxylic acids or phosphonates are derivatives of phosphorous acid and are characterised by a C-P bond, which has stronger hydrolytic stability than the P-O-P bond of polyphosphates. This type of sequestering agent has emerged as a major class of sequestering agent, since these possess more features than mere chelation. These characteristics are: Threshold effect, i e inhibition of precipitation of CaCO3, CaSo4 with sub-stiochiometric quantities of inhibitor

1. Corrosion inhibition
2. Resistance to hydrolysis
3. Deflocculation i.e. stability effect on colloidal suspensions

Compared to popular amino polycarhoxylic acid based sequestering agents, these phosphonates based sequestering agents have a high chelation ratio. Apart from better chelation value or better chelation ratio, these phosphonates also have better iron chelation than EDTA and NTA.

3. Hydroxy Carboxylic Acids
Organic compounds that have several hydroxylic groups often have the property of preventing precipitation of bi and trivalent metal cationis in an alkaline medium. Some of the well known products in this category are:

Citric acid, Tartaric acid, Gluconic acid and Oxalic acid.

These are less important sequestering agents, compared to aminocarboxylic acid or phosphonates. Gluconic acid/sodium gluconate has been found to be an effective chelating agent for iron under alkaline conditions.

4. Polyacrylates
Polyacrylates are effective dispersants, with mild chelation values and protective colloid properties. The chelation values of polyacrylates have no demetallising effect on metal containing dyestuffs. They are completely non foaming.

They are very suitable as dyebath conditioners, soaping agents and washing aids. Being non surface active agents they are easily rinsable and thus reduce the quantity of water required for removing their traces from the substrates, unlike all surfactants. The typical chelation values offered by polyacrylates do not come close to the chelation values offered by amino polycarboxylates or the phosphonates. This problem has been overcome by development of sugar acrylates.

5. Sugar Acrylates
Sugar acrylates have sequestering values as high as amino polycarboxylates or the phosphonates. They are biodegradable, effective components in cellulosic fabric pretreatment during desizing, scouring, bleaching and mercerising. These products are characteristed by good chelation values from the acidic to the alkaline range and from temperatures of 45 to 115øC. They also exhibit no demetalising effect on metal-containing dyestuffs and are non-foaming. They are ideally recommended in pretreatment for desizing, scouring and bleaching and as dyebath conditioners during the cellulosic dyeing.

Factors to be taken into consideration while selecting a sequestering agent for the process :

1. Stability Constant: 

As chelation is a reversible reaction, the equilibrium is dependent on the process pH and the concentration of the metal ions and chelating agent, which react together to form a chelate. The stability of the metal complex is expressed in terms of its stability constant. If we represent chelation of metal ion, Mm+ with sequestering agent, An- as: Mm+ + An- MA(m-n) then the stability constant is Ks = MA (m-n) (Mm+) (An-)

A high value of Ks indicates high sequestering effect. For example, in the case of aminopolycarboxylates, the stability constant for same metal iron increases in the order NTA, EDTA, DTPA.

In the case of metal ions, the stability constant increases in the order.

From the above information it can be deduced that the NTA-Mg2+ complex has the least stability, whereas DTPA - Fe3+ has the highest stability. Thus, in a process, if more than one metal ion is present, the metal ion having the highest stability will be chelated preferentially. If chelating agent is present in sufficient quantity, the metal with the highest stability constant will be chelated completely, followed by the next metal ion in te order given above. Even after chelation is complete in this order, if additional metal impurity, with metal having a higher stability constant, is introduced, then this metal ion will displace low stability constant metal ions from the complex. For example, Fe3+ displaces Ca2+ from a Ca2+ chelating agent complex. Of course, the chelating agent should be capable of chelating Fe3+ under given conditions.

2. The pH of the Process: 

The pH of the system will influence the formation of the chelation complex. For example, NTA, EDTA cannot chelate Fe3+ under alkaline conditions, whereas DTPA can. HEDP can chelate Fe3+ up to pH 12, and so also gluconic acid.

3. Demetalisation:  

This property is particularly important for dyeing and printing with premetallised dyes - for example, some direct, reactive and premetallised metal complex dyes. If Ni2+, Cu2+, Cr3+, Co2+ or Fe3+ is present in premetallised dyes, these could be preferentially chelated ahead of Ca2+ and Mg2+, due to the higher stability constant of these metal ions. Therefore pretrials in the lab are required to establish the suitability of the chelating agent, and also to arrive at the optimum concentration for the given process, when premetallised dyes are to be used.

4. Other Features:  

Stability of chelate to prolonged process periods, dispersing properties, crystal-growth inhibition, effect on equipment, etc. are also to be considered when selecting a commercial sequestering agent.