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Concepts of Knit Garments Merchandising

M.R. Karthikeyan, 
Expatriate Lecturer in Textile Engineering,
Kombolcha Institute of Technology, 
Wollo University, Ethiopia
Email : srimrk@yahoo.com

Merchandising denotes all the planned activities to execute and dispatch the merchandise on time taking into consideration the 4 R’s of expediting Right Cost, Right Quantity, Right Quality and Right Time.

Functions of Merchandisers:
  1. Execution of Sample orders
  2. Costing.
  3. Programming.
  4. Yarn Procurement Arrangements.
  5. Production Scheduling (or) Route CARD Drafting.
  6. Accessories arrangement (order placing follow-ups).
  7. Approval of various processors’s sewing operations and finishing processes.
  8. Pattern approval (or) Dummy size set approval.
  9. Size set approval.
  10. Preproduction sample follow-ups.
  11. Pilot run inspection.
  12. In process inspection.
  13. Production controlling.
  14. Identifying shortages and make arrangements for the shortages.
  15. Shortage quantity and quality following quality control procedures.
  16. Following quality assurance procedures.
  17. Maintaining the junior’s activities of in house and sub-contractor units.
  18. Buyer communication.
  19. Communication with production units, processing units and other third party’s (vendors).
  20. Proper reporting.
  21. Highlighting to the management.
  22. Record maintenance (Records pertaining to merchandising).
  23. Developing samples.
  24. Placement of orders.
  25. Taking measures for consistent production.
  26. Taking preventive actions to maintain the targeted Performance level in all areas of merchandising.
  27. Attending meetings with superiors and furnishing the required details about merchandising.
1. Sample order execution:
After the receipt of the Specification, pertaining to the sample order, the merchandiser has to
understand what the requirements of buyers are. Sometimes there may be amendments related to any of the specifications in the sample order sheet. It is the duty of the merchandiser to execute sample order and dispatch on time the “Right quality.”
Knit garment
2. Costing:
The merchandisers should know the following details while costing.
  • Yarn cost.
  • Process cost (Knitting, Bleaching, and Raising etc.)
  • Rates pertaining to various sewing operations.
  • CMT(Cut Make Trim) Rate.
  • Ironing charges, packing charges and accessories rate.
  • Overheads.
  • Shortage (or) wastage 3%.
  • Free on Board (FOB) (Transport charges) 2% to 3%.
  • Insurance 2%-3%,
  • Buyers’ agents commission 5%-6%,
  • Quota rate per garment.
  • Profit 15% - 20%
3. Programming:
Most probably programming is done by production manager. In some companies it is done by the
merchandisers. The following factors should be considered in programming.

1. Allowances:
  • Fabric structure
  • Dia. fixation (knitting dia., calendaring dia. and compacting dia.)
  • Process loss (shrinkage etc.)
  • Size wise piece weight
  • Extra quantity required
  • Size wise requirement (dia., colour (or) combination)
4. Route card Drafting (or) Production Scheduling:
For each and every order Route card (or) Production scheduling is to be done by the merchandisers. It facilitates the merchandiser to follow up the orders in planned manner. The following details (or) aspects should be considered in drafting (or) scheduling.
  • Design
  • No. of sewing operations
  • No.of processes
  • Despatch date
  • No. of Components
  • Type of stitches
  • Order quantity
  • Production capacity of the in houses (or) sub-contractors unit and processing units.
  • Prioritizing the other factors
  • Targeted dates for various processes (or) stages of merchandising.
  • Actual finishing date (To cross check the deviation between the planning and actual performance any stage (or) Process). Targeted dates for all the stages of merchandising should be decided. Actual dates on which a particular process (or) operation is actually done should also be entered in production scheduling. The merchandisers are accountable for the deviation.
5. Accessories arrangements:
Merchandiser has to make arrangements for the timely delivery of the required accessories to the
concerned units. Accessories requisition slip may be used for requirement purpose. The merchandiser has to cross check the actual requirements after verifying the details furnished in accessories requisition form. After the receipt of accessories quality check will be done.

6. Approvals:
Approval is an authentication of all required conformances related to a process (or) an operation. The merchandisers should know the quality parameters of various processes and sewing operations before approvals. There should not heron-conformities. Evidences for approval should be cross checked to confirm that all the approvals having made properly.

7. Approval of various processes sewing operations and finishing processes:
The various process of sewing operations and finishing process such as patter making, cutting,
sewing, ironing will be approved by the technical merchandisers

8. Pattern approvals:
Patterns should be approved for
  • Measurement
  • Style and fit
  • Allowances
  • Accuracy of pattern
If there is any non-conformance in pattern that should be corrected before it is used in production
Pattern approval samples will be received from the concerned units and approved by the approval
department (or) merchandisers, If there is non-conformance in any size sample revised sample for that size should be again submitted for approval.

9. Size set approvals:
Size set approvals are made by the approval department or) by the merchandisers. All the quality
parameters related to various processes, sewing operations have to be cross checked. The below
mentioned aspects should be considered.
  • Measurements
  • Aesthetics
  • Process quality
  • GSM
  • Piece shrinkage
  • Washing fastness of the piece
  • Sewing operation quality
  • Print (or) embroidery position
  • Labeling instructions.
  • Size set approval seat will be prepared in triplicate.
  • Washing fastness of garment should be verified.
  • Shrinkage in garment can also be verified.
10. Pre-production samples:
This samples should he submitted on time to the concerned person (Buyers, buyer agents office
buying office). All the quality parameters have to be verified. In case of non-conformances it will be
mentioned in the approval sheet by the concerned persons. Sometime we may have to submit the
revised samples after the required rectifications.

11. Pilot run inspection:
Pilot run denotes the first production garments quality parameters are verified and preventive
measures can be taken. The follow up team should do pilot run inspection to identify the various
defects and it will be rectified in production.

12. In process inspection:
In process means in between any process (or) sewing operation (or) any activities related to execution of an order. We can have procedures for frequency and adequacy. In case of major non- conformities we have to highlight the problems of quality at the right time to the right person without fail. Consistent follow up inspection is a must to confirm that all the required quality procedures are adopted by the concerned units and preventive actions are taken to enhance the performance.

13. Production controlling:
Controlling should be right from the operative level also. Efforts should be taken to control the nonconformities during production. Consistent supervision is essential to control the non-conformances. Periodical quality check should be done after an hour.

14. Shortage problem:
The merchandiser has to identify the shortages of any material that is yarn, fabric, accessories etc. right at the initial stages. After identifying the shortages steps are to be taken for the arrangement of required materials on time. In case of shortages also we have to follow the quality control and quality assurance procedure without fail. Quality of the material should not be compromised.

15. Following quality control procedures:
In some companies written quality procedures are available in quality manual. The merchandiser has to know all the procedures of quality control. In all processes and operations quality procedures should be followed very strictly. It has to inculcate the importance of procedures to subordinates, in house units (or) own units, and sub contractors.

Following quality assurance procedures:
All the required test procedures (as required by the buyer) should be followed very strictly without
partiality. Evidences for testing (test reports) tested samples, tested swatches, tested accessories) should be maintained properly. Before cutting, the merchandiser has to confirm that the concerned unit has got all the required approvals properly from the authorized person.

16. Monitoring the junior activities:
The merchandiser has to monitor his sub-ordinates. He has to teach to the subordinates about the quality procedures. He has to give instructions to them before going for factory visits. He has to discuss the various activities to be executed on a particular day. The merchandiser has to control the activities of the subordinates so that the performance of the followed team is good.

17. Monitoring the activities of in-house unit (or) sub-contractor units:
The merchandiser has to monitor the activities of in-house unit (or) sub-contractor units. He has to confirm that all the quality control procedures and quality assurance procedures are followed up properly by them (or) not. He has to inculcate the importance of adopting quality procedures to attain the planned performance level.

18. Buyer communication:
The merchandiser has to go through the faxes coming from buyers and he has to send reply on time. Sometimes he has to furnish the production status of a particular order to the concerned buyer on time. The below mentioned are some of the duties of buyer communication,
  • Sample execution
  • Amendments
  • Comments on the send samples
  • Sample order sheet
  • Buyer visit
  • Production status
  • Sending sample, swatches, Accessories regarding the approvals.
19. Communication with others:
The merchandiser has to interact with in-house units, sub-contractors, vendors and job workers of various processing. Through proper interaction only we make arrangements for the timely supply of the required materials to the concerned persons. He has to know the production status from various units which will be helpful in proper follow and proper importing.

20. Proper Reporting:
The merchandiser has to furnish (or) best the report to the right person at the right time. He has to give reports for the below mentioned activities
  • Sample execution
  • Approvals
  • Testing procedures
  • Production status
  • Programming
  • Shortage details
  • Inspection details arid status.
  • Production status for meting etc.
  • Report from inspection agencies, testing labs
21. High Lighting:
The merchandiser has to highlight the major problems in merchandising at the right time without fail. Highlighting will facilitate the superiors to take the necessary steps to tackle the problems on time. Proper decision is made due to timely highlighting.

22. Record maintenance:
The merchandiser has to maintain quality records pertaining to various buyer orders. Proper filing should he done, who can utilize the services of subordinates in record maintenance. The below mentioned are some examples.
  • Sample details
  • Sample Inspection Reports
  • Testing Reports
  • Evidence of approvals
  • Proper filing (Buyer wise, order wise)
  • Pattern Approval sheet/size set approval sheet (copy)
  • Pilot run Inspection Report
  • Fabric Inspection report
  • Mid Inspection Report
  • Inspection report from buying office, buying agents and inspection agencies.
  • Test reports from inspection agencies and labs
  • Production status reports
  • Production status reports related to meetings
  • Pre-final inspection reports
  • Final inspection reports etc.
23. Developing samples:
Some buyers will give specifications (or) diagram (or) patterns from which you may have to develop samples. Samples may be fabric with required knit structure (or) garments with required specification. The merchandiser has to consider all the quality parameters related to the samples to be developed. In case of non-conformities in the samples developed, revised samples may be send for approval purpose. It is the duty of the merchandiser to dispatch the developed samples on to the concerned buyers by means of consistent follow-up.

24. Placements of orders:
Priority is given to Approved sub-contractors after evaluation (when the production capacity is not sufficient) order is placed to new manufacturers also orders can be placed to in-house units also. In some companies, merchandiser is accountable (or) responsible to find out the right manufacturers after proper evaluation. At the initial stages small quantity order will be placed. After verifying their performance large quantity orders will be placed. Yarn may be procured by the concerned unit (or) it may be supplied by the supplier (the main manufacturer). In case of CMT order after the confirmation of average piece weight of a particular size, processed fabric is delivered to the concerned unit by the supplier.

25. Taking measures for consistent production:
It is the duty of the merchandiser to monitor the merchandising activities in accordance with the production scheduling. He is accountable for the execution of each and every process (or) an operation within the targeted time. He has to take the necessary step for the consistent production by tackling the problems in merchandising. (e.g.)
  • Quality of yarn
  • Replacing good quality yarn
  • Consistent arrangement for fabric
  • Timely arrangements for the timely supply of accessories.
  • Shortage quantities follow up.
26. Preventive actions:
Detection of defects is not only the duty of merchandiser. He has to take preventive actions to eliminate deviations in all the stages of merchandising.

27. Attending meetings with superiors:
Meetings may be conducted for general discussions about order execution (or) for implementing new systems like ISO (or) it may be a status meeting. In case of production status meeting the production details about various buyers’ order will be collected by the merchandiser from different units and will furnished to superiors. The merchandiser is accountable to answer the various questions raised by the superiors pertaining to the execution of the allotted orders.

Emulating Colors of Animal Kingdom in Textiles

Emulating Colors of Animal Kingdom in Textiles
Dr. Ashok Athalye
G.M.Technical Service,
Atul Ltd (Colors Division), Valsad, Gujarat, India
Email: ashok_athalye@atul.co.in

Human being is the only animal known to wear cloths. The use of textile material for apparel wear by primitive man originated in prehistoric times, probably started in Palaeolithic era, has evolved from mere protection from climatic conditions, providing comfort and maintaining decency to the modern day fashions.

The primitive man initially used material available in nature - animal hides and plant leaves for clothing, to cover and drape his body and gradually developed textile garments made from the natural resources like plant fibres – cotton, jute, flax, etc. and from animal hair – wool and silk. With the industrial revolution of the 20th century development of various man made fibres including synthetic substrates evolved, however, even then almost half of the textile clothing material used worldwide comes from natural fibres. Further, with the growing awareness about environmental concerns, sustainability, impact on carbon footprint and global warming owing to the manufacturing processes of such synthetic fibres the search for development of natural fibres from other renewable resources like polyester based PLA fibres developed from Corn, could gain momentum and it is expected to shift the trend in favour of more use of natural fibres - going back to the Nature !.

The textile substrates are converted into the garment form by process of weaving and knitting and are further processed to make it colorful by adding a colorant – a dye or pigment which imparts color. The coloring compounds generally absorb and reflect light in the visible spectrum and the combinations of which can provide countless numbers of color hues and print patterns and make the garments attractive and appealing. Textile dyeing is an ancient art which predates written records. The method of coloration has also evolved from simple pot dyeing and hand printing to the sophisticated continuous dyeing and computerised digital printing. Initially, natural coloring compounds extracted from various parts of plants – root, bark, leaves, fruits, etc. and from animals or insects was in vogue, however, post 1856 with the development of synthetic dyestuff by Perkin a new era of low cost dyestuff industry and new coloration technique of textiles began. Today, the global synthetic colorant industry is estimated to have reached a level of about 6 bn USD comprising of about 10,000 different synthetic colorants with annual production of over 10 mn MT. With the invention of consistent quality synthetic dyes and simple dyeing methods providing optimum fastness levels, the use of natural dyes declined to an extent of becoming obsolete. However, owing to the growing awareness about the health hazards due to toxicity, mutagenicity and carcinogenicity of many synthetic dyes as well as the non bio-degradable polluting nature of these synthetic colorants and their impact on environmental emission, effluent and the waste, the exploration of natural dyes from renewable resources and environment friendly industrially viable application process has gaining momentum. Again trend is going back to the Nature !.

Color is one of the basic elements of nature that made human living more aesthetic. Colors are closely associated with emotions, festivals and passions of human life. Observing the colors and patterns from the surrounding plants and animals, man began ornamenting his clothing as the civilization progressed and the associated psychological impact of color has evolved the color sense of human being. This probably led to the basic concept of emulating color schemes and patterns of animal kingdom.

Gleaning from the literature available on this topic from various sources and selecting pictures from the web gallery, an attempt is made to provide an overview of this subject in brief.

Animal coloration is considered to be the general appearance of an animal resulting from the reflection or emission of light from its surfaces and there are several reasons why animals have evolved such colors. Animals produce color in different ways and their coloration may be the result of any combination of pigments, chromatophores, bioluminescence and structural coloration. The major factors related to coloration in animal kingdom are considered to be
  • To look attractive
  • To differentiate from others
  • To enhance self satisfaction - feel good factor
  • To warrant specific occasion like group | herd gathering
  • To ensure suitability for work | climate convenience
  • To provide protection
  • To signal or advertising presence
  • To generate structural colors or patterns
On the planet earth “light is life” for existence of all animals and a narrow band of this light consists of visible range for human beings. The psychological properties of the colors - VIBGYOR range of this spectrum, relates to the body, mind and emotions and its essential balance between these three. Researchers like Max Luscher have studied and developed correlation between color and its effect. Given below are major colors observed in animals and their psychological association in humans.

Red Color – has the longest wavelength and is a powerful color having property of appearing to be nearer than it is and grab attention first. It tends to stimulate and raise the pulse rate and relates to the “fight or flight” instinct. It is perceived as demanding and aggressive.
Red Color
Orange Color - it is a combination of red and yellow, it stimulates physical comfort – food, warmth, shelter. It energises mind and renews interest in life. It is anti-depressant and helps lift mood. .
Orange Color
Yellow Color - has relatively long wavelength and provides emotional stimulation for sharing and caring. It also contributes to the expression of thoughts, self confidence and encourages optimism.
Yellow Color
Green Color – is in the centre of the visible spectrum and is considered to be the color of balance, reassurance and comfort. Has a strong affinity with nature, and helps us connect with others. It reduces stress and steadies emotions.
Green Color
Blue Color - is soothing and considered to be the color of the mind which calms the mind and aids concentration. It is the color of peace, clear communication, self-expression and honesty.
Blue Color
Indigo Color – is considered to stimulate intuition and imagination and is a strong sedative which can reduce pain. It is also the color of divine knowledge.
Indigo Color
Violet Color – has the shortest wavelength, relates to introvertiveness and meditation. It helps transform obsessions and combat fears. It has associations with royalty and communicates the finest quality.
Violet Color
Brown Color –is considered to be the color of Mother Earth and most of the grassland animals have varying degree of hues of this color with different patterns.
Brown Color
Grey Color – it is an achromatic color with varying intensity of white and black. It is associated with independence, self-reliance and self-control. Grey is a color of evasion and non-commitment. It also relates to isolation and self-criticism.
Grey Color
To look attractive, some animals including many butterflies and birds have microscopic structures in scales, bristles or feathers which give them brilliant iridescent colors. Other animals including squid and some deep-sea fish can produce light, sometimes of different colors.

Animals often use two or more of these mechanisms together to produce the colors and effects they need. Such different color combinations are emulated by human beings to look attractive.

Colors and their pattern enables an animal to differentiate from others on a special occasion or provide signals for certain behavioural aspects or to communicate information such as warning of its ability to defend itself. Observing such color effects man has also evolved sense of differentiation through the textile clothing that he or she wears.

Some animals develop camouflage designs and patterns for protection | hiding from the predators or enemy and remain undetected which is classified as protective coloration. Camouflage enables an animal to remain hidden from view and thereby protect itself from predators. While some animals use color to divert attacks by startling | surprising a predator e.g. with eyespots or other flashes of color, confusing a predator's attack by moving a bold pattern (such as zebra stripes) rapidly. Some animals are colored for physical protection, such as having pigments in the skin to protect against sunburn, while some frogs can lighten or darken their skin for temperature regulation. Animals colored in these ways can have striking natural patterns.

Protective resemblance is used by prey to avoid predation - includes special protective resemblance called mimesis, where the whole animal looks like some other object, for example when a caterpillar resembles a twig or a bird dropping, while the protective resemblance, called crypsis, is where the animal's texture blends with the background, for example when a moth's color and pattern blend in with tree bark. In variable protective resemblance, an animal such as a chameleon, flatfish, squid or octopus changes its skin pattern and color using special chromatophore cells to resemble whatever background it is currently resting on. The main mechanisms to create the resemblances blending into the background so as to become hard to see; disruptive patterning, using color and pattern to break up the animal's outline, which relates mainly to general resemblance; mimesis, resembling other objects of no special interest to the observer and counter shading, using graded color to create the illusion of flatness.

Similar camouflage coloration by dyeing and printing is used by human beings in military wear for protective clothing to avoid detection from enemy.

Color is widely used for signalling and advertising by animals as diverse as birds and shrimps. Signalling encompasses at least three purposes:
  • To signal a capability or service to other animals,
  • To warn that an animal is harmful
  • To advertising its presence
Signalling enables an animal to communicate information such as warning of its ability to defend itself (aposematism). Animals also use color in advertising | signalling services such as cleaning to animals of other species and to signal sexual status to other members of the same species. Warning coloration is effectively the "opposite" of camouflage. Its function is to make the animal, for example a wasp or a coral snake, highly conspicuous to potential predators, so that it is noticed, remembered, and then avoided.

Human warning signs employ the concept that the nature uses to signal or advertise particular function – for example Khakhi dress of Indian Police, Black or dark navy Blue of commandos and high visible | fluorescent vests of construction workers.

School uniforms and workwear of industrial workman. For protection from harsh climate or weather conditions – we wear thick, warm clothes with dark colors in winter or thin garments with cool, light pastel shades in summer.

Many animals have dark pigments such as melanin in their skin, eyes and fur to protect themselves against sunburn (damage to living tissues caused by ultraviolet light). Brightly colored and patterned animals are more characteristic of tropical areas. This holds true across a wide range of animal groups including insects, reptiles, birds, and mammals.

Structural colors – also called as schemochromes, are based on physical and geometrical properties of optics in terms interference, reflection, refraction and diffraction of light. The phenomenon of structural colors was first reported by Robert Hooke and Isaac Newton.

It is based on production of color by microscopically structured surfaces fine enough to interfere with the visible light, sometimes in combination with pigments: for example, peacock tail feathers are pigmented brown, but their structure makes them appear blue, turquoise, and green, and often they appear iridescent.

It is the result of interference between reflections from two (or more) surfaces of thin films, combined with refraction as light enters and leaves such films. The geometry then determines that at certain angles, the light reflected from both surfaces adds (interferes constructively), while at other angles, the light subtracts. Different colors therefore appear at different angles. When light falls on a thin film, the waves reflected from the upper and lower surfaces travel different distances depending on the angle, so they interfere.

In animals such as on the feathers of birds and the scales of butterflies, interference is created by a range of photonic mechanisms, including diffraction gratings, selective mirrors, photonic crystals, crystal fibres, matrices of nano-channels and proteins that can vary their configuration. Many of these mechanisms correspond to elaborate structures visible by electron microscopy.

Thus, structural colors are developed by microscopically-structured surfaces fine enough to interfere with visible light, sometimes in combination with pigments: for example, peacock tail feathers are pigmented brown, but their structure makes them appear blue, turquoise and green. Structural coloration can produce the most brilliant colors, often iridescent.

Iridescence, is created when extremely thin films reflect part of the light falling on them from their top surfaces. The rest of the light goes through the films, and a further part of it is reflected from their bottom surfaces. The two sets of reflected waves travel back upwards in the same direction. But since the bottom-reflected waves travelled a little further – controlled by the thickness and refractive index of the film, and the angle at which the light fell – the two sets of waves are out of phase. When the waves are one or more whole wavelength apart – in other words at certain specific angles, they add (interfere constructively), giving a strong reflection. At other angles and phase differences, they can subtract, giving weak reflections. The thin film therefore selectively reflects just one wavelength – a pure color – at any given angle, but other wavelengths – different colors – at different angles. So, as a thin-film structure like a butterfly's wing or bird's feather moves, it seems to change color.

Recently, with the growing awareness of environment sustainability aspects and the considerable contribution of dyestuff and pigment industry towards alarming pollution issues, the researchers are working on the development of such structural colors to produce effects and patterns in textile without using coloring compounds.

References :
  1. Kvavadze, Eliso, et al. 2009 30,000-Year-Old Wild Flax Fibers. Science 325:1359.
  2. Peter J.T. Morris and Anthony S. Travis, "A History of the International Dyestuff Industry",
  3. American Dyestuff Reporter, Vol. 81, No. 11, November 1992
  4. http://en.wikipedia.org/wiki/Animal_coloration
  5. Image gallery – www.google.de
  6. Max L├╝scher: „Color - the mother tongue of the unconscious", Capsugel N.V. (1973)
  7. Beddard, Frank Evers (1892). Animal Coloration, An Account of the Principal Facts and Theories Relating to the Colours and Markings of Animals. Swan Sonnenschein, London. 

Properties Changes of Cellulose Due to Mercerization

Cellulose undergoes chemical, physico-chemical and structural modifications
on treatment with caustic soda solution of mercerizing strength. Chemical reactions lead to the formation of alkali cellulose, physical reactions, to a change in arrangement of units of cellulose. The optimum modifications in the properties of cellulose can be manipulated with the selection of proper concentration of alkali, time, tension and temperature during the mercerizing process.

Swelling and shrinkage of cellulose:
When cellulose is immersed in a solution of caustic soda of mercerizing strength, water and alkali diffuses in and the material swells. The fibre hair quickly commences to untwist from its twisted ribbon like form and tends to become cylindrical rodlike surface due to deconvolution. The cross -section of the fibre diminishes, the diameter of the fibre becomes more round. The surface of the nearly cylindrical cotton fibre after mercerizing reflects light more evenly to all sides than the kidney shaped cotton fibre and the fibre surface becomes more lustrous. As the fibre swells, the fibre shrinks in length. Swelling and shrinkage are more when there is no tension in the fibre, but the alteration in cross-section caused by swelling is more when mercerization is carried out under tension. Under optimum conditions each cotton fibre may contract nearly 9% in length and swell nearly 150%. Swelling of the cotton fibre also has a disadvantage. The fibre becomes more compact in its swollen condition. This compacting diminishes the further penetration of caustic soda into the fibre i.e. penetration slows down and mercerization in the fiber's core is lower than on its surface.
Changes of Cellulose Due to Mercerization
Changes of Cellulose Due to Mercerization
Structural modification:
Due to swelling of cellulose in caustic soda solution of mercerization strength, many hydrogen bonds are broken, the plane of molecular chains have been moved apart, molecular structure tends to become decrystallised, the chains or spaces within the cellulose structure become more uniform and the chains of glucose residues have been given a slight twist. Because of the distortion of polymer network and changes in crystalline structure, the process of mercerization is irreversible. Mercerization also affects the size of the crystallites and orientation of the crystalline region and the extent of orientation depends on the tension during mercerization.

Increased luster:
Unmercerized cotton has a general appearance of a flat ribbon with spiral twists, its surface is rough and non-uniform, its cross-section is irregular and ear-shaped while the lumen, the central canal, is broad, irregular and resembles a collapsed tube. All these factors result in less lustre. When a cotton hair is brought into an aqueous solution of sodium hydroxide of 18% (40~ cellulose begins to swell immediately, the hair is elliptical in section in a few seconds, and on further swelling becomes circular and the lumen is practically eliminated. The untwisting of the fibre takes place under effect of swelling and increased alignment and packing of the fibres in the yam also take place.

Lustre also depends on other factors. Mercerization reduces the axial ratio and increase the light scattering within the fibre (transparency) and thus increases the lustre.

Gain in strength:
Mercerization, both slack and with tension, increases the strength uniformity along the fibre length, but mercerized fibre with tension shows greater gain in strength than that of without tension. In practice, the improvements in strength are noticed mostly upon yarn treatments, with fabric the major effect is on the surface only. Mercerization increases the tensile strength of cotton fibres by eliminating the weakest points in the fibre. Mercerization increases the cohesion between individual cotton hairs and this closer embedding of the hairs in the yam not only increases the strength but makes it more uniform in strength and less in diameter.

Increased moisture absorption:
Mercerized celluloses absorb more water, have higher regains and more easily wet out than unmercerized fibres. Due to caustic soda penetration, many hydrogen bonds are broken and it is estimated that the number of available, hydroxyl groups are increased by about 25%. Mercerization, thus decreases the amount of crystalline part or increases the amorphous content of the fibre. This increase in the proportion of amorphous part is directly related to the moisture sorption. Moisture is assumed to be absorbed by suitable groups in the amorphous region and on the surface of the crystallites. When mercerization is carried out under tension, the changes in crystalline portion is comparatively lower than that without tension and hence also the moisture sorption. Standard cotton has moisture content of about 7%, mercerized cotton with tension has about 9% and that of without tension about 11%.

Increased dye adsorption:
Mercerized cotton shows increased depth of shade, increased rate of dyeing and the irregularities due to neps and unripe cotton are less prominent. Generally immature cotton with large lumen responds particularly well to increased light scattering and hence decreased dye uptake.

Mercerization thus lowers the dye costs, savings at 2% depth averaged 40%, while at 6% with the same dyes the average saving is about 60%. Cotton can be causticized or half-mercerized to increase the dye uptake and economics up to 25% may be realised.

Increased reactivity:
The reactivity of mercerized cotton is increased by about 1 I/2 times at lower temperature in comparison to that of unmercerized cotton. The increased reactivity is not so marked when mercerization is carried out under tension. The reactivity ratio is generally referred to as the ratio of copper number of the mercerized to unmercerized samples. The increased reactivity increases dye absorption, moisture absorption and chemical reaction, but at the same time it also accelerates the reaction with acids and oxidising agents and is susceptible to degradation.

Removal of immature cotton:

Mercerization has been recognized as a method for removing immature (dead) fibres to obtain level dyeing effect on cotton fabrics. The dead fibres are underdeveloped and appear as flat or slightly twisted tapes. They are non-crystalline, convolutions are sometimes absent, cell walls are extremely thin and the lumen is collapsed and hence do not contain dye to same extent as matured fibres.

Physical compactness:

Mercerization improves dimensional stability of cotton woven fabrics. When knitted fabrics are compared with respect to their relative openness, temperature increases can be said to improve mercerization because when the goods are bleached and then mercerized, the fabric becomes more dense. However, when unbleached fabrics are mercerized, the fabrics become more open. Mercerization also gives moderate improvement in crease recovery of cotton fabrics as well as some protection against the decrease in tensile strength caused by easy-care finishing.