1. Assignment Topic: Textile Finishing
Textile Finishing
Finishing is a term which usually refers to the treatments given on a
textile materials to enhance quality, after coloration but before the
textiles are cut and sewn into garments, house hold textiles or other
products.
Dyeing and
Printing ←
Textile
Finishing →
RMG and
MKT
In textile manufacturing, finishing refers to the processes that convert
the woven or knitted cloth into usable materials and more specifically to
any process performed after dyeing the yarns or fabric to improve the
look, performance or hand feel of the finished textile or clothing.
Textile finishing depend on the same factors which are given
below:
1. The physical properties of fibers.
2. The type of fibre and its arrangement in yarn and fabric.
3. The capacity of fibres to absorb chemicals.
2. Objectives of textile finishing:
Finishing is the beautification of fabric. It has huge objectives and it
change according to consumer demands. But main object is to improve
the attractiveness or serviceability of fabric. Without this objective it has
some more objects which are given below.
Objectives of textile finishing are given below:
To change the surface characteristics of textile materials.
To increase life and durability of textile materials.
To set the chemicals into the textile materials.
To impart new characteristics/properties of textile materials such
as flame retardant, water repellent or water proof finishes.
To set the fabric, so that it can be maintained its shape and
structure.
To meet up specific end uses.
3. Classification of textile finishes:
Finishing processes are so varied that it is difficult to classify them. For
cotton, several finishing processes are used widely, but they are so
varied in technique that it is difficult to group them together. The
finishing processes may be broadly classified into two groups: Chemical
finishing and Mechanical finishing. Mechanical finishing is considered a
dry operation even though moisture and chemicals are often needed to
successfully process the fabric. The mechanical finishes include
calendering, emerising, compressive shrinkage, raising, brushing and
shearing or cropping. Chemical finishing or ‘wet finishing’ involves the
addition of chemicals to textiles to achieve a desired result. In this
finishing process water is used as the medium for applying the
chemicals. Heat is used to drive off the water and to activate the
chemicals. Some finishes combine mechanical processes along with the
application of chemicals.
Another method of classification is to classify finishes as temporary and
permanent or durable finishes. In fact, no finish stands permanently till
the material is serviceable, hence a more accurate classification would
be temporary or durable.
Some of the temporary finishes are:
#Mechanical: calender, schreinering, embossing, glazing, breaking,
stretching, etc.
#Filling: starch, china clay and other mineral fillers
#Surface application: oil, different softeners and other finishing
agents.
4. Some of the durable finishes are:
#Mechanical: compressive shrinkage, milling of wool, raising and
cutting processes, permanent setting, etc.
#Deposition: synthetic resins—both internal and external, rubber
latex, laminating, etc.
#Chemical: mercerisation, perchmentising, cross-linking agents,
water repellent finish, fire-resistant and fireproofing finishes, shrink
proofing of wool, etc.
We can also classifiedtextile finishing in the following
ways:
Physical finishing
Functional finishes of textile
Chemical finishes
Plasma finishing
Coated finishing
5. All finishing processes are described briefly:
Physical Finishing:
Physical finishing methods for textiles include optical finishing,
brushing and napping, softening, shearing and compacting of the textile
structure.
Optical finishes:
Lustre may be imparted to a fabric by physical means. The techniques
basically involve flattening or smoothing the surface yarns using
pressure. Beating the fabric surface or passing the fabric between hard
calendering rolls under pressure and with some friction will tend to
flatten out the yarns and lower light scattering by the fabric surface,
thereby improving reflectance and lustre. Lustre may be improved
further if the calendering rolls are scribed with closely spaced lines
which will be imprinted on the fabric to reinforce light striking and
reflecting from the fibre surface. Similar techniques can be used to
impart optical light interference patterns on the fabric. Thermoplastic
fibres which can deform under heat and pressure can most readily be
modified to impart lustre.
Brushing and napping:
Physical delustring of a fabric, as well as bulking and lofting of the
fabric can be achieved by treatments which roughen the fibre surface or
raise fibres to the surface. Fibre raising processes, such as brushing and
napping, involve the use of wires or brushes which catch yarns in the
textile structure and pull individual fibres partly from the yarn structure.
The resulting fabric is warmer, softer and more comfortable.
During calendering or beating of a fabric interaction between individual
fibres within yarns may be lessened and the textile structure softened.
Also, when a smooth textile structure free of raised surface fibres or
hairiness is desired, the fabric may be sheared by passing the fabric over
sharp moving blades or by passing the fabric over a series of small gas
6. jets which singe and burn away raised fibres.
Compacting:
During the fabric formation processes, tremendous stresses are applied
on textile materials. Such stresses can be controlled by drying the
finished fabric with or without tension on a stenter frame, which controls
the width of the fabric and the tension on the fabric during the drying
process. A second method involves compression of the fabric structure,
as in the Sanforizing process. In this process, the fabric and backing
blanket (rubber or wool) is fed between a feed roller and a curved
braking shoe, with the blanket kept under some tension. The tension on
the blanket is released after passing the fabric and blanket between the
roller and braking shoe. The net result is the compaction of the fabric.
Such a simple technique permits garment making with finished textile
goods to be without fear of excessive shrinkage on laundering.
Protein hair fibres, such as wool, and thermoplastic fibres, such as
polyester, can also be compacted. The scale structures on protein fibres
entangle and stick on agitation, particularly in the presence of moisture.
The resulting ‘ratcheting’ effect causes the fibres to compact and felt.
Many processes for wool take advantage of this effect, and nonwoven
felt structures are produced by this method.
Compaction of the thermoplastic structure occurs when the fibres are
raised to near their softening point. At a sufficiently high temperature,
the fibres shrink and contract and achieve a stable structure, causing
compaction of the textile structure.
Functional Finishes:
Various functional fabric properties may be improved by using suitable
chemical and/ or physiochemical techniques. The latter includes coating
and exposure to high-energy sources and are gradually superseding
conventional wet chemical methods. The use of polymers instead of
simple chemicals is increasing in order to improve multiple functional
7. properties simultaneously. The properties of fabrics and fibrous
materials are altered to improve their performance with regard to various
physical, chemical and/ or biological agents and influences. Such
property modifications include: resistance to wrinkling, fire, soils and
stains, water, microorganisms and insects, light, heat and cold,
shrinkage, air pollutants and chemical agents, mechanical changes
caused by abrasion, pilling and various types of deformation and build-
up of static charge. A few finishing processes which improve functional
textile properties are listed below along with applicability or demand for
specific fibre types:
1. Wrinkle resistance or resiliency—for cellulosic fibers and their
blends with synthetics
2. Flame retardancy—for most natural and synthetic fibers
3. Absorbency—usually to impart hydrophilicity to synthetic fibres
4. Soil release—primarily for synthetic fibers and their blends
5. Repellency (soil and stain)—primarily for synthetic fibres
6. Repellency (water)—primarily for cellulosic fibres
7. Resistance to microorganisms—primarily for cellulosic fibres, all
fibres for medical purposes
8. Resistance to insects—mostly for wool fibres
9. Shrinkproofing—primarily for cellulosic and wool fibres
10. Resistance to static charges—primarily for synthetic fibres
11. Resistance to pilling—high tenacity synthetic fibres and their
blends
12. Abrasion and wear resistance—primarily for cellulosic fibres and
their blends
13. Resistance to UV light, heat and pollutants—for most natural and
synthetic fibres, especially polyamide fibres
14. Thermal conductivity (hot or cold, thermal comfort)—all natural
and synthetic fibres
The physicochemical or chemical methods are employed for the
application of functional finishes on textile materials. The former
includes application or irradiation of high energy, coating,
insolubilisation or deposition and microencapsulation.
8. Chemical methods include polymerisation, cross-linking and resin
treatment, covalent formation and ion-exchange/chelation.
Chemical Finishes of Textile:
When chemicals are used to change fabric properties, they must be
applied uniformly throughout the fabric and fibers. Chemical finishing
steps involve applying a chemical solution with a suitable applicator,
removing water (drying) and heating the fabric to a temperature that
activates the chemical (curing). Actually the proper formulation of
chemical finishes is not easy. Several important factors are to be
considered before the finalisation of a formulation; a few are as follows:
1. The type of textile (fibre composition of the fabric and its
construction)
2. The performance requirements (extent of effect and durability)
3. The economics of the formulation
9. 4. Availability of machinery and associated process restrictions
5. Procedure requirements
6. Environmental consideration
7. Compatibility and interactions of finishing components.
10. Chemical finishes should meet the following
requirements:
1. Low-cost product and process
2. Stable during storage and application in terms of pH, temperature
and mechanical stress
3. Compatible with other finishes
4. Adaptation to customer requirement and substrate variation
5. Suitable for all kind of fibres and all textile forms such as yarn,
woven or knit fabric, garment, nonwovens, etc.
6. Satisfactory stability during washing and dry cleaning
7. Should not hamper important textile qualities
8. On application should be distributed evenly on the fabric and
fibre surface
9. No yellowing of white goods or colour change of dyed goods.
10. Easy correction of finishing faults
11. Nontoxic and ecofriendly
12. No release of volatile organic compounds
13. Biodegradable.
Usually, several types of finishes are combined mostly in one bath
(only one application and drying process) for economical reasons.
This is often the hardest challenge of chemical finishing. First, all
components of the finish bath must be compatible.
11. Coated Finishing:
The coated fabrics are becoming more popular day by day primarily
for technical textiles as water repellency, air permeability, etc.
Coating can be applied on any fibrous substances including glass,
polyethylene and polyethylene in woven, knitted or nonwoven form.
Woven coated fabrics are known for high strength, while knitted
coated fabrics have high elongation properties. Insolubilisation of
chromium compounds inside the textile materials can impart
resistance to UV light or sunlight. Antimicrobial properties can be
improved by microencapsulation with quaternary ammonium salts.
Conclusion:
Chemical finishing is always an important component of textile
processing because it makes textile materials marketable and user-
friendly. In recent years, there has been a growing trend towards ‘high-
tech’ textile products. As the use of high performance textiles has
grown, the need for chemical finishes to provide the fabric properties
required in these special applications has grown accordingly.
12. References:
1. Textile Processingby J L Smith
2. Textile Processingand Properties by Tyrone L. Vigo
3. Chemistry & Technology of fabric preparation & finishing by Dr. Charles
Tomasino.
4. Principles of Textile Finishing by A K Roy Choudhury.
