Introduction
In the textile field, the raw textile product doesn't use without finishing the
process. Raw goods are hard and stiff, wear and tear properties are not good. The hand feel is also harsh and very rough.
Some special finishes for natural fibers in the textile industry
There
are many types of finishing processes in textile goods. For natural fiber below
the special finishing process is done. Such as-
Bio-polishing
Bio polishing is also
called bio finishing, is a finishing process applied to cellulose textiles that
produce permanent effects from the use of enzymes. Bio polishing removes
protruding fiber and slubs from fabrics, significantly reduces pilling, softens
fabric hand, and provides a smooth fabric appearance, especially for knitwear
and as a pretreatment for printing. In denim processing, biopolishing can
reduce or eliminate abrasive stone and aggressive chlorine treatments. Bio polishing is not only useful for cotton but also for regenerated
cellulose fabrics, especially for lyocell and microfibre articles. The enzymes
may be incorporated into detergents to remove protruding surface fibers. This
improved color retention is achieved after multiple launderings. The
disadvantages of biopolishing are the formation of fiber dust, which has to be
removed thoroughly, the reproducibility of the effect, and in the worst case,
loss of tear strength.
Mercerization
Mercerization is a process by which cotton fabric
and thread give silk-like luster and strengthen them. The process is applied
to cellulosic materials like cotton or hemp. The process is done by the
solution of 55–65 ° Twaddle sodium hydroxide. A further possibility is
mercerizing during which the fabric is treated with a sodium hydroxide solution
to cause swelling of the fibers. This results in improved luster, strength, and
dye affinity. Cotton is mercerized under tension, and all alkali must be washed
out before the tension is released or shrinkage will take place. Mercerizing
can take place directly on grey cloth, or after bleaching.
Raising finishing
A raising card is used to raise cloth. It is the
technique used to produce the nap of cloth. Originally, only woolen cloth
was raised, but now flannelette and other cotton fabrics are also raised.
Raising is one of the last steps in the finishing process for cloth. It teases
out the ends of the fibers in the cloth to produce a nap. The raising was first
using the dried fruit pod of a teasel plant, then technology moved on and
raising cards were created. A raising card is a brush with metal bristles,
similar to hand cards, and to the original teasel pod. The process was
mechanized during the industrial revolution, and the raising machine looks and
works much like the large carding machines, in that it has a large main roller
with several small ones positioned around it. The small ones rotate quickly, in
either the same direction or opposite of that of the cloth. After the raising
process, the nap is uneven. In order to gain an even surface, the nap is then
sheared, or cut, to the desired height. There are two types of raising machine;
Teasel machine and Card-wire machine. The speed of the card-wire raising machine
varies from 12-15 yards per minute, which is 20-30% higher than that of
teasel-raising. That is why the card-wire raising machine is widely used.
Peach finishing
Peach finishing a soft hand
(feel) is usually obtained by machine sanding the fabric lightly; it can be achieved
with chemical or laundry abrasion. Peaching
is simply a process that involves sanding the fabric. The technique can be
applied to just about any type of fiber, although it does seem to work more
effectively with natural materials. After the fabric is woven, sections of the
material are dipped in chemical compounds that permeate the fabric. The
sections are then stretched taut and left to dry. Peach Finish subjects the fabric (either
cotton or its synthetic blends) to emery wheels, making the surface velvet-like.
This is a special finish used mostly in garments.
Fulling or waulking
Fulling is also known
as tucking or walking. It is derived from Scottish waulking,
is a step in woolen cloth-making that
involves the cleansing of cloth (particularly wool) to eliminate oils, dirt, and other impurities, and to make
it thicker. The practice died out with the modernization of the industrial
revolution. Fulling involves two processes: scouring and milling (thickening).
Originally, fulling was carried out by the pounding of the woolen cloth with a
club, or the fuller's feet or hands. However, fulling was often carried out in
a water mill, followed by
stretching the cloth on great frames known as tenters, to which it is attached
by tenterhooks.
In
Roman times, fulling was conducted by slaves working the cloth while ankle-deep
in tubs of human urine. Urine was so important to the fulling business
that it was taxed. Stale urine, known as wash, was a source
of ammonium salts and assisted in cleansing and whitening the cloth. By
the medieval period, fuller's earth had been introduced for use in
the process. This is a soft clay-like material occurring naturally as an
impure hydrous aluminum silicate. It was used in conjunction with
wash. More recently, soap has been used.
The second function of fulling
was to thicken cloth by matting the fibers together to give it strength and
increase waterproofing (felting). This was vital in the case of woolens,
made from carding wool, but not for worsted materials made
from combing wool. After this stage, water was used to rinse out the
foul-smelling liquor used during cleansing. Felting of wool occurs upon
hammering or other mechanical agitation because the microscopic barbs on the
surface of wool fibers hook together, somewhat like Velcro.
Decatising
Decatising is also known as crabbing, blowing, and
decatising, which is the process of making permanent a textile finish on a cloth
so that it does not shrink during garment making. The word comes from the
French décatir, which means to remove the catie or finish of the wool. Though
used mainly for wool, the term is also applied to processes performed on
fabrics of other fibers, such as cotton, linen, or polyester. Crabbing and
blowing are minor variations on the general process for wool, which is to roll
the cloth onto a roller and blow steam through it.
Decatized wool fabric is interleaved with a cotton,
polyester/cotton, or polyester fabric and rolled up onto a perforated Decatising drum under controlled tension. The fabric is steamed for up to ten
minutes and then cooled down by drawing ambient air through the fabric roll.
The piece is then reversed and steamed again in order to ensure that an even
treatment is achieved.
There are several quite different types of wool Decatizing machines including batch Decatizing machines, continuous Decatizing
machines, wet Decatising machines, and dry Decatizing machines.
Calendaring
Calendaring is a finishing
process used to smooth, coat, or thin a material. With textiles, the fabric is
passed through calendar rollers at high temperatures and pressures. It is used
on fabrics such as moiré to produce its watered effect and also on cambric and
some types of sateens. In preparation for calendaring, the fabric is folded
lengthwise with the front side, or face, inside, and stitched together along
the edges. The fabric can be folded together at full width, however, this is
not done as often as it is more difficult. The fabric is then run through
rollers that polish the surface and make the fabric smoother and more lustrous.
High temperatures and pressure are used as well. Fabrics that go through the
calendaring process feel thin, glossy, and papery. The wash durability of a
calendared finish on thermoplastic fibers like polyester is higher than on
cellulose fibers such as cotton. On blended fabrics such as Polyester/Cotton,
the durability depends largely on the proportion of synthetic fiber components
present as well as the amount and type of finishing additives used and the
machinery and process conditions employed.
Sanforization
Sanforization
is a process that is mainly applied to cotton fabrics and textiles which is made
from natural or chemical fibers. It is a method of stretching, shrinking, and
fixing the woven cloth in both length and width before cutting and producing,
to reduce the shrinkage which would otherwise occur after washing. The cloth is
continually fed into the sanforizing machine and therein moistened with either
water or steam. A rotating cylinder presses a rubber sleeve against another,
heated, rotating cylinder. Thereby the sleeve briefly gets compressed and
laterally expanded, afterward relaxing to its normal thickness. The cloth to
be treated is transported between the rubber sleeve and heated cylinder and is
forced to follow this brief compression and lateral expansion, and relaxation. The
greater the pressure applied to the rubber sleeve during sanforization, the
less shrinking will occur once the garment is in use. The process may be
repeated. The aim of the process is a cloth that does not shrink significantly
during production, cutting, ironing, sewing, or especially, by wearing and
washing the finished clothes. Cloth and articles made from it may be labeled
to have a specific shrink-proof value e.g., of under 1%.
Crease resistance
Crease formation in woven or knitted fabric composed of
cellulose during washing or folding is the main drawback of cotton fabrics. The
molecular chains of the cotton fibers are attached to each other by weak
hydrogen bonds. During washing or folding, the hydrogen bonds break easily, and
after drying new hydrogen bonds form with the chains in their new position and
the crease is stabilized. If crosslinks between the polymer chains can be
introduced by cross-linking chemicals, then it reinforces the cotton fibers and
prevents the permanent displacement of the polymer chains when the fibers are
stressed. It is therefore much more difficult for creases to form or for the
fabric to shrink on washing.
Anti-microbial finish
An anti-microbial finish, causes a piece of fabric to inhibit the growth of microbes. The humid
and warm environment found in textile fibers encourages the growth of microbes. Infestation by microbes can cause cross-infection by pathogens and
the development of odor where the fabric is worn next to the skin. In addition,
stains and loss of fiber quality of textile substrates can also take place.
With an aim to protect the skin of the wearer and the textile substrate itself,
an anti-microbial finish is applied to textile materials.
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