FINISHING

Ashish Kumar Gupta

OBJECTIVE

Finishing is what makes fabrics more suitable for

their intended end use

Finishes have such a profound effect on fabrics

that the same greige goods can be finished to

produce several types of fabrics (Muslin, chintz,

and plisse, imitation seersucker) can all be made

from the same construction of cotton cloth greige

goods.

CLASSIFICATION

Aesthetic finish (modify the appearance ,hand

,drape of fabrics)

Functional finish (Which improves the

performance of the fabric)

CLASSIFICATION

Chemical finishing (Wet finishing)

Mechanical finishing (Dry finishing)

CLASSIFICATION

Permanent(Permanent finishes usually involve a chemical change in fiber structure and do not change or alter throughout the life of a fabric.)

Durable(Durable finishes usually last throughout the life of the article, but effectiveness becomes diminished after each cleaning, and near the end of the normal-use life of the article, the finish is nearly removed.)

Semi durable(Semi durable finishes last through several launderings or dry cleanings and many are renewable in home laundering or dry-cleaning.)

Temporary (Temporary finishes are removed or substantially diminished the first time an article is laundered or dry-cleaned.)

MECHANICAL FINISHING

FELT

Felt is a non-woven cloth that is produced by matting, condensing and pressing woolen fibers. While some types of felt are very soft, some are tough enough to form construction materials. Felt can be of any color, and made into any shape or size.

Felt is made by a process called wet felting, where the natural wool fiber is agitated by friction and lubricated by moisture (such as soapy water).

This "wet" process uses the inherent nature of wool and other animal hairs, because the hairs have scales on them which are directional. The hairs also have kinks in them, and this combination of scales is what reacts to the stimulation of friction and causes the phenomenon of felting. It tends to work well with woolen fibers, as their scales, when aggravated, bond together to form a cloth.

WOOL FIBER STRUCTURE

FULLING

Fulling, Process that increases the thickness and compactness of woven or knitted wool by subjecting it to moisture, heat, friction, and pressure until shrinkage of 10–25% is achieved.

Shrinkage occurs in both the warp and weft see weaving), producing a smooth, tightly finished fabric that is light, warm, and relatively weather proof.

Fulling is the process of taking a cloth made of wool (could be made by felting, knitting, weaving, crocheting, etc.) and then using vigorous methods to make the cloth become a felt. It is the late stages of the feltmaking process.

As a result , the fabric has a fuller, more compact body.

WEIGHING

Weighting of Silk:The process of increasing the

weight of the silk material is known as weighting

of silk.

It will improve the hand and drape of the fabric.

Excessive use of the metallic salt can weaken the

fabric

OBJECT OF SILK WEIGHTING:

After the processing of silk material, it loses

about 25% of its weight particularly after

degumming.

This loss in weight leads to a great loss of money

since they are very expensive.

To compensate the loss, some weight is

artificially added to the material by chemical

means.

During degumming of silk, a weight loss of

25% is normally observed in case of silk fabrics.

Owing to the expensive nature of silk, it is

necessary to compensate the weight loss.

DECATIZING

By this process high-quality wool and woollen-

blend fabrics receive a permanent fixing.

The wool fabrics acquire important basic

qualities like a flowing drape, crease resistance

and a discreet glaze finish. Decatizing takes place

through the application of steam under pressure.

PURPOSE OF DECATIZING

Improvement of the texture through added

humidity

Moderation or setting of the glaze or sheen

Dye-fast finish

Wet fixing in length and width

CALENDARING

Purpose is to flatten fabric thereby increasing

luster and smoothness by the action of heat and

pressure.

The finish is obtained by passing the fabric

between heated rotating rollers when both speed

of rotation and pressure applied are variable.

The surface of the roller can be either smooth or

engraved to provide the appropriate finish to the

fabric.

The rollers may be made of various material from

hardened steel to elastic thermoplastic.

PROCESS

Fabric is passed between rolls under heavy

pressure.

One roll is usually metal and the other is usually

covered with paper or fabric.

The temperature ranges from cold to 500oF,

while pressure may range from 200 lbs/in2 to

2500 lbs / in2.

Moisture in the form of water or steam may be

used to achieve a desired luster.

KEY COMPONENTS:

Composition of calender rolls

Pressure

Heat

Moisture

FABRIC CHARACTERISTICS:

Becomes thinner, less permeable, has more cover and luster.

Too much pressure makes the fabric papery.

Excessive heat and pressure will cause too much luster.

Scarred surface rolls will imprint the defect onto the fabric.

Effect is usually permanent on thermoplastic fibers.

Resins required to be used to make calendering durable on cellulosic fabrics. Without the resin the effect lasts only one laundering.

GLAZING

Glazing calendering produces a highly glazed, polished effect on one side of a fabric surface.

The calendar machine used for this purpose is called a friction calendar or chasing calender.

One cylinder of the friction calender is made of highly polished steel.

It rotates at a speed much higher than that of the fabric passing around and between the rollers, thus, literally polishing the fabric surface.

Glazing imparts a smooth, stiff, highly polished surface to such fabrics as chintz. It is achieved by applying such stiffeners as starch, glue, shellac, or resin to the fabric and then passing it through smooth, hot rollers that generate friction.

Resins are now widely employed to impart permanent glaze. Ciré (from the French word for waxed) is a similar process applied to rayons

SCHREINERIZING OR SILK FINISHING

Is an inexpensive method for imparting lusture to low priced cotton.

Steel rollers finely engraved with lines and exerting a pressure of 4500 pounds,impress on the fabric diagonal ridges.

Bowls contains series of fine embossed lines at an angle of 30°(warp wise)

Reflection of light from these ridges give the fabric a lustrous effect somehow similar to that produced by mercerization.

It is not permanent and disappears on repeated laundering.

Effect can be made permanent by the use of thermoplastic fabricor, in the case of cotton, by the use of a resin finish.

This finish is particularly popular on curtains and drapes becauseof the silk-like appearance; this type of finish is very common inlocal Kameez Shalwar suits.

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EMBOSSING

Embossing produces a three-dimensional design

on the fabric.

This is done on a special embossing calender in

which the roller cylinder is engraved with the

embossing design.

The pattern is thus pushed or shaped into the

cloth when the fabric passes between the rollers.

MOIREING

The moire effect is an optical effect produced

when a tightly woven fabric with very fine yarns

is subjected to a surface pressure that distorts

the weave structure by yarn movement or yarn

self compression. It resembles the water marking

effect.

The moire effect can only be produced when the

fiber being treated is capable of being

deformed.eg wool does not produce bold patterns

because it has good resilience and springs back

after deformation.

CIREING

This process may be applied to silk, rayon,or

nylon woven fabrics-usually satins and taffetas-

but may also be used on knitted goods.

Wax or another appropriate compound is applied

to the fabric ,followed by hot calendering. The

result is a supergloss almost metallic in

appearance fabric.

BEETLING

Beetling is a common finishing process for linen.

The yarns are flattened by the impact of wooden

mallets.

The hammering actually closes the weave and

gives cloth a firm ,flattened ,lustrous

appearance.

CROPPING

It is cutting the surface hair from the fabric to

give a smooth appearance, often used on woolen

goods where the removal of surface hair by

singeing process is not possible.

RAISING

Raising is a technique to give brushed or napped

appearance.

It is achieved by teasing out the individual fibers

from the yarns so that they stand on the surface.

This is achieved in modern machines by using

hooks or bent steel wires to tease the fibers from

the surfaces of the fabric.

Raised or napped fabrics have a softer hand and

provide better insulation then the same material

unnapped, therefore widely used in blankets,

sleepwear etc

NAPPING

A napped fabric is a fabric with a "nap", that is, a

fabric with a textured surface that looks different

depending on how it is viewed or positioned.

Notes to be given

SANDING ,SUEDING/ EMERIZING

In order to obtain a suede like surface, Fabric

may be given a sanding by passing them through

a series of emery covered rollers.

The process produces a soft nap.

CREPE AND CRINKLED EFFECTS

Permanent crepe effects are obtained by using

hard twisted yarns in the weaving process.

Crepe surfaces can also be produced by certain

finishing process, But the results are not always

satisfactory.

A finishing method imprints a crinkled effect by

means of engraved rollers, similar to that

produced when the thumbnail is drawn across

tissue paper.

The finish disappears with repeated washing.

CONT…

In another finishing method, caustic soda is

impressed on cotton fabric in the form of figures

and strips.

The fabric is then washed. The part imprinted

with the soda shrinks and the other part puckers.

A similar effect is obtained by using strips of wax

in place of the caustic soda.