textile finishing

Finishing:

Textile finishing: textile finishing is a term commonly applied to different processes that the textile materials undergo after pretreatments, dyeing or printing for final embellishments to enhance their attractiveness and sale appeals well as for comfort and usefulness.

The word “finish “ means all the different treatments applied to a fabric to change such things as its

·         Appearance

·         Feel or hand

·         Wear ability or care requirements

Different fabric characteristics required by the consumer:

·         Wear ability, hand, mechanical resistance, easy care, wet ability, wash ability, deform ability, anti bacterial, anti fungal, soil-proof and fire-proof ability.

·         The above mentioned results are achieved by applying respective functional finish.

·          As far as aesthetic looks of the fabric/garment is concerned the aesthetic finishes deal with the

 

Classification of finishes:

Textile finishes are classified in several ways:

According to function:

1.      Aesthetic finishes

2.      Functional finishes

According to the quality:

1.      Temporary

2.      Permanent

3.      Semi permanent

According to type of machinery:

1.      Chemical finishes

2.      Mechanical finishes

Aesthetic finishes:

Aesthetic finishes modify the appearance and / or hand or drape of the fabrics.

·         Filling

·         Mercerization

·         Napping and seeding

·         Plisse

·         Shearing

·         Softening

·         Stiffening

Functional finishes:

Functional finishes improve the performance properties of the fabric, like durability, strength etc.

·         Antimicrobial/ antiseptic

·         Antistatic

·         Crease resistant

·         Durable press

·         Flame resistant

·         Mothproof

·         Shrinkage control

·         Soil release

·         Water proof/ repellant

 Temporary finishes:

 

A finish which is not stable and goes off after the first wash is known as temporary finish and these finishes disappears during subsequent washing and usage.

·         Calendaring

·         Embossing

·         Starching

·         Softening

Permanent finishes:

If the finishing effect in the fabric does not disappear and remains unaffected through all the conditions of wear and washing treatments, then the finish is said to be permanent finish.

·         Sanforising

·         Resin finish

·         Water proof

·         Flame proof

Semi permanent finishes:      

     

A finishing on the fabric is said to be semi permanent finish if it is stable to more than 5 to 10 washes and not afterwards.

·         Schreiner calendaring

·         Buckram finish

Chemical finishes:

Chemical finishes are usually applied to fabric by padding followed by curing and drying. These are also called as wet finishes.

·         Stiff and transparent

·         Flame retardant

·         Soil release

·         Water proof

·         Crease resistance

·         Softening

Description of chemical finishing:

The finishes applied by means of chemicals of different origins, a fabric can receive properties otherwise impossible to obtain with mechanical means.

Softening:

 Softening is carried out when the softness characteristics of a certain fabric must be improved, always carefully considering the composition and properties of the substrate.

Elastomeric Finishes:

 Elastomeric finishes are also referred to as stretch or elastic finishes and are particularly important for knitwear. These finishes are currently achieved only with silicone-based products. The main effect is durable elasticity, because not only must extensibility be enhanced, but recovery from deformation is of crucial importance. After all stresses and disturbing forces have been released, the fabric should return to its original shape.

Crease Resistant or Crease Proofing:

Crease Resistant Finishes are applied to cellulose fibres (cotton, linen and rayon) that wrinkle easily. Permanent Press fabrics have crease resistant finishes that resist wrinkling and also help to maintain creases and pleats throughout wearing and cleaning.

Flame Retardant Treatment:

Are applied to combustible fabrics used in children's sleepwear, carpets and curtains and prevent highly flammable textiles from bursting into flame.

Anti Pilling:

 Pilling is a phenomenon exhibited by fabrics formed from spun yarns (yarns made from staple fibres). Pills are masses of tangled fibres that appear on fabric surfaces during wear or laundering. Fabrics with pills have an unsightly appearance and an unpleasant handle. Loose fibres are pulled from yarns and are formed into spherical balls by the frictional forces of abrasion. These balls of tangled fibres are held to the fabric surface by longer fibres called anchor fibres.

Anti pilling finish reduces the forming of pills on fabrics and knitted products made from yarns with a synthetic-fibre content, which are inclined to pilling by their considerable strength, flexibility and resistance to impact. Anti pilling finish is based on the use of chemical treatments which aim to suppress the ability of fibres to slacken and also to reduce the mechanical resistance of synthetic fibre. 

Non Slip Finish:

A finish applied to a yarn to make it resistant to slipping and sliding when in contact with another yarn. The main effect of non-slip finishes is to increase the adhesion between fibres and yarns regardless of fabric construction, the generic term for these finishes would be fibre and yarn bonding finishes. 

Stain and Soil Resistant Finishes:

 Prevent soil and stains from being attracted to fabrics. Such finishes may be resistant to oil-bourse or water-bourne soil and stains or both. Stain and soil resistant finishes can be applied to fabrics used in clothing and furniture. Scotchgard is a stain and soil resistant finish commonly applied to carpet and furniture.

Oil and Water Proofing:

 Waterproof Finishes -Allows no water to penetrate, but tend to be uncomfortable because they trap moisture next to the body. Recently, fabrics have been developed that are waterproof, yet are also breathable 

Key Features of Waterproof Finish:

1. Intended for use in the fabric of rain- and water-resistant clothing .
2. The type of hydrophobic treatment chosen affects the quality of the garment and its durability during washing or chemical cleaning .
3. Finish is applied by filling the fabric pores with a film-forming compound or by the applying to individual fibers or fabrics of compounds which repel water and have a high surface tension.

Water-Repellent Finishes:

 Water-repellent finishes resist wetting. If the fabric becomes very wet, water will eventually pass through. Applied to fabrics found in raincoats, all-weather coats, hats, capes, umbrellas and shower curtains.

Absorbent Finishes:

Increase fibres' moisture holding power. Such finishes have been applied to towels, cloth diapers, underwear, sports shirts and other items where moisture absorption is important.
Anti Static Finish:Reduce static electricity which may accumulate on fibres. The most common type of anti-static finishes is fabric softeners. 

Mechanical finishes:

Mechanical finishes usually involved specific physical treatment to a fabric surface to cause a change in fabric appearance. This is also known as dry finish.

·         Calendaring

·         Raising

·         Sanforising

·         Milling

Description of Mechanical Finishing:

These involve the passage of the material though machines whose mechanical action achieves the desired effects. A heating process, the purpose of which is usually toe enhance these desired effects, frequently accompanies the these mechanical finishes which will be discussed in detail later in this section are-

Calendaring:

A process of passing cloth between rollers (or "calendars"), usually under carefully controlled heat and pressure, to produce a variety of surface textures or effects in fabric such as compact, smooth, supple, flat and glazed. The process involves passing fabric through a calendar in which a highly polished, usually heated, steel bowl rotates at a higher surface speed than the softer (e.g. cotton or paper packed) bowl against which it works, thus producing a glaze on the face of the fabric that is in contact with the steel bowl. The friction ratio is the ratio of the peripheral speed of the faster steel bowl to that of the slower bowl and is normally in the range 1.5 to 3.0. The normal woven fabric surface is not flat, particularly in ordinary quality plain weave fabrics, because of the round shape of the yarns, and interlacing of warp and weft at right angles to each other. In such fabrics it is more often seen that even when the fabric is quite regular, it is not flat. During calendaring, the yarns in the fabric are squashed into a flattened elliptical shape; the intersections are made to close-up between the yarns. This causes the fabric surface to become flat and compact. The improved paleness of surface in turn improves the glaze of the fabric.

Raising or Napping:

The raising of the fibre on the face of the goods by means of teasels or rollers covered with card clothing (steel wires) that are about one inch in height. Action by either method raises the protruding fibres and causes the finished fabric to provide greater warmth to the wearer, makes the cloth more compact, causes the fabric to become softer in hand or smoother in feel; increase durability and covers the minute areas between the interlacing of the warp and the filling.

Shearing:

Shearing is an important preparatory stage in the processing of cotton cloth. The objective of "Shearing" is to remove fibres and loose threads from the surface of the fabric, thus improving surface finish.

Stabilization:

A term usually referring to fabrics in which the dimensions have been set by a suitable preshrinking operation

Sanforizing or Pre Shrinking:

Sanforizing is a process whereby the fabric is run through a sanforizer; a machine that has drums filled with hot steam. This process is done to control the shrinkage of the fabric. The fabric is given an optimum dimensional stability by applying mechanic forces and water vapor.

Fulling:

The structure, bulk and shrinkage of wool are modified by applying heat combined with friction and compression.

Textile Finishing Processes:

The whole cycle of finishing consists of mechanical and chemical processes, which are used depending on the kinds and end uses of the fabric. Mechanical processes include drying, calendaring, schreinering, embossing, sueding, raisingetc and chemical processes include in the application of special substances on the fabric, impregnation with size, starch, dextrin and other polymeric substances.

Steaming:

A fabric steamer uses steam rather than heat to remove wrinkles . The steam, and slight pressure of the steamer's surface, relaxes the fibers rather than flattening them. Because of this process, using a fabric steamer is gentler on clothing, faster than using an iron, and eliminates scorching.

The fabric steamer is ideal for use on napped fabric, such as velvets and velveteen. A traditional iron will crush the nap, unless used with a needle board, but the fabric steamer doesn't exert pressure, preserving the luxurious look and feel of any material. Even very delicate materials, such as satins and silks, benefit from the gentle care of a fabric steamer.

Sanforizing:

It is a process whereby the fabric is run through a sanforizer; a machine that has drums filled with hot steam. This process is done to control the shrinkage of the fabric.

Tentering:

It is the mechanical straightening and dying of the fabric. Tenter fames hold the fabric with special pins. The chain is spread apart to the desired width of the fabric. The fabric is moved through dying units. Later the fabric is rolled on cylinders.

Perforating and Slitting:

The nonwoven bonded fabrics produced are too stiff and are, therefore, unsuitable for clothing. This is because the individual fibers are not free to move in relation to one another, as are threads in woven or knitted fabrics. Perforating and slitting are two methods practiced to improve the fall or drape of nonwoven bonded fabrics

Heat Setting:

Heat-setting is a heat treatment by which shape retention, crease resistance, resilience and elasticity are imparted to the fibres. It also brings changes in strength, stretchability, softness, dyeability and sometimes on the colour of the material. All these changes are connected with the structural and chemical modifications occurring in the fibre.

This operation is crucial for fabrics made of synthetic fibres (PE, PA, elastomers), for triacetate, and partly for PAC fibres (setting), since it grants excellent dimensional stabilisation and creaseproof properties, maintained till the fabric is exposed (by air blowing) to temperatures exceeding the heat setting one (after being treated with water at a temperature above the second order glass transition temperature, i.e. 80-85°C for acrylics).

Heat setting is carried out on gray fabrics (scarcely applied), on scoured fabrics (frequently applied) and on dyed fabrics (scarcely applied). The process grants excellent dimensional stability and good crease-proof properties. As far as operating conditions are concerned, the fabric must be treated in accurately controlled moisture and temperature conditions.

Heat setting of Some Fibers

Fibre	Min T. °C	Max. T. °C	Time in sec
Polyester (PE)	170	210	15-50
Polyamide PA 6.6	170	210	15-40
Polyamide PA 6	160	180	15-40
Triacetate	160	180	15-40
Acrylic (PAC)	160	180-200	15-40
Elastomers	170	180-200	15-40

Textile Fabric Finishing:

Fabric direct from the loom is unattractive. To make the fabric attractive and acceptable to the consumer several finishing processes are applied. Sometimes special finishes are also applied to the fabric to make it serviceable for particular end use.

Finishing Defects:

The defects which are occurred in finishing process are enlisted below:

1. Unwanted marks on fabric
2. Decolorized patch on fabric
3. Pin holes
4. Sanforize Pucker
5. Bowing
6. Pilling
7. Water Spots
8. Cuts or Nicks
9. Seam Tears
10. Soil
11. Streaks
12. Inadequate Pressing
13. Pressing Producing Shine on Fabric
14. Loose Threads
15. Askewed or Bias
16. Folding Defects
Unwanted marks on fabric: 
Oily stains with dust adhered to surface which makes the stains more prominent and difficult to remove, due to contact with oil or grease covered exposed machine parts, careless handling could be another cause.

Decolorized patch on fabric: 
Caused due to

• Chemical spillage on fabric.
• Localized excess bleaching.
• Localized excess enzyme wash.
• Can be result into weakening of the fabric.

Pin holes :

• Holes along selvage caused by pins holding fabric while it processes through tenter frame.
• Major defect if pin holes extend into body of fabric far enough to be visible in the finished product.

Sanforize Pucker :

• Results from uneven wetting out on sanforize.
• Usually caused by defective spray heads.
• Fabric will appear wavy or puckering when spread on cutting table.
• Difficult to detect during inspection on inspection machine with fabric under roller tension.

Bowing :

• Usually caused by finishing.
• Woven filling yarns lie in an arc across fabric width; in knitsthe course lines lie an arc across width of goods.
• Establish standards of acceptance.
• Critical on stripes or patterns; not as critical on solid color fabrics.

Pilling: 

• Pilling is a common fabric defect occurring on knitted and woven fabrics.
• In producing a yarn, long fibers tightly-twisted produce a serviceable yarn. When short stable fibers are mixed into the yarn the result is a yarn that will not hold together. The short staple fibers will separate from the yarn and curl up in a ball, forming what is referred to as a pill.
• Pilling is accentuated by the friction of normal wear, washing and routine dry cleaning.

 Water Spots :

• Usually caused by wet fabric being allowed to remain too long before drying; color  migrates leaving blotchy spots.

 Selvage Torn : 

• Usually caused by excessive tension while processing through tenter frames.

 Cuts or Nicks :

• Caused by indifferent handling of scissors. snips or mechanical trimmers.

  Seam Tears :

• Frequently caused by the turning equipment used toreverse garments in finishing.

   Soil :

• Caused by oil, grease or dirt. Often times originating from a dirty work area or machinery not properly cleaned

  Streaks :

• Markings caused by some types of turn boards or defectively finished trimming.

   Inadequate Pressing :

• Caused by excessive heat or pressure resulting in poor pleating, fullness or twisting of a seam on garment surface.

  Pressing Producing Shine on Fabric: 

• Usually caused by excessive heat or incorrect type of pressing surface.

  Loose Threads :

• Loose threads will get wound on guide rollers forming ridgesin the processing machines and cause creases at these places.
• Also loose threads can cause problems of Dye /Print transfer in a padding / Printing application

   Askewed or Bias :

• Condition where filling yarns are not square with wrap yarns on woven fabrics or where courses are not square with wale lines on knits.

 Folding Defects :

• Garment not Folded to Specifications
• Garment not Folded with proper Materials:
• Cardboard, tissue or other specified packaging materials omitted
• Garments not Buttoned, Flys not
• Closed, Incorrect Number of Pins 

                       

Defect of Fabric Finishing: 

A series of processing operations applied to gray fabrics to enhance their appearance and hand, properties and possible applications. 

• Play a fundamental role for the commercial excellence of the results of textiles. 
• The most simple form of finishing is the ironing or pressing on the fabric. 
• In finishing, the fabric is subjected to mechanical and chemical treatment in which its quality and appearance are improved and its commercial value enhanced.  
• Physical finishing techniques (dry finishing processes) or chemical finishing methods (wet finishing) are used.

 

Finishes on Denims:

1.         Denim washing is the aesthetic finish given to the denim fabric to enhance the appeal and to provide strength.

2.         Dry denim, as opposed to washed denim, is a denim fabric that is not washed after being dyed during its production.

Leather Finish:

•           Leather fabric carries natural textures.

•           Some has scars where as others show a grainy surface.

•           Few of them have velvety appearance and some marbled or creased look.

•           Many of them are given textures artificially, such as embossed leather.

Object of Finishing:

•           To enhance the suitability of the fabric for end use.

•           To improve appearance and sale appeal for comport and utility.

  More specifically, objects of finishing can be-

•           To improve the appearance of the fabric.

•           To improve the feel of the fabric.

•           To cover faults in the original fabric.

•           To improve wearing qualities of fabric by making it shrink or crease resistant.

•           To set garment shape. E.g. Durable press.

•           To import special properties to the fabric for special end uses such as waterproofing, flame-proofing etc.

•           To strengthen the fabric by coating or laminating.

•           To produce novelty effects e.g. organdie fabrics by parchment sing.