Textile Finishing

TEXTILE FINISHING

• Any operation (other than preparation and coloring) that improves the appearance and/or usefulness of fabric after it leaves the loom or knitting machine. • Finishing is the final series of operations that produces finished textile fabric from grey goods.

• 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.

Classification of Finishes • Textile Finishes are classified in several ways: According to function

Aesthetic Finishes

Functional Finishes

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

Fulling Mercerization Napping And Sueding 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

• According to the quality

Temporary

Permanent

Semi Permanent

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. • • • •

Calendering 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 Calendering • Buckram Finish

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According to type of machinery

Chemical Finishes

Mechanical Finishes

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

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. • • • •

Calendering Raising Sanforising Milling

• Routine finishes • Special finishes

Calendering • Calendering may be defined as the modification of the surface of a fabric 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 rollers can be either smooth or engraved to provide the appropriate finish to fabric.

• The rollers may be made of various material from hardened steel to elastic thermoplastic.

Objects of Calendering • To improve the fabric handle and to impart a smooth silky touch to the fabric • To compress the fabric and reduce its thickness • To reduce the air permeability by closing the threads • To increase the luster • To reduce the yarn slippage • To increase the opacity of the fabric • Surface patterning by embossing

Types of Calendering • • • • • •

Swissing or normal gloss or simple calendering Chintz or glazing or friction Calendering Cire Calendering Embossed Calendering Moiré Calendering Schrenier Calendering

Calendering machines

Types of calendering

Finishes enhancing appearance  Treatments enhancing appearance include such processes as             

napping and shearing, brushing, singeing, beetling, decating, tentering, calendering or pressing, moiréing, embossing, creping, glazing, polishing, and optical brightening.

Napping and shearing • Napping is a process that may be applied to woollens, cottons, spun silks, and spun rayons, including both woven and knitted types, to raise a velvety, soft surface. • The process involves passing the fabric over revolving cylinders covered with fine wires that lift the short, loose fibres, usually from the weft yarns, to the surface, forming a nap. The process, which increases warmth, is frequently applied to woollens and worsteds and also to blankets.

• Shearing cuts the raised nap to a uniform height and is used for the same purpose on pile fabrics. • Shearing machines operate much like rotary lawn mowers, and the amount of shearing depends upon the desired height of the nap or pile, with such fabrics as gabardine receiving very close shearing. • Shearing may also be applied to create stripes and other patterns by varying surface height

• Brushing • This process, applied to a wide variety of fabrics, is usually accomplished by bristle-covered rollers. • The process is used to remove loose threads and short fibre ends from smooth-surfaced fabrics and is also used to raise a nap on knits and woven fabrics. • Brushing is frequently applied to fabrics after shearing, removing the cut fibres that have fallen into the nap.

Singeing • Also called gassing, singeing is a process applied to both yarns and fabrics to produce an even surface by burning off projecting fibres, yarn ends, and fuzz. • This is accomplished by passing the fibre or yarn over a gas flame or heated copper plates at a speed sufficient to burn away the protruding material without scorching or burning the yarn or fabric. • Singeing is usually followed by passing the treated material over a wet surface to assure that any smoldering is halted.

• Singeing machines

• Beetling • Beetling is a process applied to linen fabrics and to cotton fabrics made to resemble linen to produce a hard, flat surface with high lustre and also to make texture less porous. • In this process, the fabric, dampened and wound around an iron cylinder, is passed through a machine in which it is pounded with heavy wooden mallets.

 Decating  Decating is a process applied to woollens and worsteds, manmade and blended fibre fabrics, and various types of knits.  It involves the application of heat and pressure to set or develop lustre and softer hand and to even the set and grain of certain fabrics. When applied to double knits it imparts crisp hand and reduces shrinkage.  In wet decating, which gives a subtle lustre, or bloom, fabric under tension is steamed by passing it over perforated cylinders

• Tentering, • These are final processes applied to set the warp and weft of woven fabrics at right angles to each other, and to stretch and set the fabric to its final dimensions. • Tentering stretches width under tension by the use of a tenter frame, consisting of chains fitted with pins or clips to hold the selvages of the fabric, and travelling on tracks. • As the fabric passes through the heated chamber, creases and wrinkles are removed, the weave is straightened, and the fabric is dried to its final size. • When the process is applied to wet wools it is called crabbing;

Tentering / stentering machines

 Creping  A crepe effect may be achieved by finishing. In one method, which is not permanent, the cloth is passed, in the presence of steam, between hot rollers filled with indentations producing waved and puckered areas.  In the more permanent caustic soda method, a caustic soda paste is rolled onto the fabric in a patterned form; or a resist paste may be applied to areas to remain unpuckered and the entire fabric then immersed in caustic soda.  The treated areas shrink, and the untreated areas pucker. If the pattern is applied in the form of stripes, the effect is called plissé; an allover design produces blister crepe.

Crepe effect

Raising • 1. Napping Using wire-covered rolls to "dig out" individual fiber ends to the surface • 2. Sueding Using abrasive-covered rolls (sandpaper, emery cloth, etc.) to produce shorter pile surface - does cause an apparent shade change. Special type of raised surface fabric is corduroy Sueding, sanding- creates softer hand of fabric.

suede

Shearing  Use of rotary blade(s) to trim raised surfaces (Surface pile or nap) to a uniform height.  Special types of blades and conveyer belts can produce pattern effects on the surface.  This reduces the tendency of the fabric surface to mat and also reduces the pilling tendency.  For pile fabrics, napped fabrics.

Raised Surface Finishes, add texture • 􀂄 Shearing- for pile fabrics, surface pile is cut to control the pattern and appearance. • Brushing• 􀂄 Embossed fabrics• 􀂄 Plisse’- puckered surfaces created by printing fabric with sodium hydroxide in stripes or designs. • 􀂄 Flocking • 􀂄 Glued on short fibers to create fuzzy surface • 􀂄 Napping/brushing – fiber ends raised by mechanical brushing • 􀂄 Fulled- wool fabrics are shrunk in a controlled manner, • 􀂄 Beetled• 􀂄 Sueding, sanding- creates softer hand of fabric. Emery paper or • some other mild abrasion to surface of fabric.

Mercerisation • Mercerisation is a treatment for cotton fabric and thread that gives fabric a lustrous appearance. The process is applied to materials like cotton or hemp. • The process was devised in 1844 by John Mercer of Great Harwood, Lancashire, England, who treated cotton fibres with sodium hydroxide. • Mercerisation alters the chemical structure of the cotton fibre. The structure of the fibre changes from alpha-cellulose to beta-cellulose. Mercerising results in the swelling of the cell wall of the cotton fibre. This causes increases in the surface area and reflectance, and gives the fiber a softer feel.

• The treatment of cellulosic fabric with caustic to improve dye-ability and handle. • The treatment of cellulosic textiles in yam or fabric form with a concentrated solution of caustic alkali whereby the fibres are swollen, the strength and dye affinity of the materials are increased, and the handle is modified. • A treatment of yarns or fabrics with caustic alkali, in which fibres are swollen and stretched to increase lustre in the finished product.

Parchmentizing • Treatment of cotton fabrics with sulfuric acid. • The fabric is transparent, sheer, stiff.

• Burn-out, effects created by dissolving part of the fibers in a blend fabric, leaving the second fiber in place.

Functional Finishes • All finishes that change a fabric's properties are applied chemically. • Property-changing functional finishes provide the added qualities desired for a particular fabric or they may be used to change an undesirable property to a more desirable one. • Many such finishes add more than one property to a fabric. The label may indicate which finishes have been applied to the fabric. • Examples of functional finishes that change the properties of fabric include:

• 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.

• Stabilization Finishes – • Sanforized indicates that a fabric has been treated so that it will shrink or stretch not more than 1 or 2%. Preshrunk fabrics have been preshrunk to a certain extent but still may shrink considerably

Pilling

 Anti-pilling finishes:  Pilling is an unpleasant phenomenon associated with spun yarn fabrics especially when they contain synthetics.  Synthetic fibers are more readily brought to the surface of fabric due to their smooth surface and circular cross section and due to their higher tensile strength and abrasion resistance, the pills formed take a long time to be abraded by wear.  With knit fabric, two more problems occur, viz., "picking" where the abrasion individual fibers work themselves out of yarn loops onto the surface when garment catches a pointed or rough object.

• Permanent Anti-static effects:

• Antistatic finish for synthetic textiles to avoid static charge build up & give a natural feel. • Anti-static effective chemicals are largely chemically inert and require Thermosol or heat treatment for fixing on polyester goods. • In general Thermsolable anti-static agents also have a good soil release action which is as permanent as the anti-static effect.

• Anti-static finishes may also be of polyamide type being curable at moderate temperatures

• Non-Slip finishes: • Synthetic warp and weft threads in loosely woven fabrics are particularly prone to slip because of their surface smoothness when the structure of fabric is disturbed and appearance is no loner attractive. • To avoid this attempts are made to give the filaments a rougher surface. • Silica-gel dispersions or silicic acid colloidal solutions are quite useful and they are used with advantage in combination with latex polymer or acrylates dispersions to get more permanent effect along with simultaneous improvement in resistance to pilling or snagging. • These polymer finishes are also capable of imparting a soft and smooth handle to synthetic fabric without imparting water repellency

 Fire Resistant finishes:  With synthetic fiber which melt on igniting by a flame, the molten moss is itself quite dangerous and a fire resistant treatment is desirable for certain end uses.  Polyester fabrics can be made flame resistant by treatment with an aqueous emulsion of xylene soluble 2,3dibromopropyl phosphate in a pad-cure sequence.  A semi-permanent effect can be produced by treating with a mixture of ammonium bromide and brominated phosphoric acid esters.

• Anti-microbial finishes: • With the increasing use synthetic fibers for carpets and other materials in public places, anti-microbial finishes have assumed importance. • Anti microbial finish Eco-friendly anti microbial finishing agent for cotton fabrics & Garments.Useful for eliminating bacterial growth due to sweat. • Products which are commonly applied are brominated phenols, quaternary ammonium compounds, organo-silver and tin compounds which can be applied as solutions or dispersions. • Mothproofing Finishes protect protein-containing fibres, such as wool, from being attacked by moths, carpet beetles and other insects.

• Waterproof Finishes -Aallows 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 (e.g. GORE-TEX, Bion II and Dicrylan). • 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, allweather coats, hats, capes, umbrellas and shower curtains (e.g. Cravaneete, Huydor-Pruf, Syl-mer, Scotchgard and Zepel).

• Stain and Soil Resistant Finishes - prevent soil and stains from being attracted to fabrics. • Such finishes may be resistant to oil-bourne 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. • Soil Release Finishes - These finishes attract water to the surface of fibres during cleaning and help remove soil.

• Flame-Retardant Finishes - In Canada, laws require that children's sleepwear and certain household furnishings meet certain standards for flammability resistance. • 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

Flame Resistant Finishes • Flame Resistant, the only performance required by law. Regulates the flammability of all people’s clothing.

• This removed extremely hazardous materials, such as things that will flash over quickly with only a small spark. • Clothing will still burn, however, the amount of flame and combustion is controlled.

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Flammability regulations cover children’s sleepwear, carpets, mattresses,upholstered furniture.

• Children’s sleepwear standard is a vertical flammability test, uses a gas flame to ignite the lower edge of the fabric.

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

Fragrance finish •

Done by Micro encapsulated silicone based aroma finishing agent.

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Microencapsulated skin moisturizers, vitamins and provitamins are applied in garments and known as cosmeto-textiles, designed for wear in contact with skin. These are claimed to promote a younger look, counteracting the effects of skin ageing, e.g. as a result of exposure to UV-radiation. There are also microencapsulated preparations for skin cooling. Home Textiles In other areas, household textiles such as curtains, sofas, cushions, sheets, as well as apparel items such as gloves, socks and ties may also be treated with microencapsulated fragrance and deodorizing finishes. The carpets can be finished with fragrances of different kinds and can be widely used in home textiles as well as automotive textiles.

• Sport Wears

As the ‘second skin’ of the human body, all types of textile are excellent media for transferring fragrance compounds, and are essential to people in sport according to their preference for them. The type of the fragrance necessary for sports wear may be orange, lemon which will keep them energized on the ground for longer period. Apparel The scents of lavender, rose, citrus or vanilla were encapsulated into fabrics, which proved a good way to meet important psychological and emotional needs, as well as those of a purely physical and sensorial nature. Thus the fabrics finished with above fragrances can be used in apparels, leisure wear, daily wears, party wears etc.

• Peach Finish: Subjecting the fabric (either cotton or its synthetic blends) to emery wheels, makes the surface velvet like. This is a special finish mostly used in garments.

Finishes for Synthetic fibers • Heat Setting: Heat setting of synthetic fabrics eliminates the internal tensions within the fiber generated during manufacture and the new state can be fixed by rapid cooling. • This heat setting fixes the fabrics in the relaxed state and thus avoids subsequent shrinkage or creasing of fabric. Presetting of goods make it possible to use higher temperature for setting without considering the sublimation properties of dyes and also has a favorable effect on dyeing behavior and running properties of goods.

• On the other hand, post setting can be combined with some other operations such as thermosol dyeing or optical brightening of polyester, post setting as a final finish is useful to get a high dimensional stability along with desired handle.

• Enzymatic finishes • Bio-polishing: This is a process to remove the protruding fibers of a fabric through the action an enzyme. This enzyme selectively acts on the protruding fibers and cease to work after finishing the work by a simple raise in temperature of the treatment bath.

Shrinkage Control Finishes • Some shrinkage expected in the first wash after weaving, the tensions created by being held on the loom are relaxed. • Sanforized, compressive shrinkage: Cottons are shrunk by compressing fabric between two blankets overfed over heated cylinders. • Sanfor-set, uses liquid ammonia to make the compressive shrinkage more permanent

• Heat setting, for Thermoplastics, heat fibers above their glass transition temperature- created a permanent shape • Shrinkage Control for Wool Remove the scales from the surface of the fiber Is a halogenation treatment that is fabric is treated with chlorine Or coat the scales with a polymer Coating is usually nylon

Wrinkle Resistant Finishes • Wrinkle recovery is dependent on the presence of cross links that hold adjacent molecules together and pull them back into shape when they are distorted • Other problems of DP finishes- stiffness, weakness, odor, soiling and affinity for soil, less moisture absorbent.