Introduction of Pressing Fastness Test | Color Fastness to Pressing

Color Fastness to Pressing:
Pressing fastness test of dyed and printed textile products is performed to determine of resistance of textiles to ironing and to processing on cylinders. Different tests are performed according to when the textile is dry, when it is wet, and when it is damp. 

Purpose and Scope:
This method is used for determining the resistance of the colour of textile of all kinds and in all forms to ironing and processing on hot cylinders. Tests are given for hot pressing when the textiles are wet, when it is damp, and when it is dry.

Apparatus and Reagent  

• Hand iron of proper weight to give a pressure of approximately 30g/sq.cm at the temperature indicated in the following ;

1. Cotton & Linen 190-200C˚
2. Wool, Silk & Viscose 140-160C˚
3. Cellulose acetate & Polyamide 115-120C˚

• White bleached cotton cloth weighting approximately 125g/sq.meter. Five pieces not less than 14×4 cm are required. 
• Gray scale by assessing change in colour and staining.(ISO scale)  
• The size of the specimen is 10×4cm

Working Procedure
Specimen preparation
Specimen of materials, which has been subjected to any heat or drying treatment, must be allowed to condition at 65% RH, temp. 20±2C˚, before they tested.

Dry Pressing
Place the specimen on the piece of dry cotton cloth on a smooth horizontal surface. Place the iron on the specimen and leave it for 15 Sec.

Damp Pressing: 

The adjacent fabric in dimensions of 100 mm x 40 mm is immersed into the water and, squeezed as 100% pick up. Dry specimen is placed onto the undyed cotton fabric on the filler and, the wet adjacent fabric is placed onto them. The top layer of the device is pulled down and, dry specimen is pressed for 15 seconds at the determined temperature. The change in color of the specimen is evaluated in two different ways according to grey scale.

a) Soon after the end of the test
b) After conditioning for 4 hours under standard atmospheric circumstances.
The staining to undyed fabrics is evaluated by grey scale.

Wet Pressing
Soak the specimen and cotton cloth in distilled water and squeeze or extract them to contain their own weight of water. Place the wet specimen on a piece of the dry cotton cloth and place the wet cotton cloth on the specimen, press by moving the iron to and fro over the wet cloth (without additional pressure) for 15 sec.

Assessment
Assess the change in colour of the specimen with appropriate grey scale.

Standard
Dry Pressing 4
Wet Pressing 3-4 

Introduction of Perspiration Test | Color Fastness to Perspiration

The color fastness to perspiration (acid and alkaline) shall be at least level 3-4 (color change and staining). This criterion does not apply to white products, to products that are neither dyed nor printed, to furniture fabrics, curtains or similar textiles intended for interior decoration. A level of 3 is nevertheless allowed when fabrics are both light colored (standard depth

Color Fastness to Perspiration
The garments a\which come into contact with the body where perspiration is heavy may suffer serious local discoloration. This test is intended to determine the resistance of color of dyed textile to the action of acidic and alkaline perspiration. Before knowing about the Color Fastness to perspiration you must have to know about Color Fastness to Wash and Color Fastness to Rubbing.

Perspirometer

Well, in today’s class you will know about the perspiration matters which affects on Color fastness.

Purpose and Scope
This method is used to determine the resistance of the colour of textile of all kinds and in all forms to perspiration.

Equipment For Fastness Measurement

1. Perspiration tester
2. Oven, Maintained at 37+-2 Degree centigrade
3. Multifiber test fabric
4. Grey scale
5. Color matching chamber
6. Acidic and Alkaline solution
7. Glass or Acrylic plat
8. Weight.

Reagent for Perspiration Test

1. Solution freshly prepared, containing 0.5g 1-histidine mono-hydrochloride mono-hydrate, 5g sodium chloride, and 2.5g disodium hydrogen ortho phosphate per litre brought to PH 8.0 with 0.1N sodium hydroxide.
2. Solution freshly prepared, containing 0.5g 1-histidine mono-hydrochloride mono-hydrate, 5g sodium chloride, and 2.2g sodium dihydrogen ortho phosphate per litre brought to PH 5.5 with 0.1N sodium hydroxide.
3. Two undyed cloths for each specimen each 6×6cm of the same kind of fibre as the sample. Place the specimen between the two pieces of white cloth and sew along one side to form a composite sample.

Working Procedure :
Thoroughly wet one composite sample in a solution of PH8.0 at the liquor ratio of 20:1 and allow it to remain in this solution at room temperature for 30min. pour off the solution and place the composite sample between two glasses plates measuring about 7.5×6.5cm under a force of about 4.5kg.

1. Treat the other sample in the same way but with the solution at PH 5.5.
2. Place the apparatus containing the samples in the oven for 4 hour at 37±2C˚
3. Separate the sample from the white cloth and dry them apart in air at the temperature not exceeding 60C˚
4. Assess the change in colour of the specimen and the staining of the white cloth with the greigh scale.

What is Pilling Formation on Fabric? | Pilling Resistance Test |Working Procedure of Pilling Resistance Test

Pilling
Pilling is a condition that arises in wear due to the formation of little ‘pills’ of entangled fibre clinging to the fabric surface giving it an unsightly appearance. Pills are formed by a rubbing action on loose fibres which are present on the fabric surface. Pilling was originally a fault found mainly in knitted woollen goods made from soft twisted yarns. The introduction of man-made fibres into clothing has aggravated its seriousness. The explanation for this is that these fibres are stronger than wool so that the pills remain attached to the fabric surface rather than breaking away as would be the case with wool. Figure 7.3 shows a pill on a cotton/polyester fabric.

The initial effect of abrasion on the surface of a fabric is the formation of fuzz as the result of two processes, the brushing up of free fibre ends not enclosed within the yarn structure and the conversion of fibre loops into free fibre ends by the pulling out of one of the two ends of the loop. Gintis and Mead consider that the fuzz formation must reach a critical height, which is dependent on fibre characteristics, before pill formation can occur.

Pilling Resistance Test:
Purpose and Scope:
This method is intended for the determination of the resistance of textiles of all kinds in all forms to the action of an applied resistive force. This causes pilling in the tested fabrics

Apparatus:
· Pilling tester
· Metal plates 4 inch diameter and 1 inch thick
· Standard for assessing the pilling grade

Working Procedure:
A piece of fabric measuring 10×10 inch is sewn to a firm fit when placed round a rubber tube. The out end of the fabrics is covered by cellophane tape and metal plates are placed on the tester .Run the tester for 300 cycles. Remove the sample and compare the sample with standard scale. 

Standard
Pilling Standard:              3-4 gray scale matching 

Biomedical Textiles | Biomedical Textile Products | Application ofBiomedical Textiles

 Introduction of Biomedical Textile

Biomedical textiles are fibrous structures designed for use in specific biological environments, where their performance depends on biocompatibility with cells and biological tissue or fluids.It is also branch of technical textile.Biomedical textiles are textile products and constructions, for medical and biological applications. It is related to medical textile. They are used for first aid, clinical or hygienic purposes. This type of textiles are manufactured from a wide range of processes. Extruded polymers can be further processed or used as filaments or tapes in dental floss and toothbrushes. Braided textiles are used for sutures and to replace damaged tendons and ligaments. Woven and knitted materials are used extensively in bandages, vascular grafts and hernia meshes. A specialised area of medical textiles is the extrusion of hollow fibre membranes used in extracorporeal devices. Non-wovens are primarily made from synthetic fibres and uses include wound dressings, hygiene products and protective clothing.

The design of a biomedical textile is driven by its end function. The main factors include:

Biodegradable Textiles : 

The textile needs to fulfil the purpose for which it was designed, for example swabs require an absorbent textile, sutures may require a biodegradable textile, while hospital bedding should be comfortable and durable.

Biocompatibility: 

This refers to the reaction of the textile with blood and tissue in the body. An implantable device has more potential for reaction than an external device and is, therefore, subject to tighter regulations. For example an artificial ligament is permanent and is able to react with blood cells and the surrounding tissue, compared to an external bandage that is temporary and only contacts the outer skin tissue.

Cost: 

This will depend on the raw materials, manufacturing process and product end-use; surgeons’ gowns and swabs should have a low production cost while vascular grafts and artificial skin will have a relatively high production cost.

Product approval: 

Each country has its own regulations and standards for medical textiles. However the European Union has introduced Community Legislation to govern medical devices. The three directives are: Active Implantable Medical Devices, Medical Devices Directive and In-Vitro Diagnostic Medical Devices.

Biomedical Textile Products
Biomedical textiles are textile products and constructions, for medical and biological applications. They are used for first aid, clinical or hygienic purposes. Examples of their application are: 

Protective and healthcare textiles
Surgeons’ wear, Operating drapes and Staff uniforms, etc. 

External devices
Wound dressings, bandages, pressure garments, prosthetic socks, etc. 

Implantable materials
Sutures, vascular grafts, artificial ligaments, etc. 

Hygiene products
Incontinence pads, nappies, tampons, sanitary towels, etc. 

Extracorporeal devices
Artificial liver, artificial kidney, artificial lung, etc.

Application of Biomedical Textiles
Since the 1960s, biomedical textiles have been used in cardiovascular medical devices, such as vascular grafts and heart valve sewing cuffs. However, the current wave of innovation is looking far beyond traditional materials and textile structures to enhance capabilities and performance in the repair of damaged or diseased cardiovascular tissue. In fact, the advent of new fabrics and geometries with greater variability of properties and performance characteristics, including the combination of resorbable and nonresorbable polymers, has enabled design developments previously unimagined.

Some uses are given below:
Protective and healthcare textiles: surgeons’ wear, operating drapes and staff uniforms, etc.
External devices: wound dressings, bandages, pressure garments, prosthetic socks, etc.
Implantable materials: sutures, vascular grafts, artificial ligaments, etc.
Hygiene products: incontinence pads, nappies, tampons, sanitary towels, etc.
Extracorporeal devices: artificial liver, artificial kidney, artificial lung, etc.

Introduction of Textile Finishing Process | Mechanical Finishing inTextile | Chemical Finishing in Textile | Enzyme Finishing

Textile Finishing

Textile Finishing is a process used in manufacturing of fiber, fabric, or clothing. In order to impart the required functional properties to the fiber or fabric, it is customary to subject the material to different type of physical and chemical treatments. For example wash and wear finish for a cotton fabric is necessary to make it crease free or wrinkle free. In a similar way, mercerising, singeing, flame retardant, water repellent, water proof, antistatic finish, peach finish etc are some of the important finishes applied to textile fabric.

Broadly it can be classified into following classes,which are used individually or in combination with each other. (other terms are also used such as wet finishing, dry finishing, durable finishes and non durable finishes)

1.Mechanical Finishing:

Involving the application of physical principles such as friction, temperature, pressure, tension and many others.

Calendering
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 interlacings 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 calendering, 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 planeness of surface in turn improves the glaze of the fabric. The calender machines may have several rollers, some of which can be heated and varied in speed, so that in addition to pressure a polishing action can be exerted to increase lustre.

Compacting
Durable finish imparted on man-made fibres and knitted fabrics by employing heat and pressure to shrink them to produce a crêpey and bulky texture.

Embossing
This particular type of calendering process allows engraving a simple pattern on the fabric.To produce a pattern in relief by passing fabric through a calendar in which a heated metal bowl engraved with the pattern works against a relatively soft bowl, built up of compressed paper or cotton on a metal centre.

Sueding
This process is carried out by means of a roller coated with abrasive material. The fabric has a much softer hand and an improved insulating effect thanks to the fibre end pulled out of the fabric surface.

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 interlacings of the warp and the filling. Napped fabrics include blankets, flannel, unfinished worsted, and several types of coatings and some dress goods. Other names for napping are Gigging, Genapping, Teaseled, Raised.

Wool Glazing
This is done on a special machine, which is used to perform functional finishing on wool fabrics after raising.

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

Decating
Also called Decatizing. A finishing process applied to fabrics to set the material, enhance lustre and improve the hand.Fabric wound onto a perforated roller is immersed in hot water or has steam blown through it.

Steaming and Heat setting
It is done by using high temperatures to stabilize fabrics containing polyester, nylon, or triacetate but not effective on cotton or rayon.it may be performed in fabric form or garment form it may cause shade variation from side-to-side if done prior to dyeing; may change the shade if done after dyeing

Sanforizing or Pre Shrinking
Sanforizing is a process where by 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 vapour.

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

2.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.

Soil Release Finishes

These finishes attract water to the surface of fibres during cleaning and help remove soil.

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.
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.

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. Other terms that can be used include anti-slip, non-shift and slip-proofing finishes.

Stain and Soil Resistant Finishes
Prevent soil and stains from being attracted to fabrics. Such finishes may be resistant to oil-boure 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

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 are fabric softeners.

Anti Mildew
In certain ambient (humidity and heat) conditions, cellulose can be permanently damaged. This damage can be due to depolymerisation of the cellulose or to the fact that certain microoganisms (mildews) feed off it. The situation is worsened, during long storage periods, by the presence of starch finishing agents.This damage can be prevented by the use of antiseptics, bacteria controlling products containing quaternary ammonium salts, and phenol derivatives. Dyestuffs containing heavy metals can also act as antiseptics. Permanent modification of the fibre (cyanoethylation) is another possibility.

Mothproofing Finishes
Protect protein-containing fibres, such as wool, from being attacked by moths, carpet beetles and other insects.

Antibacterial Finish
The inherent properties of textile fibres provide room for the growth of micro-organisms. The structure and chemical process may induce the growth, but it is the humid and warm environment that aggravates the problem further. Antimicrobial finish is applied to textile materials with a view to protect the wearer and textile substrate itself.

Antimicrobial finish provides the various benefits of controlling the infestation by microbes, protect textiles from staining, discoloration, and quality deterioration and prevents the odor formation.Anti-microbial agents can be applied to the textile substrates by exhaust, pad-dry-cure, coating, spray and foam techniques. The application of the finish is now extended to textiles used for outdoor, healthcare sector, sports and leisure.
UV ProtectionFabric treated with UV absorbers ensures that the clothes deflect the harmful ultraviolet rays of the sun, reducing a person’s UVR exposure and protecting the skin from potential damage. The extent of skin protection required by different types of human skin depends on UV radiation intensity and distribution with reference togeographical location, time of day, and season. This protection is expressed as SPF (Sun Protection Factor), higher the SPF value better is the protection against UV radiation.

Colorfastness Improving Finish
Colour fastness is the resistance of a material to change in any of its colour characteristics, to the transfer of its colourants to adjacent materials or both. Fading means that the colour changes and lightens. Bleeding is the transfer of colour to a secondary, accompanying fibre material. This is often expressed as soiling or staining meaning that the accompanying material gets soiled or stained.

The physical and chemical principles involved in the performance of the fastnessnimproving finishes concern either the interaction with the dyestuff or with the fibre or both.

The finishes are applied to
a.Improve the colorfastness to washing
b.Improve the colorfastness to crocking
c.Improve the colorfastness to light
d.Improve the colorfastness to weathering
e.Improve the colorfastness to chemicals washes such as mild bleaching , dry cleaning and commercial washing.

Plasma finish
Plasma treatment is a surface modifying process, where a gas (air, oxygen, nitrogen, argon,carbon dioxide and so on), injected inside a reactor at a pressure of approximately 0.5 mbar, is ionised by the presence of two electrodes between which is a high-frequency electric field. The need to create the vacuum is justified by the necessity to obtain a so-called cold plasma with a temperature no higher than 80 °C. This, with the same energy content that can be reached at atmospheric pressure at a temperature of some thousands of degrees C, permits the treatment of fabrics even with a low melting point such as polypropylene and polyethylene, without causing any form of damage.The fabric, sliding through the electrodes, is subject to a true bombardment from the elements that constitute the plasma (ions, electrons, UV radiation and so on) and which come from the decomposition of gas and contain a very high level of kinetic energy. The surface of the fabric exposed to the action of the plasma is modified, both physically (roughness), as well as chemically, to remove organic particles still present and to prepare for the successive introduction of free radicals and new chemical groups inside the molecular chain on the surface of the material. The mechanical properties remain, on the other hand, unaltered, as the treatment is limited to the first molecular layers.

3.Enzyme Finishing
Bio polishing, also called bio-finishing, is a finishing process applied to cellulosic textiles that produces permanent effects by the use of enzymes. Bio-finishing removes protruding fibres and slubs from fabrics, significantly reduces pilling, softens fabric hand and provides a smooth fabric appearance, especially forknitwear and as a pretreatment for printing.

Sewing Thread Finishing
Apart from many of the above said finishes which can be applied to sewing threads also, A variety of finishes are used to improve the sewability of sewing thread,for example

1. Lubricants reduce friction and improve the lubricity of the thread.Lubricity refers to the frictional characteristics of thread as it passes through the sewing machine and into the seam. Good lubricity characteristics will minimize thread breakage and enhance sewability.
    
2. Glazing increases strength and abrasion resistance.Glaze Finish refers to a finish put on 100% cotton threads or cotton-polyester core spun thread made from starches, waxes or other additives. This coating is then brushed to give the thread a smooth surface. A glaze finish protects the thread during sewing giving better ply security and abrasion resistance.
    
3. Bonding to increase strength and surface smoothness. Bonded Finish refers to a finish applied to continuous filament nylon and polyester threads which coats the fibers, giving the thread better ply security and abrasion resistance. 

What is Fastness? | Color Fastness Scales | Colour Change Grey Scales |Degree of Staining Grey Scales

Fastness:

Fastness is the resistance of a textile material to specific chemical agencies. Poor colour fastness in textile products is a major source of customer complaint. The fastness of a colour can vary with the type of dye, the particular shade used, the depth of shade and how well the dyeing process has been carried out. Dyes can also behave differently when in contact with different agents, for instance dyes which may be fast to dry-cleaning may not be fast to washing in water. It is therefore important to test any dyed or printed product for the fastness of the colours that have been used in its decoration.

There are a number of agencies that the coloured item may encounter during its lifetime which can cause the colour either to fade or to bleed onto an adjacent uncoloured or light coloured item. These factors vary with the end use for which the product is intended. For instance carpets and upholstery are cleaned in a different way from bed linen and clothing and therefore come into contact with different materials. The agencies that affect coloured materials include light, washing, dry-cleaning, water, perspiration and ironing. There are a large number of colour fastness tests in existence which deal with these agencies and a full list will be found in the British Standard. A further group of tests is connected to processes in manufacturing that the coloured material may undergo after dyeing but before completion of the fabric, processes such as decatising or milling. Despite the fact that the list of colour fastness tests is very long, most of them are conducted along similar lines so that the main differences among the tests are in the agents to which the material is exposed.

Colour fastness is usually assessed separately with respect to:
1 changes in the colour of the specimen being tested, that is colour fading;
2 staining of undyed material which is in contact with the specimen during the test, that is bleeding of colour.

In order to give a more objective result a numerical assessment of each of these effects is made by comparing the changes with two sets of standard grey scales, one for colour change and the other for staining.

1. Colour Change Grey Scales

These scales consist of five pairs of grey coloured material numbered from 1 to 5. Number 5 has two identical greys, number 1 grey scale shows the greatest contrast, and numbers 2, 3 and 4 have intermediate contrasts. After appropriate treatment the specimen is compared with the original untreated material and any loss in colour is graded with reference to the grey scale. When there is no change in the colour of a test specimen it would be classified as ‘5’; if there is a change it is then classified with the number of the scale that shows the same contrast as that between the treated and untreated specimens. 

 

Fig: Gray Scale

2 .Degree of Staining Grey Scales

A different set of grey scales is used for measuring staining. Fastness rating 5 is shown by two identical white samples (that is no staining) and rating 1 shows a white and a grey sample. The other numbers show geometrical steps of contrast between white and a series of greys. A piece of untreated, unstained, undyed cloth is compared with the treated sample that has been in contact with the test specimen during the staining test and a numerical assessment of staining is given. A rating of 5 means that there is no difference between the treated and untreated material. If the result is in between any two of the contrasts on the scale, a rating of, for example, 3-4 is given. Sets of grey scales, examples of which are shown in Fig: can be supplied by the British Standards Institution.