25 textile testing methods

TEXTILE TESTING METHODS INTRODUCTION Fabric testing is an important segment of the textile industry We can easily detect the faults of machinery and materials during test of textiles Textile standards: Standard is a prescribed required level of performance of material These standards are: • NFPA: National Fire Protection Association • ANSI: American National Standard Institute • ISO: International organization for COTTON Co tto n fibe r is a single elongated cell Under a microscope, cotton fiber looks like flat, spirally twisted ribbon-like tube with rough granular surface Mercerized cotton does not have natural twist The finishing process makes them swollen, straight, smooth and round with a shining surface Microscopic view of cotton WOOL Wo o l fib e r has irregular, roughly cylindrical, multi cellular structure with tapered ends Under a microscope, three basic layers are showne p id e rm is (outer layer), c o rte x (middle layer) and m e d ulla (inner layer) Medulla is seen only in coarse and medium wool fibers and that too under a highly powerful MICROSCOPIC VIEW OF WOOL LINEN Line n fib e r, under a microscope, looks like having multiple sided cylindrical filaments with fine pointed edges The filaments show nodes at intervals It, in fact, looks like a bamboo stick having joints that results into a little unevenness Microscopic view of linen/flax SILK • S ilk fib e rs are straight and smooth • Raw silk fiber, composed of two filaments, has elliptical shape under the microscope • The two fine and lustrous filaments are shown clearly looking like transparent rods with triangular shape • Wild silk or tussah fiber has different appearance than the cultivated silk It is flattened, coarse, thick and broader fiber having fine, wavy lines all across its surface whereas cultivated silk is narrower fiber with no marks on MICROSCOPIC VIEW OF SILK POLYESTER • Polyester (aka Te ry le ne ) is a category of polymers which contain the ester functional group in their main chain • Generally, polyester fibers are smooth and straight and the cross-section is round • With various finishing processes, its appearance changes in context of texture and luster MICROSCOPIC VIEW OF POLYESTER NYLON The basic microscopic appearance is generally fine, round, smooth, and translucent Sometimes it has shiny appearance If it looks dull, it will also be dotted under the microscope.  It is also produced in multilobal cross-sectional types MICROSCOPIC VIEW OF NYLON PHYSICAL TESTS BREAKING STRENGTH TEARING STRENGTH BURSTING STRENGTH PILLING PROPENSITY AIR PERMEABILITY ABRASION RESISTANCE BREAKING STRENGTH • • Bre aking s tre ng th is the force required to break a fabric when it is under tension (being pulled) Bre aking lo ng atio n is the increase in length that has occurred when the fabrics breaks IMPORTANT CONSIDERATIONS BEFORE WASHING • The washing temperature should have a great affect on colors Often the dye is loosened from fabrics by the action of hot water • Additions to bath Bleaching and sodium carbonate should be included to intensify the washing action • Time is important Articles from which dye runs should be washed without soaking and for less time so that less amount of color runs out IMPORTANT CONSIDERATIONS BEFORE WASHING • Mechanical action Mechanical action subjected to laundering should also be included in washing test • Proportion of liquid The proportion of liquid to the amount of material washed is important because if volume of liquid is too high, the material would just float without the squeezing Whereas in smaller amount there would be twisting action COLORFASTNESS TO CROCKING • Crocking is the transference of color by rubbing from one colored textile material to another • Similarly, printed fabrics often will crock more easily than dyed fabrics because in printed fabrics the dye is on the surface than inside the fabric • Dark shades are more likely to crock than light colors because there is more dye in dark colors than light ones • Wet fabrics will crock more easily than dry ones because the moisture present assists in removing the dye COLORFASTNESS TO CROCKING • The arm is rotated back & forth causing the white crock test cloth to rub against the specimen • The cloth is removed and evaluated on a scale of to 1.(class 5:negligible or no crocking; class : large amount of crocking) The device used is crock meter COLORFASTNESS TO CROCKING • The arm is rotated back & forth causing the white crock test cloth to rub against the specimen • The cloth is removed and evaluated on a scale of to 1.(class 5:negligible or no crocking; class : large amount of crocking) Colorfastness to frosting •Frosting is a localized color change produced by a relatively severe, localized flat abrasion action Eg back pocket of a pair of trousers •Fabrics with poor dye penetration will fade quickly from abrasion as on the surface will wear, leaving a very little color •Blended fabric can change colors if each fiber has different abrasion resistance •Eg in a dark grey fabric, the black cotton will abrade more quickly than a white polyester fabric, developing a light grey color •The device used is a surface Abrader Colorfastness to perspiration •Perspiration may change the color of a fabric •Three things may take place : color change of the dyed fabric Loosening and uneven repositioning of color on colored fabric Staining of material next to the colored fabric • • • • Perspiration maybe slightly acidic but through bacterial action, it becomes alkaline The dye may get affected by both The device used is the perspiration tester a slightly acid solution on one cloth & alkaline on another is used Both specimens are tested The one with the most color change is used to represent the fabric and its class rating is used as a result Colorfastness to dry cleaning •Color may change due to dry cleaning too •This test indicates what will happen to the color of textile materials after repeated commercial dry cleaning •Perchlorethylene is used in the test: •Commonly used dry cleaning solvents •It is slightly more severe in solvent action •A color that may get affected by perchlorethylene will not get affected by Stoddard solvent (petroleum base) •Device used for this test is the launderometer •Dry cleaning solvent instead of water is used as liquid Colorfastness to burnt gas fumes •Lastly, color changes due to the presence of nitrous oxide in the atmosphere •Acetate is the most susceptible to this gas •When disperse dye is combined with acetate , severe color changes take place.eg blue which changes to purple •Solution dyeing & inhibitors can be used to reduce or eliminate color fading •The device used to perform the test is called gas fading chamber •The source of burnt gas fumes is a Bunsen burner placed at the bottom of the instrument Chemical test •In these types of tests , chemicals are used as a part of the test procedure •the specimen is dissolved in the chemical to check its solubility •The test include : •Colorfastness •Fiber identification using the solubility test Chemical solubility test COTTON & FLAX: They can be differentiated by observing their longitudinal appearance with a microscope SOLVENTS CONCENTRATION TEMPERATURE MINUTES FIBER SULPHURIC ACID 70% 38*C 20 COTTON SULPHURIC ACID 70% 38*C 20 FLAX SILK & WOOL: Differentiate visually SOLVENTS CONCENTRATION TEMPERATURE MINUTES FIBER SODIUM 5.25% HYPOCHLORITE 20*C 20 WOOL SODIUM 5.25 % HYPOCHLORITE 20*C 20 SILK Polyester: SOLVENTS CONCENTRATION TEMPERATURE MINUTES FIBER META-CRESOL 100% 139*C POLYESTER Acetate : SOLVENTS CONCENTRATION TEMPERATURE MINUTES FIBER ACETIC ACID 100% 20*C ACETATE Rayon: SOLVENT CONCENTRATION TEMPERATURE HYDROCHLORIC 38% ACID 24*C MINUTES FIBER RAYON Nylon: SOLVENTS CONCENTRATION TEMPERATURE MINUTES FIBER META-CRESOL 100% NYLON 139*C Spandex: SOLVENT CONCENTRATION TEMPERATURE MINUTES FIBER DIMETHYL FORMAMIDE 100% 90*C 10 LYCRA/ SPANDEX [...]... tear strength • Tearing strength is e xp re s s e d e ithe r in p o und s o r g ram s BURSTING STRENGTH Burs ting s tre ng th is the amount of pressure required to rupture a fabric • In this test, the testing force is applied radially and not in one direction as in breaking or tearing strength tests • Fabrics like knits, felt, non woven, lace and netting are usually tested in this manner because these... as a result AIR PERMEABILITY Air p e rm e ab ility is the rate of air flow through a material under a differential pressure between two fabric surfaces This property is important for a wide range of textile applications With some products like curtains high air permeability is required and for other products like parachutes and gas filters air permeability required is very less Air permeability is... physical wear appear Nylon is extremely high in abrasion resistance so it is used widely in action outer whereas Acetate has poor abrasion resistance so it does not last long when used for lining in CHEMICAL TESTING • COLORFAS TNES S PROPERTIES • CHEMICAL S OLUBILITY TES T COLORFASTNESS PROPERTIES • Used to determine the resistance of dyed or printed fabrics to color change under various conditions • There... material would just float without the squeezing Whereas in smaller amount there would be twisting action COLORFASTNESS TO CROCKING • Crocking is the transference of color by rubbing from one colored textile material to another • Similarly, printed fabrics often will crock more easily than dyed fabrics because in printed fabrics the dye is on the surface than inside the fabric • Dark shades are more... is used to represent the fabric and its class rating is used as a result Colorfastness to dry cleaning •Color may change due to dry cleaning too •This test indicates what will happen to the color of textile materials after repeated commercial dry cleaning •Perchlorethylene is used in the test: •Commonly used dry cleaning solvents •It is slightly more severe in solvent action •A color that may get ...INTRODUCTION Fabric testing is an important segment of the textile industry We can easily detect the faults of machinery and materials during test of textiles Textile standards: Standard... Differentiate visually SOLVENTS CONCENTRATION TEMPERATURE MINUTES FIBER SODIUM 5 .25% HYPOCHLORITE 20*C 20 WOOL SODIUM 5 .25 % HYPOCHLORITE 20*C 20 SILK Polyester: SOLVENTS CONCENTRATION TEMPERATURE... differential pressure between two fabric surfaces This property is important for a wide range of textile applications With some products like curtains high air permeability is required and for