ASSIGNMENTOF

TEXTILE TESTING AND

QUALITY CONTROL

Topic: 1. IDENTIFICATION OF FIBERS2. COLOR FASTNESS TO WASHING3. COLOR FSATNESS TO LIGHT4. COLOR FASTNESS TO RUBBING

Name: Syed Asim NajamClass: BS-T VIII

Submitted to: Dr. Raees

BURNING TESTTo recognize the composition of fabrics by the burning test ,the sample of fiber, yarn of fabric should be moved slowly towards a small flame and the reaction to heat carefully observed .One end of the sample should be put directly into flame to determine its burning rate and characteristics. The burning odour should be noted and the characteristics of the ash such as amount, form, hardness and color should be examined.IDENTIFICATION OF FIBRES THROUGH BURNING TEST

Cotton When ignited it burns with a steady flame and smells like burning leaves. The ash left is easily crumbled. Small samples of burning cotton can be blown out as you would a candle.Nylon Nylon melts and then burns rapidly if the flame remains on the melted fibre. If you can keep the flame on the melting nylon, it smells like burning plastic.Polyester Polyester melts and burns at the same time, the melting, burning ash can bond quickly to any surface it drips on including skin. The smoke from polyester is black with a sweetish smell. The extinguished ash is hard.Rayon It is a regenerated cellulose fibre which is almost pure cellulose. Rayon burns rapidly and leaves only a slight ash. The burning smell is close to burning leaves.Silk It is a protein fibre and usually burns readily, not necessarily with a steady flame, and smells like burning hair. The ash is easily crumbled. Silk samples are not as easily extinguished as cotton or linen.Wool It is also a protein fibre but is harder to ignite than silk as the individual "hair" fibres are shorter than silk and the weave of the fabrics is generally looser than with silk. The flame is steady but more difficult to keep burning. The smell of burning wool is like burning hair.

TECHNICAL TESTSThere are certain technical tests performed for identifying various fibers. These tests require high technology laboratory equipment and are much more reliable than the non technical fibre tests. Technical tests require high skilled personnel and technical know how of handling chemicals and their accurate analysis. These tests are very valuable for those fabrics that are a blend of different yarns and also have certain special properties including flame retardance etc.

TYPES OF TECHNICAL TEST Microscopic test Chemical test

MICROSCOPIC TEST Microscopic test is a technical test that involves identifying the fabric with the help of a microscope with a magnification of minimum 100 powers. The test can easily distinguish between fibers. The test identifies the natural fibers more easily as compared to man made ones. Synthetic fibers are very similar in appearance and the increase in the number of varieties makes it a little tough to distinguish the fibers even under a microscope.

MICROSCOPIC TEST:COTTON:It is a single elongated cell. Under the microscope, it resembles a collapsed, spirally twisted tube with a rough surface. The thin cell wall of the fiber has from 200 to 400 convolutions per inch.

WOOL:Under the microscope , wool’s cross section shows three layers- epidermis, cortex and the medulla.

SILK:It appears somewhat elliptical and triangular in cross section when we see under the microscope. It is composed of fibroin, consisting of two filaments, called brin which is held together by sericin.

RAYONS:Rayon fibers have a glasslike luster under the microscope and appear to have a uniform diameter when viewed longitudinally.

NYLON:The basic microscopic appearance is generally fine, round, smooth, and translucent. It is also produced in multilobal cross-sectional types.

Nylon

POLYESTERS:Generally, polyester fibers are smooth and straight and the cross-section is round. This general characteristics may be altered to achieve certain characteristics.

CHEMICAL TESTSChemical tests are another technical means of identifying fibers. But chemical tests are not intended for the general consumers. Different types of chemical tests are undertaken to establish the identity of the fibers used. These tests give accurate and precise analysis. The tests are conducted in research laboratories.TYPES OF CHEMICAL TESTSolvent Test:The test involves treating the fibres in certain solvents for identifying them. The technical test is becoming difficult to conduct as most of the manufactured fibres and their blends are chemically similar. There is no individual chemical or solvent test for separating or identifying the fibres in combinations.Distinguishing animal from vegetablefibres with an acidAs strong alkali destroy animal substances, a 5% of soda lye solution in water can be used to eliminate wool and silk fibers from a sample that contains a mixture of fiber. The vegetable fibres will not be affected by this solution.Distinguishing vegetable from animal fibres with an acidAs dilute acid destroy vegetable fibers, a 2% sulphuric acid solution can be used. A drop of solution is placed on the sample, which is then pressed with a hot iron. The spotted area will become charred if the sample is cotton linen or rayon.DISTINGUISHING SILK FROM WOOL:The use of concentrated cold hydrochloric acid will dissolve the silk and the wool fiber swells.DISTINGUISHING NYLON FROM OTHER FIBRES:If the fabric is thought to contain nylon, the fabric may be immersed in a boiling solution of sodium hydroxide. The nylon is insoluble in such a solution.DISTINGUISHING POLYESTERS FROM OTHER FIBRES:Polyester is soluble in hot meta cresol; however, unlike acetate it is not soluble in acetone, and unlike nylon it is not soluble in concentrated formic acid.DISTINGUISHING GLASS FIBERS FROM OTHER FIBRES:There are two specific solvents for quick identification of glass fibers, they are hydrofluoric acid and hot phosphoric acid.

COLOR FASTNESS TO WASHING:

The test specimen is stitched with one pieces of test fabrics, then put into washing liquid. Rotated under a certain temperature for a certain time, the combination of specimen and test fabrics is wash with distilled water and then dried. Assess the color change of specimen and the staining of test fabrics with gray scale.

ProcedurePerform a test color fastness to washing using wash wheel. The sizes of specimens required for the various tests are 10x4 cm. There are various types of test fabrics which are stitched on specimens. Different standard provides different test fabrics. Put the test combination of test specimen and test fabrics in the canisters. Test one combination in each canister.Fill wash liquor in the canisters. Put a certain amount of steel balls in the canisters. Mount the canisters in the washer.There is a canister frame in the washer. Insert the canisters in the special slots on the frame and fix them. Fill water into washer (water use to heat the canister). Generally, the washer should preheat the canisters at least 2min. And then rotate the canister frame for 45min at the speed of 40 RPM. Wash the combinations in a certain way and precondition them after getting them out of the canisters. Cut the test fabrics off the specimens. Assess the color change of the specimen by comparing it with Change in Color Gray Scale and evaluate the staining of the test fabrics by comparing it with Staining Gray Scale.

Wash Test Conditions:

COLORFASTNESS TO RUBBING: For determining the color fastness to rubbing a suitable device (crock meter) with a rubbing finger, comprising a cylinder of 1.6 cm diameter moving to and from in a straight line along a 10.0 cm track on the specimen with a downward force of 9N should be used. Crockmeter is motorized is an advanced crockmeter, which is operated by geared motor. It consists of the main unit having oscillating arm with a finger, which rubs over the test specimen under a specified load over the specimen.

Preparation of the Specimen

If the textile to be tested is a fabric, two pieces, each not less than 14 cm x 5 cm for dry rubbing and two pieces for wet rubbing should be drawn from the sample.

The test specimen should be fixed on the rubbing device by means of clamps such that the long direction of the specimen follows track of the device.

In case of multicoloured textiles, care should be taken to position the specimen in such a way that all colors of the design are rubbed in the test. If the areas of colors are sufficiently large, more test specimens should be taken and individual colours should be assessed separately.

Dry Rubbing With the dry rubbing cloth flat in place over the end of the finger of the crock meter, same shouldl be rubbed 10 times to and fro in a straight line along a track 10 cm long on the dry specimen in 10 seconds and with a downward force of 9 N.Wet Rubbing The above described procedure should be repeated with a fresh dry specimen and with wet rubbing cloth. The wet rubbing cloth should be prepared by soaking a fresh rubbing cloth in distilled water and squeezing the same to contain its own weight of water. The staining of the rubbing cotton cloth should be assessed with the help of a grey scale.

CLOLORFASTNESS TO LIGHT TEST:The middle part of the strip is covered with opaque card. It is then exposed to light until the specimen show change in shade (4-5 on the grey scale). The exposure is continued until the specimen is equal to grey scale “4” , at which second segment of specimen is covered with opaque card(B).the exposure is continued until the contrast between exposed and unexposed parts of the specimen is equal to grey scale “3”, at which point the exposure is terminated. Specimen will show two areas that have been exposed for different length of time together with unexposed area. The specimen is given rating of the specimen which shows similar changes.