Textile testing of finished goods

Testing of textile finished goods

1. Physical Properties:a) Appearancecolor & uniformity of finished yarn or fabric- visual assessment only.a) Tensile strength of finished yarnb) CSP of finished yarnc) Tear strength of finished fabricd) GSM of fabric of finishede) Shrinkage Test of Woven fabric and Knit fabric.

2.Finished goods Qualities:1) What is a grey scale & staining scale? How fastness grading is done?2) Fastness to washing3) Fastness to Crocking or Rubbing fastness4) Fastness to water5) Fastness to perspiration6) Fastness to peroxide bleach7) Fastness to Chlorine or chlorinated pool water fastness8) Fastness to Mercerising9) Fastness to Hydrolysis10) Fastness to Dry-cleaning11) Fastness to light12) Pilling Tests13) What is whiteness Index14) What is total color difference or DE15) Method of Detecting Starch and PVA16) Method of testing desizing efficiency17) Measurement of Absorbency18) Antimicrobial Tests19) Flammability Test20) Detection & estimation of formaldehyde content in Textiles

b) Tensile strength of finished yarn-Fabric samples are clamped in jaws of a tensile tester & pulled apart until they break. Three samples are tested across warp & three across west & average breaking strength established is expressed in Newtons. BS 2543 states that tensile strength should be as follows for different grades of intended duty:

c) Tear strength of finished fabricThis test measures force required to continue a tear which has already been started in fabric. A cut is made in a rectangular sample to form two "tongues" and reference lines are marked to indicate point tear is to be continued to. One tongue is then placed in upper jaw of a tensile tester, other tongue in lower jaw, & two jaws opened to continue the tear to reference line. Average tear strength is then calculated.

Again, BS 2543 specifies minimum tear strength for different uses:Occasional domestic/Light domestic = 15NGeneral domestic/Severe domestic = 20NSevere contract = 25N

d) Shrinkage test of woven fabric and knit fabricBefore doing any Shrinkage test, the sample should be conditioned in an atmosphere of 65% R.H. & 24 to 27C for a minimum of 4 hours.

Woven fabric shrinkage-AATCC-135 Method (ISO 3759)1. Sample size 50 cms X 50 cms2. Marking area 35 cms X 35 cms3. Samples weight should be 1.8kg +/- 0.1kg (If sample weight is less than 1.8kg put dummy cloth & maintains weight of 1.8kgs).4. Liquor Ratio : 1:505. Suitable detergent (0.5%) on weight of sample i.e. 1.8kgs6. At 400C for 60mins in Wash-cator.7. Dry sample at 60-650C using tumble dryer.8. Press sample in flat bed hot press at 1500+/- 15C with 30gms/cm2pressure.9. Cool sample and measure.

Shrinkage for cotton hosiery IS-33261. Liquor Ratio 1:502. Temperature : 30 to 35C3. Suitable Wetting agents (detergent) 0.5% on the weight of the hosiery sample.4. Sample size 20 x 20 cms.5. Marking area 14 x 15 cms (mark with marking scale).6. Time 2 hours at 30 to 35C7. After that dry at room temperature.8. Measure.9. Shrinkage % = [100 x (a-b)]/aWherea = Distance between two ends before treatment b = Distance between two ends after treatment.

Grey scale for assessing change in shadeEN ISO 105-A03 / IUF 132 / VESLIC C 1211This Grey Scale is for assessing degree of change in shadecaused to a dyed Textile fabric/yarnincolor fastness tests. For example, chnage of shade of wool & cotton fabrics in wash fastness, perspiration fastness, etc.

Scale consists of nine pairs of gray color chips each representing a visual difference & contrast.

Fastness rating goes step-wise from:Note 5=no visual change (best rating) to Note 1 = a large visual change (worst rating).

Gray scale has 9 possible values:5, 4-5, 4, 3-4, 3, 2-3, 2, 1-2, 1.

It is now quite common to measure Grey Scale change in color instrumentally. This is made using a suitable reflectance spectrophotometer according to test method procedure,

EN ISO 105-A05.Grey scale for assessing stainingEN ISO 105-A03 / IUF 132 / VESLIC C 1211This Grey Scale is for assessing degree of stainingcaused by a dyed Textile/yarnincolor fastness tests. For example, staining of wool & cotton fabrics in wash fastness, perspiration fastness, etcScale consists of nine pairs of gray color chips each representing a visual difference & contrast.

Fastness rating goes step-wise from:Note 5= no visual change (best rating) to Note 1 = a large visual change (worst rating).Grey scale has 9 possible values:5, 4-5, 4, 3-4, 3, 2-3, 2, 1-2, 1.

It is now quite common to measure Grey Scale for assessing staining instrumentally. This is made using a suitable reflectance spectrophotometer according to test method procedure, EN ISO 105-A04.

Fastness to washingColor fastness:Resistance of a material to change in any of its color characteristics, when subjected to washing is called color fastness to washing.

General principle:A specimen of textile to be tested, with adjacent fabric attached is subjected to washing under specified conditions. Te extent of any change in color & that of staining of adjacent fabric are assessed & rating is expressed in fastness numbers.

There are two types of adjacent fabrics; (1) single fibre fabric & multiple fibre fabric. In case of multitier fabric only one specimen is required & in of single fiber fabric two adjacent fabrics are required.

There are various colorfastness tests. Details of some of the tests are given below.

Fastness to washing:In test, change in color of textile & also staining of color on adjacent fabric are assessed. A 10 x 4cm swatch of coloured fabric is taken & is sandwiched between two adjacent fabrics & stitched. Sample & adjacent fabric are washed together. Five different types of washing are specified as different washing methods.

Fastness to wash

Sl.noMethodWashing severitySoap+Soda (g/l)Time(mins)Temp(oC)Steel balls

1IS:687:79Very mild like hand wash53040+/- 2Nil

2IS:3361:795 times severe than method 154550+/- 2Nil

3IS:764:79Mild washing5 + 23060+/-2Nil

4IS:765:79Severe washing5 + 23095+/-210

5IS:3417:79Severe washing5 + 24 hrs95+/-210

Solution for washing should be prepared to required temperature of washing. M:l ratio is 50:1.

After soaping treatment, remove specimen, rinse twice in cold water & then in running cold water under a tap. Squeeze it & air dry at a temperature not exceeding 60C. Change in color & staining is evaluated with help of grey scales.

Fastness to crocking or rubbing fastnessRubbing/Crocking fastnessReactive dyes being water soluble it is difficult to achieve same level of wet rubbing ratings as compared to insoluble dyestuff & also dry rubbing. With water soluble dyes, apart from bleeding of dyestuff from rubbed area, finely distributed substrate particles also rub off on surface of crock meter cloth.

Problem is increasing with higher depths & fabrics like towels, corduroy etc. with rough surface. Whileevaluatingratingit is necessary to ignore such rub-off particles appearing on crock meter cloth & consider only staining of dye on rubbed cloth.

Instrument used for checking is standard crock meter. However, test is quite sensitive and for getting consistent result, it is necessary to use standard crock meter cloth, maintain uniform pressure for applying rubbing strokes & number of strokes. Besides, for wet rubbing, % moisture on crock-cloth has to be kept to uniform level. For ISO-105 x 12 test methods, rubbing cloth that has been wetted with water has to be squeezed to contain its own weight of water. For AATCC 116-1995 methods, wet pick up is to be maintained between 65 5% by squeezing wet crock meter cloth using an AATCC blotting paper. Any variation in moisture content can lead to deviation in rating. With high amount of moisture i.e.., wet pick up, ratings will be lower. Degree of staining is visually assessed using Grey scale for changes of colour with grade of 1-5 where rating of 5 signify negligible change & 1 maximum change.

In order to get maximum achievable wet rubbing rating, with reactive dyes, it is absolutely necessary to remove all unfixed hydrolyzed dyes by proper soaping/washing of sample before evaluating ratings. Extraction with pyridine can be done to check removalof hydrolyzed dyestuff.

1. Effect of depth of shade/selection of dyes:For reactive dyes with high solubility & good washing fastness properties, rating will be relatively higher. However, in deep shades, even with dyes with good washing fastness, a fastness rating of 2-3 on grey scale is achievable & is considered satisfactory & acceptable. Liquid introduced with wet crocking cloth results in all cases in deterioration in rub fastness of up to 2 points in comparison to dry rubbing.

2. Effect of mercerisingColour transfer is relatively less, for mercerised cotton & rubbing fastness grade is higher. Due to change in fiber structure on mercerising, there is a 30% less extent of removal of fiber particles, during wet rubbing and lesser amount of colour on fibre for same visual depth of shade.

3. Effect of finishing treatmentsDifferent types of finishing treatment viz. softness, poly-siloxanes, Zr-compounds, fluorocarbon, chitosan & cellulase enzymes etc. applied to dyes, fabrics do not show improvements in wet rubbing ratings. With some of cross linking agents, rubbing fastness grade is lowered by 1/2 to 1 unit. In one of recent study it is claimed that for reactive dyed blacks & bordeaux materials, with polyacrylate finishes there is some improvement in wet rubbing fastness rating.

Method of testing desizing efficiencyDesizing efficiency test:Desizing efficiency is found in two ways conventional and TEGEWA method.

Conventional method:In this method we first take weight of sized fabric, let it be W1. Then desize fabric, dry & take weight, let it be W2. After that fabric is treated with 3gpl (35%) HCl at 70oC for 30min. dry & take weight of fabric. Let it be W3.Total size = W1-W3.Residual size = W2-W3.Desizing efficiency = (Total size Residual size)/Total size X 100.

Tegewa rating:Reagent: potassium iodide (10gm. of KI (100%) in 100ml water, add 0.6358gm of iodine (100%) stir & shake; iodine is completely dissolved. Fill up to 800ml with water then complete to 1000ml with ethanol. (Shelf life approx 6 months only).

Method:1. Spot drop wise solution onto fabric.2. Rub in gently.3. Assess change of color.Note: Test must be carried on fabric cooled down to room temperature; residual alkalinity has to be neutralities prior to test.

Assessment:Grey fabric:No change of color = no starch size present.Pale blue to bluish = presence of starch size or blendViolet =of starch size with synthetic size

Desized fabric:Pale blue to bluish violet = refer to violet scale TEGEWA that indicates residual Starch content.