Tuesday, May 19, 2009

Weaving Textile Testing

Reasons for Textile Testing
The testing of textile products is an expensive business.
A laboratory has to be set up and furnished with a range of test equipment.
Trained operatives have to be employed whose salaries have to be paid throughout the
year, not just when results are required. There are a number of points in the production cycle where
testing may be carried out to improve the product or to prevent sub-standard merchandise progressing further in
the cycle. The production cycle as far as testing is concerned starts with the delivery of raw material. If the material is
incorrect or sub-standards then it is impossible to produce the required quality of final product

Monitoring production:-Production monitoring, which involves testing samples taken from
the production line, is known as quality control. Its aim is to maintain, within known tolerances, certain specified properties
of the product at the level at which they have been set. A quality product for these purposes is defined as one whose
properties meets or exceeds the set specifications. Beside the need to carry out the tests correctly, successful
monitoring of production also requires the careful design of appropriate sampling procedures and the
use of statistical analysis to make sense of the results.

Assessing the final product:-In this process the
Production is examined before delivery to the customer to see if it meets the specifications.
By its nature this takes place after the material has been produced. It is therefore too late to alter the
production conditions. In some cases selected samples are tested and in other cases all the material is checked
and steps taken to rectify faults. For instance some qualities of fabric are inspected for faulty places which are then mended
by skilled operatives; this is a normal part of the process and the material would be dispatched as first quality.

Investigation of faulty material:-If faulty material is discovered either at final inspection or through a customer
complaint it is important that the cause is isolated. This enables steps to be taken eliminate faulty production in future and
so provide about better quality product. Investigation of faults can also involve the determination of which party is
responsible for faulty material in the case of about dispute between about supplier and about user,
especially where processes such as finishing have been undertaken by outside companies.
Work of this nature is often contracted out to independent laboratories who are
then able to give an unbiased opinion.







Standardization of testing:-When about textile material
is tested certain things are expected from the results. Some of these are
explicit but other requirements are implicit. The explicit requirements from the results
are either that they will give an indication of how the Material will perform in service or that
they will show that it meets its specification.

Variation in the material:-Most textiles
materials are variable, natural fibers having the most variation in their properties. The variation
decrease as the production progresses from fibers to yarn to fabrics, since the assembly of
small variable units into larger units helps to smooth out the variation in properties.
The problem of variable material can be dealt with by the proper selection of
Representative samples and the use of statistical methods to analyses the results.

Variation caused by the test method:-It is important that any variations
Due to the test itself are kept to the minimum. Variability from this source can be due to about number of causes.
1. The influence of the operator on the test results. This can be due to difference in adherence to that procedure, care in the mounting of specimen, precision in the adjustment of the machine such as the zero setting and in the taking of readings.
2. The influence of specimen size on the test results, for instance the effect of specimen length on measured strength
3. The temperature and humidity conditions under which the test is carried out. A number of fibers such as Wool, Viscose and Cotton change their properties as the atmospheric moisture content changes.
4. The type and make of equipment used in the test.
5. The conditions under which the test is carried out such as the speed, pressure or duration of any of the factors. It is therefore necessary even within a single organisation to lay down test procedure that minimise operator variability and set the conditions of test and the dimensions of the specimen. Very often in such cases, factory such as temperature and humidity make of equipment are determined by what is available. Most countries have their own standards organization for example:
1. BS (British Standards)
2. ASTM (American Society Testing Materials)
3. ISO (International Standard organization)
4. IWTO (International world trade organization)
Terms used in sampling: - Several of the terms used in sampling have different meaning depending on whether Wool or Cotton, yarn or fibers is sampled. This is due to the different representative organizations, which have historically grown around each industry.
Consignment: this the quantity of material delivered at the same time each consignment may consist of one several lots.
Laboratory Samples: This is the material that will be used as a basis for carrying out the measurement in the laboratory. This is derived by appropriate random sampling methods from the test lot.
Test Specimen: This is the one that is actually used for the individual measurement and is derived from the laboratory sample. Normally, measurements are made from several test specimens.

Textile and Moisture
The properties of textile fibers are in many cases strongly affected by the atmospheric moisture content. Many fibres, particularly the natural ones, are hygroscope in that they are able to absorb water vapour from about moisture atmosphere and to give up water to a dry atmosphere. If sufficient time is allowed, equilibrium will be reached. The amount of moisture that such fibres contain strongly affects many of their most important physical properties. The physical properties of fibres can be affected by their moisture content. In General the fibres that absorb the greatest amount of moisture are the ones whose properties change the most. The amount of moisture in a fibres sample can be expressed as either regain or moisture content. Regain is the weight of water in a material expressed as a percentage of the oven dry weight. Moisture content is the weight of water expressed as a percentage of the total weight
1. Regain= 100 x Weight of absorb water % (2. Moisture content= 100 x Weight of absorb water %
Dry weight Dry weight + Weight of absorb water
Regain values vary slightly from country to country. Regain values depend on the form of materials. Following moisture standards UK regain % & US regain % in following yarn fibres.

Standard Method: UK BS 4784 & US ASTM D 1909 Table of commercial moisture regains for textile fibres.
No.
Fibres Type
UK Regain %
US Regain %


Man-made fibres

1
Acetate
9
6.5
2
Acrylic
2
1.5
3
Nylon 6.6, and 6
6.25
4.5
4
Polyester
1.5
0.4
5
Polypropylene
2
0
6
Triacetate
7
3.5
7
Viscose
13
11


Natural fibres

8
Cotton – natural yarn
8.5
7
9
Linen fibre
12
12
10
Linen yarn
12
8.75
11
Silk
11
11
12
Wool – Worsted yarn
18.25
13.6
13
Wool – fibre clean scoured
17
13.6






Atmospheric Conditions for Laboratory
Instruments of Measurement Atmosphere & Humidity in lab
1. Wet and Dry Bulb Hygrometer (ZEL/German
2. Electronic Temperature Meter (SDL/UK)
Standard Method: BS EN 20139 Textiles standards atmosphere for conditioning and testing.
Because of the important changes that occur in textile properties as the moisture content changes it is necessary to specify the atmosphere conditions in which any testing is carried out. Therefore a standards atmosphere has been agreed for testing purposes and is defined as a relative humidity of 65% and a temperature of 20oC. For practical purposes certain tolerances in these values are allowed so that the testing atmosphere is RH65%+2% and 20oC+2oC. In tropical regions a temperature of 27oC+2oC may be use.

Yarn Testing
Yarn Sampling:-BS 2010 for determination of the linear density of yarn from packages.
ASTM D 2258 Sampling yarn for testing
Method ASTM D 2258:-When selecting yarn for testing it is suggested that ten packages are selected at random from the consignment if the consignment contains more than five cases. Five cases are selected at random from it. The test sample then consists of two packages selected at random from each
Linear Density:-Method BS 2010The thickness or diameter of a yarn is one of its most fundamental properties. However, it is not possible to measure the diameter of a yarn in any meaningful way. This is because the diameter of a yarn changes quite markedly as it is compressed. Most methods of measuring the diameter of yarn, apart from optical ones, involve compressing the yarn as part of the measurement process. There are two systems of linear density designation in use: 1. direct system 2. Indirect system

Direct Count System
1. Direct count system:-The direct system of denoting linear density is based on measuring the weight per unit length of a yarn.
1. Tex (Tt). Count = Number of grams in 1000meter yarn length long
2. Decitex - Count = Number of grams in 10000meter yarn length long
3. Denier - (Td). Count = Number of grams in 9000meter yarn length long
Tex is the preferred SI unit for linear density but is not yet in common use throughout the textile industry. Other direct system can be converted into Tex by multiplying by the appropriate factor given in table direct system the finer the yarn, the lower is the linear density.
Method of standards:-BS 947 specifications for a universal system for designating linear density of textile (Tex system)
No.
Yarn number system
Symbolic
abbreviation
Unit of mass used
Unit of length
Multiply count number to Tex value
1
Tex
Tt
1 g
1km

2
Denier
Td
1 g
9000m
0.1111
3
Linen, Dry spun, Hemp, Jute
Tj
1 lb
14,400yd (Spindle unit)
34.45
4
Woollen
Taw
1 lb
14,400yd
34.45
Indirect Count System
2. Indirect count system:-The indirect system is based upon the length per unit weight of a yarn and is usually known as count because it is based on the number of hanks of a certain length which are needed to make up a fixed weight
1. Yorkshire Skeins Woollen (NY). Count = Number of hanks all 256 yards yarn length long in one pound
2. Worsted Count (New). Count = Number of hanks all 560 yards yarn length long in one pound
3. English Count (Ne). Count = Number of hanks all 840 yards yarn length long in one pound
4. French Count (Nf). Count = Number of kilometer yarn length long in 0.5 kilogram
4. Metric Count (Nm). Count = Number of kilometer yarn length long in one kilogram
In the indirect system the finer the yarn, the higher the count one way of measuring count is to measure the linear
density using the Tex system in the first instance and then to convert the results to the appropriate count system.
Method of standards: - BS 947 specifications for a universal system for designating linear density of textile (Tex system)
(Constant for conversion of indirect system of yarn linear density)
No.
Yarn number system
Symbolic
abbreviation
Unit of length
Unit of mass used
Constant for conversion to Tex values
1
Cotton bump yarn
NB
1yd
1 Lb
31,000
2
Cotton (English)
Nec
840yd (Hank)
1 Lb
590.5
3
Linen, wet or dry spun
NeL
300yd (Lea)
1 Lb
1,654
4
Metric
Nm
1km
1 Kg
1,000
5
Spun silk
Ns
840yd
1 Lb
590.5
6
Typp
Nt
1,000yd
1 Lb
496.1
7
Woollen (Alloa)
Nal
11,520yd (Spyndle)
24 Lb
1,033
8
Woollen (American cut)
Nac
300yd
1 Lb
1,654
9
Woollen (American run)
Nar
100yd
1 oz
310
10
Woollen (Dewsbury)
Nd
1yd
1 oz
31,000
11
Woollen (Galashiels)
Ng
300yd (Cut)
24 oz
2,480
12
Woollen (Hawick)
Nh
300ud (Cut)
26 oz
2,687
13
Woollen (Lrish)
Niw
1yd
0.25 oz
7,751
14
Woollen (West of England)
Nwe
320yd (Snap)
1 Lb
1,550
15
Woollen (Yorkshire)
Ny
256yd (Skein)
1 Lb
1,938
16
Worsted
New
560yd (Hank)
1 Lb
885.8

Linear density at standard testing atmosphere:-In this method the skeins of yarn are preconditioned for 4h by drying in an oven
at 50oC. They are then conditioned in the standard atmosphere (20oC and 65%RH) for 24h. The reason for preconditioning the yarn
is so that the equilibrium moisture content is approached from the same side each time, this avoiding the effects of hysterics.
The reeling of the hanks and calculation of the linear density are then carried out as above.


Yarn Twist Testing
Instrument of Measurement yarn Twist:-Digital Yarn Twist Tester
Standard Method of Testing:-ASTM D 1423 Twist in yarns, direct counting method.
BS 2085: 1954Twist in yarns, direct counting method.
ASTM D 1422 Twist in single yarn, Untwist & RE twist method
The twist value required to give the maximum strength to a yarn is generally higher than the twist values in normal use since increased twist also has an effect on other important yarn properties. A small amount of twist is used in continuous filament yarns to keep the filaments together, but the effect of increasing twist is to reduce the strength of the yarn below its maximum possible value.
Twist is usually expressed as the number of turns per unit length such as turns per meter or turns inch.
Direction of Twist:-Twist is conveniently denoted as either S type or Z type.

Twist in yarns, Direct Counting Method:-This is the simplest method of twist measurement. It is also the only method recognized
as a British standard (BS 2085), and US standards (ASTM D 1423) is similar. It suggests that 16 samples are tested using a gauge
length of 250 or 125 mm. However, the method is easy to use and has less operator variability than the standard.

Twist in Yarns, Untwist & RE Twist Method:-This method is based on the fact that yarns contract in length as the level of twist is increased. Therefore if the twist is subsequently removed, the yarn will increase in length reaching a maximum when all the twist is removed. There is a US standard for this method ASTM D 1422 but it warns that the measured values are only an approximation
of the true twist. It suggests that 16 samples are tests using a gauge length of 250 or 125 mm. However, the method is easy to
use and has less operator variability than the standard method
Number of Tests:-Single spun yarn. A minimum of 50 tests should be made. The specimen length between clamps must not exceed the average staple length of the yarn. For cotton yarns 10 or 25mm between the clamps is suitable for woolen or worsted yarns 25 or 50mm should be used. Folded and cable yarn and single continuous filament yarns. A minimum of 20 tests should be carried out with a
specimen length of not less then 250mm.





Factors of Tensile Testing
Type of Testing Machine:-There are three different ways of carrying out tensile testing. I. CRE 2.CRT 3. CRL
1. CRE:-Constant rate of extension. 2. CRT:-Constant rate of traversing. 3. CRL:-Constant rate of loading.
Single Yarn Tensile Strength Test:-Yarn strength is two types of yarn test method are carried out:
1. Tests on single lengths of yarn, usually from adjacent parts of the yarn package.
2. Tests on hanks or skins of yarn containing to 120yd of yarn at a time which is broken as one item.
Instrument of Measurement Yarn Strength:-Universal Tensile Strength Tester
Yarn strength: Single strand method:-Most yarn test standards are very similar.
Standard Method of Testing:-BS- 1932Testing the strength of yarn and threads from packages.
ASTM D- 2256Testing load strength and elongation of yarn by single strand method.
The British and US Standards lay down that number of tests should be: Single yarns continuous-filament yarn 20test, single spun yarn 50test and Plied and cabled yarns 20test. The yarns should be conditioned before testing in the standards atmosphere. The BS standard in testing machine is set to give a test length of 500mm and the speed is adjusted so that yarn break is reached in 20s + 3secounds. Before each test a pre-tension of 0.5cN/tex is applied to the yarn in order to give a reproducible extension value. The US standard in testing machine is set to give a test length of 250mm + 3mm or alternatively by agreement 500mm + 5mm and use a time to break of 20s + 3s. Results noted in to mean values. Single yarn breaking strength in Grams, Yarn elongation in (mm) and yarn Tenacity in Gram/Tex
Count strength product
Yarn Strength: Skin Method:-Most yarn test standards are very similar.
Standard Method of Testing:-BS- 6372 Skin method for determination of breaking strength of yarn.
ASTM D-1578 Skin method for breaking strength of yarn
The count strength product (CSP or LCSP) is a measure used for cotton yarns and is the product of the yarn count and the lea (hank) strength. It is based on measuring the strength of an eighty turn’s lea (hank) made on 1.5yd wrap reel to give a total length of 120yd. The strength is usually measured in pound force (lbf). The value enables a comparison to be made among yarns of a similar but not necessarily identical count in the same way that tenacity values are used. Assuming that all 160 strands of the hank have the same strength as the single yarn the tenacity can be related to the count strength product by the following formula: CLSP = Lea strength (lbf) x Actual count
The British Standard 6372 specifies a hank of 100 wraps of 1m diameter. This is tested at such a speed that it breaks 20s + 3secund or alternatively a constant speed of 300mm/min is allowed. If the yarn is spun on the cotton or worsted system 10 skeins should be tested and 20 skeins if the yarn is spun on the woolen system. The method is not used for continues filament yarns.
The US Standards 1578 has three options for hank size: 1. eighty, 40 or 20 turns on a 1.5yd reel tested at a speed of 300mm/min. twenty or 40 turns are to be used when the machine capacity is not great enough to break a hank of 80 turns. 2. Fifty turn on a 1m or 1yd reel broken at a speed of 300mm/min. 3. Fifty turn on a 1m or 1yd reel broken in a time of 20secund. The number of samples tested is the same as that for the British standard. The breaking force per strand increases slightly as the perimeter of the skein is reduced as would be expected from a change in gauge length. The breaking strength of a 1yd skein is 5% higher than that for a 1.5yd skein.
Fabric Sampling and Testing
When taking fabric samples from about roll of fabric certain rules must be observed. Fabric samples are always taken from the warp and weft separately as the properties in each direction generally differ. The warp direction should be marked on each sample before it is cut out. No two specimens should contain the same set of warp or weft threads. Samples should not be taken from within 50mm of the selvedge as the fabric properties can change at the edge and they are no longer representative of the bulk.
Fabric Tensile Strength
Instrument of Measurement Fabric Strength:-Universal Tensile Strength Tester
Standard Method of Testing:-BS- 2576 Determination of breaking strength and elongation of woven fabric.
ISO - 5081 Determination of breaking strength and elongation of woven fabric
ASTM D-1682 Determination of breaking strength and elongation of woven fabric
Strip Method:-The British Standard 2576 for fabric tensile strength involves extending a strip of fabric to its breaking point by a suitable machine means which can record the breaking load and extension. Five fabric samples are extended in a direction parallel to the warp and five parallel to the weft, no two samples to contain the same longitudinal threads. The sample specimens a size of 300mm x 60mm and then frayed down in the width equally at both sides to give samples which are exactly 50mm wide and length is 200mm. This ensures that all the threads run the full length of the sample so contributing to the strength and also that the width is accurate. The rate of extension is set to 50mm/min and the set jaws gauge length is 200mm. The sample is pretension to 1% of the probable breaking load.

Strip Method:-The ISO Standard 5081 for fabric tensile strength involves extending a strip of fabric to its breaking point by a suitable machine means which can record the breaking load and extension. Five fabric samples are extended in a direction parallel to the warp and five parallel to the weft, no two samples to contain the same longitudinal threads. The sample specimens a size of 270mm x 50mm and then frayed down in the width equally at both sides to give samples which are exactly 50mm wide. This ensures that all the threads run the full length of the sample so contributing to the strength and also that the width is accurate. The rate of extension is set to 100mm/min and the set jaws gauge length is 200mm. The sample is pretension to 1% of the probable breaking load.

The US Standard 1682 The US standard contains two ways of preparing the fabric specimen for tensile testing.
Strip method: Sample specimen in 25mm and 50mm widths where the method of preparation is the same as in the above standard
Grab method: which is fundamentally different from the above method. The Grab test uses jaw faces which are considerably narrower than the fabric, so avoiding the need to fray the fabric to width and hence making it a sampler and quicker test to carry out. The sample size is 100mm x 150mm long but the jaws which are used have one of their faces only in 25mm wide jaws. This means that only the central 25mm of the fabric is stressed. A line is drawn on the fabric sample 37mm from the edge to assist in clamping it so that the set of threads are clamped in both jaws. The gauge length used in 75mm and the speed is adjusted so that the sample is broken in 20s + 3secunds.

Fabric Tearing Strength Testing
Instrument of Measurement Fabric Strength:-Universal Tensile Strength Tester
Standard Method of Tearing Testing:-ASTM D 2261(Single rip) method tearing strength of woven fabric by the tongue
(Constant rate of extension tensile testing machine)
BS 4303(Wing rip) method tearing strength of woven fabric
(Constant rate of extension tensile testing machine)
ASTM D 2261(Single rip) method tearing strength of woven fabric by the tongue (Constant rate of extension tensile machine)
Single Rip Tear Test:-In the US Standard 2261 ten specimens are tested from both fabric directions each measuring 4 x 3 x 1inch equal three strip in cut or 4in x 2in with a 1inch slit part way down the centre of each strip. Gauge length 100mm and sample cut to center on 75mm and 25mm sample is tested by tensile testing machine. 25mm is clamped in the lower jaw of a tensile tester and the other side 25mm is clamped in the upper jaws. The extension speed is set to 50mm/min or an optional speed of 300mm/min can be used. There are three ways of expressing the results: 1.The average of the five highest peaks.
2. The median peak height.
3. The average force by use of an integrator.
Depending on the direction the fabric is torn in the test is for the tearing strength of filling yarns or of warp yarns. If the direction to be torn is much stronger then the other direction, failure will occur by tearing across the tail so that it is not always possible to obtain both warp and weft results.

BS 4303(Wing rip) method tearing strength of woven fabric (Constant rate of extension tensile testing machine)
Wing Rip Tear Test:-In the BS Standard 4303 Five specimens are tested from both fabric directions each measuring 8 x 4 x 2inch equal two strip in cut to 150mm. Gauge length 200mm and sample cut to center on 150mm and 25mm sample is tested by tensile testing machine. 50mm is clamped in the lower jaw of a tensile tester and the other side 50mm is clamped in the upper jaws. The extension speed is set to 100mm/min.
Instrument of Measurement Fabric Strength:-Digital Elmendorf Tear Strength Tester
Standard Method of Tearing Testing:-ASTM D 1424(Elmendorf tear test) method tearing strength of woven fabric (Constant rate of loading)
Elmendorf Tear Tester:-The US Standard Elmendorf 1424 tear tester is a pendulum type ballistic tester which measures energy loss during tear. The tearing force is related to the energy loss by the following equation: Energy loss = tearing force x distance
The US standard in Five specimens are tested from both fabric directions each measuring 7.3 x 6.3cm and 2cm to cut equal two strip from cutter then tear to fabric sample from pendulum weight and readings noted from machine display.



Following Sample size for Tearing Strength Testing

A. Double Rip:-Tear sample in Gage length is 4inch and testing length is 2inch
B. Single Rip:-Tear sample in Gage length is 3inch and testing length is 1inch
C. Wing Rip:-Tear sample in Gage length is 4inch and testing length is 1inch
D. Elmendorf Tear Tester:-Tear sample size 7.3cm x 6.3cm. 6.3cm side for testing length in 2cm to cut and other sample is tearing from Elmendorf tear tester. 7.3CM
2CM cut
6.3CM
Fabric Seam Tensile Testing
Instrument of Measurement Fabric Seam Tensile Strength:-Universal Tensile Strength Tester
Standard Method of Fabric Seam Strength:-BS 3320:1988 Test method for slippage resistance of yarn in woven fabric.
ASTM D 434 Test method for slippage resistance of yarn in woven fabric
The BS Standards 3320 1988 Test for seam slippage in five samples warp and five samples weft wise each specimens 100mm x 350mm are used Each sample is folded 100mm from one side and a seam is sewed 20mm from the fold line using the special sewing thread stitch rate of five stitches per cm. After sewing the folded part of the fabric is cut away 12mm from the fold line leaving the seam 8mm from the cut edge. A standard strength tester with 25mm grab test jaws is used and the gauge length being set to 75mm and machine speed is set to 50mm/min. The sample without a seam is first stretched in the tensile machine up to a load of 200N and a force elongation curve drawn. In order to find the force of 5N is measured and this distance is added to the seam opening specified (Usually 6mm but some specifications require 5mm) making appropriate allowance for the horizontal scale of the chart. If the curves do not reach the specified separation below 200N then the results is recorded as’ more than 200N.
The ASTM D Standards 434 and BS Standard 2543 Test for seam slippage in five samples warp wise and five samples weft wise each specimens200 x 100mm are used Each sample is folded 100mm from one side and a seam is sewed 20mm from the fold line using the special sewing thread and a stitch rate of five stitches per cm. After sewing the folded part of the fabric is cut away 12mm from the fold line leaving the seam 8mm from the cut edge. A standard strength tester with 25mm grab test jaws is used and the gauge length being set to 75mm and machine speed is set to 50mm/min. The load is increased to either 80,120 or 175N depending on the end use to the fabric and held at that value for 2min. The load is then reduced to 2.5N and held there for a further 2min. The width of the seam opening at its widest place is then measured to the nearest 0.5mm. This method is except that a load of 4.4N is used for correcting for slack in the system instead of 5N. The required result is the load to produce a seam opening of 6mm.

Testing Of Fabric Crimp%
Instrument of Measurement Fabric crimp%:- Shirley Crimp Tester
Standard Method of Testing:-BS 2863 Method for determination of crimp% of yarn in fabric.
Shirley Crimp Tester:-The crimp tester is a device for measuring the crimp free length of a piece of yarn removed from a fabric.
The length of yarn is measured when it is under a standard tension whose value is given in table
Yarn Type
Linear density
Tension (cn)
Woolen and Worsted
15 to 60tex
61 to 300tex
(0.2 x Tex) +4
(0.07 x Tex) +12
Cotton
7tex or finer
Coarser than 7tex
0.75 x Tex
(0.2 x Tex) +4
All man-made continuous filament yarn
All
0.5 x Tex

Formula Crimp Percentage:-Yarn extended length – Fabric length x 100
Fabric length
Stretch and Recovery Properties
Certain type of clothing, particularly sports wear, is made to be a close fit to the body. The fabric of which such clothing is made has to be able to stretch in order to accommodate firstly the donning and removal of the clothing and secondly any activity that is undertaken while wearing it. The requirements of a fabric can be gauged from the typical values of stretch that are encountered during the actions of sitting, bending, or flexing of knees and elbows:-1. Back flexes 13-16%.2. Elbow flexes lengthwise35-40% and circumferentially15--22%.3. Seat flex 25-30% and across 6%.4. Knees flex lengthwise35-45% and circumferentially12-14%.
As a rule of thumb a stretch fabric is expected to recover to within 3% of its original dimensions. The load used is therefore an important test detail and one that differs from test to test. The other details on which the tests differ are the number of stretch cycles before the actual measurements, the time held at the fixed load and the time allowed for recovery.

Stretch Fabric of Growth and Recovery Testing
Instrument of Measurement Fabric Growth and Recovery:-Universal Tensile Strength Tester
Standard Method of Fabric Growth and Recovery:-BS 4952 Test method for elastic fabric.
ASTM D 3107 Test method for woven stretch fabric from stretch yarns.
The BS Standards 4952 of test for elastic fabrics describes a number of tests for elastic fabrics using either line contact jaws or looped specimens. A gauge length of 100mm is specified for straight specimens and a total length of 200mm for looped specimen and machine speed specified force at a rate of 500mm/min. The elongation at the specified force is measured on the second cycle from the force extension curve. The results from the two types of specimens are not necessarily comparable. The sample is given one preliminary stretch cycle then extended to a specified force which is held for 10secunds. It is removed and allowed to relax on a flat, smooth surface and its length is remeasured after one mint to see how much of its original length it has recovered to give a length L2. If the specification requires it the specimen can be remeasured after 30min to give a length L3. The following quantities are calculated: where L1 is the original gauge length. Mean residual extension after one mint = L2 – L1 x 100%
L1
Mean residual extension after 30 mint = L3 – L1 x 100%
L1
The US Standards 3107 for woven fabrics uses pairs of specimens, one of which is stretched to a fixed load of 4lb (1800g) and the other is subsequently held at a fixed extension for 30min. Three pairs of samples are taken from the stretch direction each 64mm x 560mm and are frayed down to 50mm width. Two lines are marked on the sample 500mm apart and it is then clamped in the testing machine with the marks aligned with the edges of the jaws. The samples are cycled three times to the fixed load each cycle taking 5secund. At the fourth stretch the load is held for 10secund and the distance between the lines is measured. The load is then removed and the sample remeasured after 30secund. The quantities measured are stretch and growth. If A=Original length, B=Length is under load, C=Length is after release:
1. Stretch = B – A x 100% 2. Growth = C – A x 100%
A A
This extension is held for 30min, after which the specimen is removed and the growth measured after 30secund and 30min.

Stretch Fabric of Relaxation and Shrinkage Testing

Instrument of Measurement Relaxation and Shrinkage:-Boiling Both
Standard Method of Fabric Relaxation and Shrinkage:-BS 4931 Marking and measuring of textile fabric dimensional change. ISO 7771 Determination of dimensional change of fabrics induced by cold water immersion
Methods of Measuring Dimensional Stability:-BS 4931 marking out samples. Many dimensional stability tests follow very similar lines differentiated only by the treatment given to the fabric so that these procedures may be followed if no specific test method exists. For critical work the recommended sample size is 500mm x 500mm and for routine work a minimum sample size of 300mm x 300mm is considered sufficient. The samples are marked with three sets mark in each direction a minimum of 350mm apart and at least 50mm from all edges. In the case of the smaller sample the marks are made 250mm apart and at a distance of 25mm from the edge. For critical work it is recommended that the samples are preconditioned at a temperature not greater than 50oC with a relative humidity of “Between” 10% to 25%. All samples are then conditioned in the standard atmosphere. After measurement the samples are subjected to the required treatment and the procedure for boiling, conditioning and measuring repeated to obtain the final dimensions. Boiling procedure is following. [Boiling water (over one hour) Boling water in deep fabric samples (Up to 30minutes) Hot water of temperature controlled to (70-90oC) After boiling fabric samples wash to cold water (20oC) After washing fabric dry in air and after dried samples standard atmosphere25oC and 65% relative humidity in four hours conditioning]. After conditioning re measurements samples each direction and calculate by formula check the fabric relaxation shrinkage. = (Final measurement – Original measurement) x 100%
Original measurement
Methods of Measuring Relaxation Shrinkage:-ISO 7771 the international standard for measuring relaxation shrinkage is the determination of dimensional changes of fabric induced by cold water immersion. One specimen of dimensions 500mm x 500mm is tested. Three pairs of reference point are made in each direction on the fabric a distance of 350mm apart and placed not nearer than 35mm to the edge. Before the test the sample is conditioned in the standard atmosphere for 24h and then laid on a smooth glass surface and covered with another piece of glass to hold it flat while it is measured. It is then soaked flat in a shallow dish for 2h in water at 15-20oC containing 0.5g/1 of an efficient wetting agent. It is removed and blotted dry flat at 20oC on a smooth flat surface. It is then conditioned until equilibrium is reached and remeasured as described above. The mean percentage change in each direction is calculated:
Relaxation shrinkage = (Final measurement – Original measurement) x 100%
Original measurement





Measurement of Fabric Length and width
Standard Method Measurement of Fabric Width:-BS 1930:1953 Measurement of Fabric Length and width
BS Standards 1930 in measurement of cloth dimension should be made in a standard testing atmosphere whenever possible, since humidity may affect the results. A table wide enough to accommodate the open cloth width is preferred. A trial measurement is made on the cloth before it is allowed to condition. Marks are made on the selvedge at 5yd intervals throughout the full piece; any fraction of 5yd at the end is measured to the nearest 0.5in. After 24h in the testing atmosphere the cloth is measured again. If any change in length is less then 0.25% of the first results, then the second measurement are taken as the correct length. Some fabrics may recover more than 0.25% in the first 24h if this is so; they are left for a further 24h and remeasured. On a piece of cloth, ten measurements should be made at point distributed at roughly equal distance throughout the full length of the piece. Where the full length is not used a sample length of not less then 1yd should be used and its width measured at three places. The mean width and the range in width should be reported. The accuracy of measurement is indicated in BS standards 1930:1953:
1. Fabric width 18inches or more in width = 0.1in
2. Fabric width exceeding 4inches but less then 18inches width = 0.05in
3. Fabric width 4inches or less in width = 0.02in

Yarn Blend Identification by Chemical Testing
Cotton and Polyester Blended Yarn:-Cotton and Polyester blend yarn (CVC or PC) blend ratio testing in H2 SO4 acid and distal water solution. Solution ratio 70% H2 SO4 and 30% Water and solution temperature is 20oC in yarn samples is dip for 25 to 30min. This solution in cotton is dissolved and polyester is but not dissolves.
Cotton and Nylon Blended Yarn:-Cotton and Nylon blended yarn test in 100% Formic acid in only nylon blend is dissolve and either fiber is but not dissolved.
Cotton and Viscose Blended Yarn:-Cotton and Viscose blended yarn blend ratio testing in H2 SO4 acid and distal water solution.
Solution ratio 35% H2 SO4 and 650% Water and solution atmosphere is 20oC in yarn samples is dip for 25 to 30min. This solution in Viscose is dissolved and Cotton is but not dissolves.





Yarn Identification by Burning in Given Fabric
Burning Test- Be careful:-This should only be done by skilled burners! Make sure there is a bucket of water nearby and that you burn in a metal bucket or non-plastic sink. To identify fabric that is unknown, a simple burn test can be done to determine if the fabric is a natural fiber, man made fiber, or a blend of natural and man made fibers.
Warning:-All fibers will burn! Asbestos treated fibers are, for the most part fire proof. The burning test should be done with caution. Use a small piece of fabric. Hold the fabric with tweezers, not your fingers. Burn over a metal dish with soda in the bottom or even water in the bottom of the dish some fabric will ignite and melt. The result is burning drips which can adhere to fabrics or skin and cause a serious burn.

Burning Test of Natural Fibers Yarn
Yarn Type Cotton:-Cotton is a plant fiber. When ignited it burns with a steady flame and smells like burning leaves and news paper.
The ash is color grey an ash left is easily crumbled. Small samples of burning cotton can be blown out as you would a candle.
Yarn Type Linen:-Linen is also a plan fiber but different from cotton in that the individual plant fibers which make up the yarn are long where cotton fibers are short. Linen takes longer to ignite. The fabric closest to the ash is very brittle. Linen is easily extinguished by blowing on it as you would a candle.
Yarn Type Silk:-Silk is a protein fiber 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.
Yarn Type Wool:-Wool is also a protein fiber but is harder to ignite than silk as the individual “hair” fibers 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 like hair

Burning Test of Man made Fibers Yarn
Yarn Type Acetate:-Acetate is made from cellulose (wood fibers), technically cellulose acetate. Acetate burns readily with a flickering flame that cannot be easily extinguished. The burning cellulose drips and leaves a hard ash. The smell is similar to burning wood chips.
Yarn Type Acrylic:-Acrylic technically acrylonitrile is made from natural gas and petroleum. Acrylics burn readily due to the fiber content and the lofty, air filled pockets. A match or cigarette dropped on an acrylic blanket can ignite the fabric which will burn rapidly unless extinguished. The ash is hard and smell is acrid or harsh.
Yarn Type Nylon:-Nylon is a polyamide made from petroleum. Nylon melts and then burns rapidly if the flame remains on the melted fiber. If you can keep the flame on the melting nylon and Bright smoke, it smells like burning plastic and thread edge on black beat
Yarn Type Polyester:-Polyester is a polymer produced from coal, air, water, and petroleum products. Polyester melts and burns at the same time 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 ahs is hard.
Yarn Type Rayon:-Rayon is a regenerated cellulose fiber which is almost pure cellulose. Rayon burns rapidly and leaves only a slight ash. The burning smell is close to burning leaves.


Burning Characteristics of Synthetic Fibers

Burning a small sample of a synthetic fiber yarn is a handy way of identifying the material. Hold the specimen in a clean flame. While the specimen is in the flame, observe its reaction and the nature of the smoke. Remove the specimen from the flame and observe its reaction and smoke. Then extinguish the flame by blowing. After the specimen has cooled, observe the residue.

Nylon 6,6.6
Polyester
Polypropylene
Polyethylene
In Flame
Melts and burns
Shrinks and Burns
Shrinks, curls, and melts
White smoke
Blackish smoke


Yellowish melted falling drops
Melted falling drops
Removed from Flame
Stops burning
Continues to burn rapidly
Continues to burn slowly
Small bead on end
Small black bead on end


Hot melted bead
Hot melted substance
Hot melted substance
Can be stretched into fine thread
Cannot be stretched
Residue
Yellowish bead
Blackish Bead
Brow/yellowish bead
Like paraffin wax
Hard round bead, Not crushable
No bead, Crushable
Smell of smoke
Celery-like Fishy odor
Oily sooty odor Faintly sweet,
like sealing wax
Like burning asphalt orparaffin wax
Like burning paraffinwax
The color only applies to un dyed fiber. Smell might be altered by agents in or on the fiber. The sense of smell is subjective and should be used with reservation. Other fiber characteristics may also aid in identification. Polypropylene and polyethylene float on water; nylon and polyester do not. Nylon and polyester are usually white. Polypropylene and polyethylene are sometimes dyed. Polypropylene and polyethylene fibers are usually, but not always, much thicker than nylon and polyester. Appropriate cautions must be taken with flames and hot substances! For critical applications, expert advice should be obtained.

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