1. The document discusses textile materials testing, noting that it examines physical, mechanical, and chemical properties of textiles. Testing is often done during manufacturing to eliminate faults before production. 2. It outlines seven reasons for textile testing: conforming to specifications, quality promotion, quality control, government regulations, product evaluation, failure analysis, and product development. 3. Proper sampling methods and sample sizes are discussed, including simple random sampling, systematic sampling, stratified sampling, and cluster sampling. Atmospheric conditions like temperature and humidity that can affect test results are also covered.

1. DIRE DAWA UNIVERSITY INSTITUTE OF TECHNOLOGY
Teng4221: Textile Materials Testing
School of Textile, Apparel and Fashion Design
Department of Textile Engineering
Course manager Mr. Negesa Bayesa
Academic year 2015 E.C
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2. Textile materials testing
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3. Introduction
 Textile testing can be defined as "Examining and determining the physical, mechanical
and chemical properties of a textiles.”
 Often, testing is completed during the creation of textiles to ensure any faults or
problems are eliminated before manufacturing and there are many factors that can
affect test results, such as, Atmospheric conditions, methodology and the testing
instruments used.
 The testing of textile products is an expensive business. A laboratory has to be set up
and furnished with a range of test equipment.
 Why testing is needed in textile process?
1, Testing for conformance to specification requirements
 Conformance testing is testing to see if an implementation meets the requirements of a
standard or specification. The requirements or criteria for conformance must be
specified in the standard or specification, usually in a conformance clause or
conformance statement
Specification is a list of requirements to be met by a product ( from ASTM definition)
 E.g., construction characteristics & performance characteristics and/or both
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4. Cont.…
 Specification test has so many advantages:
 prevention of deterioration in quality by manufacturers using inferior quality
 production of goods of known performance
 opportunity for manufacturer to produce exactly what is required by the customer
 the customer really know what he wants and can frame a specification in the right
way, etc.
2, Testing for quality promotion
An extension of manufacturing to specification in which marketing of the product centers
around its serviceability( fitness for purpose)
Testing can be done by manufacturer or external certifying agencies/organizations
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5. Cont.…
3, Testing for quality Control
performing inspection/testing at predetermined intervals on purchased raw –materials,
at various stages in the manufacturing of products and product testing
any process should be supervised or controlled while in operation, because when
processing goes out of control the amount of waste and the number of seconds increase
,cost goes up and temper also goes high
• higher end breakage in spinning and winding
• excessive loom stops due to warp and weft breaks -affects the operatives as well
as production
a usual precondition for quality control test is meeting the requirements of a
performance specification
a plan of production requires certain standard quality levels to which materials in process
must conform for this ,the quality control scheme measure weight-per-unit –length of
lap, sliver, roving or yarn counts
the object of product testing is to access or find –out the performance quality of a
finished article in actual service
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6. Cont.…
4, Testing for adherence to Government
Regulations
Regulations may issued by Government
to product for health care and safety
concern
e.g., Regulation issued by USA
Government under Flammable Fabrics
Act -make manufacturer of the
children's sleepwear and all other
apparel rugs, carpets ,mattresses and
mattress pads responsible for meeting
specific flammability requirements
• 5, Testing to Evaluate products
To adopt or copy other’s product
• “why is our competitor’s product
selling better than ours”?
• “can we find out this or was made
so we can knock it off” (make
approximate copies to be sold at a
lower price)
• “which of these products offered
to us is best to meet our needs?”
Any kind of product evaluation or
comparison must be viewed in the
context of a specific end use. Fabric A
might well be more suitable for blouses
and fabric B for children wear or
playwear
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7. Cont.…
6, Testing to analyze fabric failure
whenever a product proves unserviceable in one way or another, the manufacture of the product
must wonder why?
the manufacturer should also view the failure as an opportunity to learn how to the product better
unserviceable product for laboratory examination –customer returns
7, Testing as part of product development
whenever, manufacture of a new product is under consideration it is a usual to test the quality
characteristics of the product samples very carefully before launching in to full production
The development process on complicated and innovative new products can go on for years ,even
after full commercial production has started
Product development test is considered as a form of applied research
The experimental works are carried out in research institutes on the actual processing
machinery
Investigations and further research are being carried out for better ,cheaper and quicker
methods of manipulating fibers & yarns
The success achieved is often measured by the improvement in one or more
characteristics of the material delivered after change in machine design or setting
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8. Cont.…
The nature of research is to conduct systematic inquires into subject.
The researcher collects relevant data, or facts, and invents falsifiable hypotheses
about relations among the facts
Experiments or tests may then be conducted to verify the preconditions of the
hypotheses
Research work may be pure/basic research or applied research.
The ultimate purpose of basic research to advance knowledge, to make new
discoveries
The ultimate goal of applied research to find ways to improve the quality or
develop new types of commercial product
In general results of testing in research helps the scientist which route to fellow
next
Therefore, testing Is a means of determining the capability of an
item to meet specified requirements by subjecting the item to a set
of physical, chemical, environmental, or operating actions and
conditions
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9. Selection of samples
Textile materials show natural or intrinsic variations ,while measuring their
characteristics. Therefore to know the variation of population sampling is used
The sampling methods are governed to a large extent by factors such as:
1. the form of the material
2. amount of material available
3. the nature of the test
4. type of testing instrument
5. information required
6. degree of accuracy required
Statistical terminologies used for sampling are:
population –consists all the subjects that to be study
e.g. batch of cotton
Sampling –is the process of selecting a group of subjects in such a way that the
individual represent the large group from which they were selected
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10. Cont.…
Sample -a portion of a lot of material which is taken for testing
• Specimen a specific portion of a material or laboratory sample up on which test is
performed or w/c is selected for that purpose. E.g. taking 100 gms of cotton from 10 bales
selected from batch of cotton.
Fig.1 Relationship among production lot ,lot sample, laboratory sample and
specimens
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11. Cont.…
Materials taken from the lot sample for testing is laboratory sample
Sample size
Sampling techniques
There are several ways of sampling techniques
We look at four major types here:
• simple random sampling
• systematic sampling
• stratified sampling &
• cluster sampling
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12. A, Simple random sampling
Simple random sampling basic characteristics is that all members of the population have
equal and independent chance of being included in the sample
It is the most preferable method of sampling
Example 1- A garment factory manager wants to export 5000 T-shirts as per specification
he got from the customer and he wants to check the conformance of his product with his
customer specification after production of T-shirts . Here is how he did it:
I. the population is 5000 the batch of T-shirt
II. the desired sample size is 5% of or 250 T-shirts
III. then 250 T-shirts are randomly selected from 5000 T-shirts placed in organized way for
convenience accessing individual member of population
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13. B, Systematic sampling
 Systematic sampling is one in which every Kth subject on a list is selected for
inclusion in the sample.
 The “K” refers to sampling interval, and may be 3rd (K=3) or 10th (K=10) subject.
 The value of K is determined by dividing the population size by the sample size.
Example -2 :Let say that you have 36-meters of 1000 rolls fabric. If you decided to use
a sample size of 100,hence K=1000/100=10 ,then if you choose every 10th of roll of
fabric you will get a sample of 100.
C, Stratified Sampling(SS)
• SS permits the tester to identify sub-groups within a population and create a sample
w/c mirrors these sub-groups by randomly choosing subjects from each stratum
• Such a sample is more representative of the population across the sub-groups than a
simple random sample would be Sub- groups in the sample can either be of equal size
or proportional to the population size
• Equal size sample subgroups are formed by random selecting the same number of
subjects from each population subgroup
• Proportional sub-groups are formed by selecting subjects so that the sub-group
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14. Cont.….
Example 3: The following is a proportionally stratified sample:
i. population =9000 trousers
ii. the desired sample size is = 3%=270
iii. recording and leveling all 9000 trousers and classifying 9000 trousers
say:
• 65% -medium size (M) =5850
• 20% -small size (S) = 1800
• 15 % -large size (L) = 1350
• therefore 65 % of the sample = 176
20% of the sample = 54
15 % of the sample = 40
• Therefore, a sample of 270( 176+ 54+ 40) trousers, which is representative of the
9000 and which reflects proportionally each size category of trousers
• A non- proportionally stratified sample would randomly select 90 –trousers from
each sub-groups
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15. D, Cluster Sampling(CS)
• CS involves randomly selecting groups ,not individuals
• It is often impossible to obtain a list of individuals w/c make up target population,
any intact group with similar characteristics is a cluster
• There are draw backs to cluster sampling :
• First a sample made up of clusters may be less representative than one
selected through random sampling
• A 2nd draw back is that commonly used inferential statistics are not
appropriate for analyzing data from a study using cluster sampling .
Examples of cluster include : Classrooms in the college , schools, ,hospitals and
counseling centers in district.
Class activity
Let us a spinning general manager wants to test count of the yarns by taking the
samples from 1500 cones by using simple random sampling and systematic
sampling, so calculate number of samples to be taken by using random
sampling and Kth Value of systematic sampling.
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16. Atmospheric Conditions For Testing
Environment/Atmosphere as Variable
• Environment/atmosphere- here refers the medium surrounding a test specimen and
equipment use to carry out a test
• Some test are conducted under water or in the presence of gas other than air
• However, in the vast majority cases ,the atmosphere is air, either indoors or outdoors
• In the outdoor the atmosphere varies constantly, only in conditioned indoor spaces
the variation is more or less controlled
• The environment variations that weather forecasts talk about are:
• Barometric (air pressure)
• Temperature
• Humidity ,& sometimes pollution levels
• All these must be considered in outdoor tests on textiles, such as those for color
fastness to light and the effects of weathering-amounts of sunlight exposure
,cloudiness and rain also must be recorded
• Atmosphere indoors ,where most testing is performed do not vary as rapidly or as
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17. Temperature
• In practical terms ,only atmospheric temperature and humidity indoors have
much effect on textiles but that effect is quite complicated enough
• Temperature and humidity have an obvious influence on the characteristics and
properties of textile fibers. Under different temperature and humidity conditions,
textile test items, such as breaking strength, uniformity of strips, thread density,
pilling, static electricity, etc. will show different test results.
• Textile Fibers
• The molecules materials useful as textile fibers contain hundreds or thousands of
atoms
• Such molecules are much longer than water molecules
• Furthermore, all fiber forming molecules are long and thin ;w/c means that they can
be packed closely together
• Depending on manner of growth ,for natural fibers or manufacturing details for
manufactured fibers ,parts of the fiber structure will consist of perfectly arranged
crystalline regions (where portions or segment of many long molecules are parallel
and strongly held by intermolecular forces)
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18. Cont.…
• In these disordered regions (amorphous regions) intermolecular forces also bind
the fiber molecule together ,but the bonds are fewer in number ;the strength of
any one bond depends on both the distance it spans and the specific chemical
structures that give rise to the attracting force.
Glass Transition Temperature
• Intermolecular bonds are all that hold the molecules fiber together
• When a fiber is warmed up, the individual atoms and parts of the long molecules
vibrate back & forth more quickly b/n intermolecular bonds
• Warming has little effect on crystalline regions of the fiber because all the
intermolecular bonds are about the same strength and also relatively strong
• In disordered regions ,on the other hand each increase in temp. breaks more
very weak bonds once the energy of the motion reaches a threshold level
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19. Cont.…
• The whole fiber gradually becomes softer and more flexible as a result.
Consequently ,any fiber characteristic that is affected by intermolecular bonding
will be affected by change in temperature.
• Fiber properties affected by temperature are:
• Strength;
• Stiffness(hand & drape)
• Chemical reaction of fibers(chemical reaction speed up at high
temperature
• Stiffness (modulus)decreases slowly as temp.is raised ,except at threshold
temperatures where specific inter-atomic bonds become mobile, the rate of
change is greater.
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20. Temperature Control During Testing
• No single temperature can be fixed on as a standard temp. for all possible
circumstances
• If a material is being evaluated for use in extreme cold ,performing tests at one
or more very cold temperatures would make good sense ;
• The applies for tests related to a high –temperature to see its effect on some
characteristics(e.g. scorching in ironing) that temperature should be closely
controlled
• For the vast majority of textile tests a standard temperature of 20 oC is used
,because it is not possible even with very expensive air –conditioning equipment
,to control temperature exactly ,
• Good laboratory practice requires setting high and low limits . The standard
limits are : 20± 2 oC or equivalent degree fahrenheit temperature.
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21. Humidity
• Humidity- the amount of water vapor in the air
• The air picks moisture in the form of water vapor from rivers, lakes, wet ground,
trees and other plants & oceans
• Air losses moisture through precipitation
• The absolute humidity of an air mass is the actual weight of water vapor in a
cubic foot, cubic yard or cubic meter of air
• However there is a limit to the amount of water vapor that can be contained in a
volume of air ,and that limit changes rapidly with temperature
• Whether or not it will rain or snow and whether or not there will be fog, dew or
frost in the mooring depend not on the absolute humidity but on the relative
humidity (R.H.).
• R.H. –is the actual amount of water vapor in the air at given temperature
compared to the maximum limit the air can hold at that same temperature
• The effect of humidity on textile materials also depend on R.H. not absolute
humidity
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22. Cont.…
• The technical definitions of R.H. according to American Society for Testing &
materials(ASTM),reads: “the ratio of the pressure of water vapor present to the
pressure of saturated vapor at same temperature”
• The ratio is generally expressed as percentage or as decimal fraction
• Although this definition is more exact ,the one definition given previous ,gives the same
answer nearly to the boiling point of water and is easier to understand
Moisture Regain
• Most textile fibers hold a certain amount of water within their molecule structures
• This amount of water is commonly expressed as the regain ;or the percentage of water
by weight based on the dry weight of fiber
• In general moisture regain depends on:
• Chemical nature of fibers
• R.H.of air in contact with fibers
• If the R.H. of the air surrounding the fiber is changed the regain will change also, but
slowly over a period of time
• Most fiber characteristics are affected by the regain in the fiber at the time of
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23. Measuring Moisture Regain
• Moisture regain in textile material is usually measured by first drying the
material in an oven ,w/c should operated at temperature slightly above the
boiling point of water.
• Then the material is cooled to room temperature in a desiccators
• The weight of the material immediately after removal from the desiccators is
the oven dry weight
• Bone dry weight w/c could be obtained by drying at an even higher temperature
for a long time; however ,more intensive bone drying could damage the material
• The oven –dried textile material is then placed in air at known ,controlled R.H.
over time the material will gain weight by absorbing water vapor from the air.
At any time the moisture regain of the textile can be calculated:
MR(%)= (Wet weight –Oven dry weight ) x100
oven dry weight
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24. Cont.…
• Equilibrium Regain –ASTM defines moisture equilibrium as “ the condition
reached by a sample when it no longer takes up moisture from ,or gives up
moisture to the surrounding atmosphere
• Equilibrium is considered to have been reached if the change in the weight of the
material is less than 0.1% over a period of two hours provided that the material
has properly exposed to the air during that time
• Among the textile characteristics that change substantially as regain change
are:
• Strength
• Elastic recovery
• Electrical resistance
• Flammability
• Rigidity or stiffness
• Also actual weight of the material changes
• Fiber that do contain hydrogen bond forming
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25. Cont.…
• The hydrophilic fibers tend to reach moisture equilibrium slowly are also show
large change in other textile characteristics with change in R.H.
R. H. Controlled during test
• In some circumstances very higher or low relative humilities might be preferred
• Just as in a case of wrinkle recovery are sometimes carried out with the material
in equilibrium with air at 90% R.H. to simulate humid summer conditions, when
wrinkling might be most severe
• Measurement of both flammability and electrical conductivity (related to static
property ) are preferably performed at very low humilities at which the worst
performance can be expected.
Standard RH
• The standard RH chosen by consensus for the majority of test is 65 % ± 2% RH
Standard Regain
• Most commonly ,the regain of textile fibers in equilibrium with an atmosphere 65%
± 2% RH and 20 oC ± 2oC ,the standard atmosphere for testing textiles states as
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26. Textile Fiber Regain values at Standard conditions
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27. Electrical & Capacitance Methods for Measuring moisture
• The use of capacitance –based testers for measuring the moisture content of
textile materials is a quite old concept.
• The use of capacitance method for the determination of moisture requires control
of factors like fiber humidity ,temperature ,arrangement distribution of samples
in in the electrode and ratio of air –to- fiber in the textile
• Capacitance type measurement techniques provide accurate and sensitive tools to
measure many important properties of textile materials.
• Dielectric properties determine the static generation in textiles.
• Therefore, understanding the dielectric properties of textile materials is
important from the point of view of processing and quality control checking and
control
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28. Factors affecting the regain
• Different fibre types absorb different amounts of moisture depending on their
affinity for water as shown in Fig. 2.6 [6-1O]. For a given fibre type the moisture
content is governed by a number of factors:
• 1 Relative humidity. The higher the relative humidity of the atmosphere, the higher
is the regain of textile material which is exposed to it.
• 2 Time. Material that is in equilibrium at a particular relative humidity which is
then moved to an atmosphere with a different relative humidity takes a certain
amount of time to reach a new equilibrium. The time taken depends on the physical
form of the material and how easily the moisture can reach or escape from the
individual fibres. For example the British Standard for count testing [11] suggests a
period of one hour for yarn in hank form to reach equilibrium, but three hours for
yarn on packages.
• 3 Temperature. For practical purposes the temperature does not affect the regain
of a sample.
• 4 Previous history. The moisture content of textile materials in equilibrium with a
particular relative humidity depends on the previous history of the material. For
example the hysteresis effect as mentioned above means that it will have a
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29. Cont….
• Processing of the material can also change its regain value by altering its ability to
absorb moisture. The removal of oils, waxes and other impurities can also change
the regain by removing a barrier on the fibre surface to the flow of moisture
vapour. For example the standard regain value for scoured wool is 16% and that for
oil combed tops is 19%.
• Fig.A, Plot of regain versus relative humidity for viscose fibres fig.B,
Comparison of the moisture uptake of fibres.
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30. Textile fibers property
Cotton Fiber Properties
• The important cotton fiber properties in the spinning are:
Length & length uniformity
Short fiber content
Fineness or micronaire
Strength
Color
Trash
Neps
Maturity /Dye- ability
• These fiber properties vary in importance according to the spinning system in use
• Table below Ranks the importance of the various fiber properties for the four major
types of spinning systems in use today
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31. Cont.….
• Importance of various Fiber Properties for Different spinning technology
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32. Fiber Length
• Length is the most important property of a fibre. In general a longer average fibre
length is to be preferred because it confers a number of advantages such as:
I. longer fibres are easier to process.
II. More even yarns can be produced from them because there are less fibre ends
in a given length of yarn.
III. a higher strength yarn can be produced from them for the same level of twist.
• Alternatively a yarn of the same trength can be produced but with a lower level
of twist, thus giving a softer yarn.
• The length of natural fibres, like their fineness, is not constant but it has a range
of values even in samples taken from the same breed of animal or plant.
• Man-made fibres on the other hand can be cut during production to whatever
length is required with either all the fibres having the same length or with a
distribution of lengths.
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33. Cont.…
• Cotton is a comparatively short fibre with the finest variety, Sea Island cotton,
only reaching just over 50mm (2 in) in length, whereas some varieties of Indian
cotton may be less than 12mm (1
2 in) long.
• Wool is a much longer fibre than cotton and its length varies with the breed of
sheep. The length can vary in from about 375mm (15 in) long
• Mean length
• In the case of natural fibres the definition of mean length is not as
straightforward as it might at first seem. This is because natural fibres besides
varying in length also vary in diameter at the same time.
• If the fibres all had the same cross-section then there would be no difficulty in
calculating the mean fibre length.
• All that would be necessary would be to add up all the individual fibre lengths
and divide this sum by the number of fibres. However, if the fibres have different
diameters then the thicker fibres will have a greater mass so that there is a case
for taking the mass into account when calculating the mean length.
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34. Cont.….
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• Mean length of fibres.
• There are in fact three possible ways of deriving the mean length:
1 Mean length based on number of fibres (unbiased mean length) L.
2 Mean length based on fibre cross-section (cross-section biased mean length)
Hauteur H.
3 Mean length based on fibre mass (mass-biased mean length) Barbe B.

35. Cont…
• Fiber Length Measuring Instruments
• There are three well known instrumental methods of assessing cotton fiber length
,each quite different
i. The array method
ii. The fibrogram method (HVI)
iii. The AFIS method
• The array method - sorts a sampling of fibers by length and produces a category
by weighed distribution –staple diagram. This method is most commonly applied
using the Suter –Webb Array apparatus (Comb sorter )
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36. Cont.…
 The fibrogram method (HVI) – a different sampling simulates the way
those fibers will occur in the yarn making process by randomly catching
then along their length to produce “span length( the distance fibers
extend from their catch point), and then “arrays” the fiber segments
from shortest to longest .This method is used in Uster fibrograph and
HVI instruments
 The AFIS method – the AFIS method takes a sample and individualizes
the fibers, separating the fibers from the dust ,trash & neps in a
manner very similar to that of open-end spinning .Those individual fibers
are then sent through an air stream and pass an optical sensor w/c
measures each fibers length. The resulting number of distribution is
optically “weighted “to also produce by –weight staple diagram.
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37. Cont.…
The array method
The fiber sorter is an instrument which enables the sample to be fractionized in
to length groups.
Basically the operation involves four main steps:
i. The preparation of fringe or tuft with all the fibers aliened at one end
ii. The separation or withdrawal of fibers in order to decrease length
iii. The preparation of a sorter diagram by laying the fibers on black velvet in
decreasing order of the length, the fibers parallel and the lower ends aligned
along a horizontal base line
iv. The analysis of the diagram
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38. Cont.…
a) sample composed of parallel fibers aligned with one end laid out on the bed of
equidistant combs(pitch 2-4 mm for cotton,5-10mm for wool and 25mm for
vast fibers(see the above Figure)
 Respective distance b/n the teeth,0.5-1.3mm
 Sample is prepared by cutting a stretch of combed sliver and pressing it onto
one side of the bed of combs ,in a such way that one of the ends sticks out
in A.
 This end is “squared” (cut squaring method),eliminating short fibers(cut)
fibers., and then a group of fibers with aligned ends are removed and placed
on the right of the bed of combs in such a way that they are pressed into on
the opposite side B. The operation is repeated a number of times until a
sufficiently large layer is obtained
b)The combs started from A ,are lowered one by one until the tips of the longest
fibers are seen. Theses are then removed with tweezers and represent the first
class of length. The process is continued comb by comb for the other classes;
c)Placing the drawing (class of fibers) onto a table covered in black velvet to obtain
fiber diagram.
• In this method predetermined weight (grams) of fibers are sorted in to common
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39. Cont.…
• The velvet board shows the staple length distribution of the sample.
• Then ,beginning with the longest group each length group is weighed
• Weight data are used to calculate mean length and other length measurement
• Staple –length: “a quantity estimated by personnel judgment by which sample of
fibrous raw material is characterized as regards its technically most important fiber
length”
• Mean length- the average length of all fibers in the test specimen based on weight -
length data
• Effective length-is longer than the average length and is a measure of the length of
the majority longer fibers in the sample
• Span length –is the distance spanned by a specific percentage of the fibers in the
test beard ,taking the reading at the starting point of scanning as 100%
• The upper –Half –Mean Length(UHML)-is the average length by number of the
longest one –half the fibers when they divided on a weight basis
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40. Fibrograph Measures of length: The fibrogram
• Fibrogram –is a graph showing the length distribution of a sample of cotton fibers as
determined using the Fibrograph instrument
• The test specimen is a random selection of along their length from a “beard”.
• The beard simulates fiber arrangement during yarn production process, where fibers are
randomly overlapping and parallel (see Figure 3.3 )
• To understand the fibrogram concept ,consider fibers that are arranged in order of their
extension distances from the clamp(See Figure 3.4)
clamp extension
distance
Figure 3.3 Random arrangement in yarn making Figure 3.4
The fibrogram over lapping
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41. Reporting Measurements of Testing
• There are two different kinds of fibrograph length measurement : mean length
(ML) and span length(SL) as shown Figure below.
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42. Cont.…
• From these two different kinds of data, length uniformity is calculated .In order
to distinguish b/n the two ,one is called “ratio”(by using span lengths) and the
other is called “index”(by using mean lengths):
Uniformity Ratio = (50%SL÷2.5SL) x100
= (13.2÷28.5)x100
= 46.3%
Uniformity Index = (ML ÷ UHML )100
= (24.1 ÷ 28.7)x100
= 84 %
N.B. For normal cottons ,the uniformity ratio is in the 40% to 50% range and the
uniformity index is in the 75% to 85% range.
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Textile Testing 42

43. Fiber fineness and maturity
• Fiber Fineness: - fiber fineness can be expressed as the mass per unit length of a
fiber. fineness is important quality characteristic which plays a prominent part in
determining the spinning value of cottons. The fineness determines how many
fibers are present in the cross-section of a yarn of given thickness. Additional
fibers in the cross-section provide not only additional strength, but also a better
distribution in the yarn. Thirty fibers are needed at the minimum in the yarn
cross-section, but there are usually over 100.
• Fineness is generally expressed as gravimetric fineness or linear density (cell wall
area times a constant).
• Cotton maturity is a physical testing parameter of cotton fiber properties
testing. It is quantified by the degree of cell wall thickening relative to
its perimeters. The maturity of individual cotton fiber is an essential aspect of
the cotton classing regarding the aesthetics such as appearance, dye-uptake
etc. High volume instrument (HVI) can test cotton maturity like many other fiber
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Textile Testing 43

44. Fiber fineness
• Fineness is one of the most important properties of the fibres that are made into
textile products. The fibre fineness has a number of effects on the properties of
the yarn and hence the fabric that is made from it.
• The finer the fibre, the finer is the yarn that can be spun from it. As the yarn
becomes thinner, the number of fibres in its cross-section decreases and the yarn
becomes increasingly uneven because the presence or absence of a single fibre
has a greater effect on the yarn diameter.
• The spinning limit, that is the point at which the fibres can no longer be twisted
into a yarn, is reached earlier with a coarser fibre. Alternatively for a yarn of a
given linear density the use of a finer fibre will enable the production of a more
even yarn.
• . When staple fibres are twisted together into a yarn the twist provides the force
that holds the individual fibres together. Less twist is needed to make a yarn of a
given strength from fine fibres as the greater surface area which they possess
provides more cohesion
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Textile Testing 44

45. Cont.…
• The most important effect of fibre fineness is on the fibre stiffness. This is
because the rigidity of a fibre increases with the fourth power of the fibre
diameter so that a coarser fibre is a great deal stiffer.
• The stiffness of the fibres affects the stiffness of the fabric made from it and
hence the way it drapes and how soft it feels.
• Cotton fiber is a ribbon -like tube with a hole(lumen) in its center.
• Low micronaire fibers may cause neps in yarn & fabric.
• If they are mature, they may be strong; truly fine & very desirable. If however,
they are not mature, they may be weak and not desirable ultimately causing
yarn & fabric dyeing problems.
• Cotton fineness can be defined in various ways:
• Perimeter;
• Diameter;
• Area of cross-section;
• Mass-per unit length;
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Textile Testing 45

46. Fineness measurement
• When considering ways of measuring fibre fineness there are a number of factors
that need to be into account which make it difficult to define a measure of
fineness that taken is applicable to all fibres.
1) The cross-section of many types of fibres is not circular. Wool has an
approximately circular cross-section but silk has a triangular cross-section and
cotton is like a flattened tube. Man-made fibres are often made with trilobal,
star or hollow cross-sections for particular purposes. This makes it impossible to
have a universal system of fibre fineness based on fibre diameter.
2) The cross-sections of the fibres may not be uniform along the fibre length. This
is often the case with natural fibres.
3) The cross-sectional shape of the fibres may not be uniform from fibre to fibre.
Because of these problems a definition of fibre fineness is needed that can
allow for all the variations but that leads to a method of measurement which is
relatively simple to carry out. The great degree of variability found in natural
fibres means that a large number of measurements have to be carried out in
such cases.
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Textile Testing 46

47. Cont.…
There are a number of different ways of measuring fibre fineness/
diameter which differ fundamentally in their definitions of fineness
so that the measurements are not easily interconvertible. From
different ways of measurement of fineness of fibers let we can see
the following once's:
I. Gravimetric
II. projection microscope
III. airflow method
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48. Cont.….
I. Fiber fineness by Gravimetric
For a given fibre (that is of a fixed density) its mass is proportional to its cross-sectional
area:
Mass of a fibre = cross-sectional area X length X density
Therefore for a known length of fibre its mass will be directly related to its cross-sectional
area. This relationship is made use of in the gravimetric definition of fibre fineness in which
the mass of a given length of fibre is used as a measure of its fineness. This is similar to the
system of measuring yarn linear density.
The primary unit is tex (g/lOOOm), but it is also common to use: Decitex = mass in grams of
10,000 metres of fibre Millitex = mass in milligrams of 1000 metres of fibre Denier = mass in
grams of 9000 metres of fibre.
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49. Cont.….
• For fibres with a circular cross-section such as wool the mass per length can be
converted into an equivalent fibre diameter. By using the following equation:
Decitex = 106
= p * A
• where A = cross-sectional area in 𝑐𝑚2
p = density in 𝑔/𝑐𝑚3
See from the above tables for a list of common fibre
densities.
For a circular fibre then:
Decitex = 10−2
*p *
π𝑑2
4
where d = diameter of fibre in micrometres
This reduces to:
Decitex = 7.85 X 10−3
∗p*𝑑2
Similarly for denier:
Denier = 7.07 X 10−3 *p* 𝑑2
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Textile Testing 49

50. II, Fiber fineness by projection microscope
• The projection microscope is the standard method for measuring wool fibre
diameter, and all other methods have to be checked for accuracy against it.
The method is also applicable to any other fibres with a circular cross-
section. The method involves preparing a microscope slide of short lengths of
fibre which is then viewed using a microscope that projects an image of the
fibres onto a horizontal screen for ease of measurement.
Method of test
At first conditioning of the selected samples at standard atmosphere for 24
hours
Cut the fibres by using modified Hardy microtome to a suitable length
(0.4mm for fibres below 27 (μm) and a slide is prepared by carefully mixing
the fibres into the mountant.
The mounting agent should be non-swelling and have a suitable refractive
index (for example liquid paraffin). The mixture of fibres and mountant is
spread thinly on the slide and covered with a cover glass, carefully avoiding
air bubbles and finger prints.
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51. Cont.…
The slide is placed on the stage, cover glass down (microscope inverted) and
fibres are selected for measurement in the following way. The slide is
traversed in a zigzag fashion as shown in Fig. below measuring every fibre
that complies with the following requirements:
Fig. The projection microscope.
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52. Cont.…
1, has more than half its length visible in the 7.5cm circle which is
drawn in the center of the field of view;
2, is not in contact with any other fibre at the point of measurement.
The traverse of the slide is continued until the required number of
fibres has been measured. The magnification of the microscope is
adjusted to be 50Ox so that on the scale used to measure the fibres
each millimetre represents 2 μm.
For accurate tests three slides should be measured from randomly
selected areas of the material and not less than 150 fibres per slide
should be measured.
The coefficient of variation of diameter for unblended wool lies
between 20% and 28%.
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Textile Testing 52

53. III, Fibre fineness by the airflow method
Surface area can be expressed as area per unit volume ( or specific surface) and
be estimated with air flow instrument
From basic fluid flow theory, it can be shown that the air permeability of a test
specimen of a specified mass in a chamber of specified dimension is related
to the fiber surface area
Micronaire value is a measured cotton fiber quality which is an indication of the
fiber specific surface area. The micronaire value is a function of both fiber
fineness and maturity. Low values indicate fine and/or immature fibers ; high
values indicate course and/or mature fibers.
fig. cross-section of
cotton fiber
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54. Cont.…
The micronaire value ranges from about 2.0 to 6.0
i. Below 2.9- very fine :possible small perimeter but mature (good fiber) or
large perimeter but immature (bad fiber)
ii. 3.0- 3.7 -fine : Various degree of maturity and perimeter
iii. 3.8- 4.6 -average : average degree of maturity and /or perimeter
iv. 4.7- 5.5 – course : usually fully developed (mature) but large perimeter
v. 5.6+ very course : fully developed ,large perimeter fiber
Micronaire
The micronaire tester is the most widely used instrument to measure surface
area of fibers or cotton fineness ,which was introduced in 1964,and consists of an
air gauge to measure air flow through a cotton sample of specified weight w/c is
placed in a chamber of fixed dimension
The mocronaire “scale” was originally calibrated by using the measured linear
density of group of test cottons
The instrument readings were assumed to indicate gravimetric fineness in
micrograms /inch
An air compressor supplies air to the instrument via the foot-operated valve ,the
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Textile Testing 54

55. Cont.…
Figure Air circuit for Sheffield micronaire
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56. Cont.…
A special master plug is pushed home in to the fiber compression chamber .
The instrument is then adjusted so that the float in the flow- meter tube rises to
an upper limit, with air flowing through the plug, and to a lower limit ,when the
flow of air is restricted by placing the thumb over a hole in the top face of the
plug.
The adjustment are made by the float positioning knob and the calibration screw.
When this initial adjustment is completed the master plug is removed and the
instrument is ready to test the samples.
Test Procedure
i. Weigh the sample of 50 gr (3.24gr) with good quality balance. An accuracy of
± .1 gr
ii. Work the sample into a fluffy mass with the fingers to thoroughly randomize
the fibers, eliminating, all knotty balls & stringy sections of the fiber
iii. Place the sample in in the fiber compression chamber
iv. Insert the fiber compression plunger and lock in to place by twisting. This
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Textile Testing 56

57. Cont.…
v. Step on the foot pedal to run on air and take the scale reading to the
nearest 0.1 scale unit at the point
level with the top of the float
vi. Step on the foot pedal to shut off the air ,remove the fiber compression
plunger and again step on the foot pedal. The sample will be blown out of
the compression chamber
vii. Before inserting another sample, operate the foot pedal to shut off the air
supply
viii.It is recommended that at least two samples be chosen and weighed from
test lot
Experience on broader ranges of samples showed that the scale did not
represent gravimetric fineness. Fiber surface area is the property measured by
the instrument ,and early scientists recognizing that the instrument did not
truly measure micrograms per inch named the instrument “micronaire”.
Although micromere is not literally fineness ,it is recognized by many to be a
very important measurement for establishing the value of cotton & criteria for
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58. Maturity Testing
• Cotton maturity is the ratio of wall area divided by perimeter squared.
• Fiber maturity is an important character of cotton and is an index of developments of
the fibers
• The maturity of the cotton fibers varies not only between fibers of different samples but
also between fibers on the same seed. Thus a ripened full mature cotton boll contain
fibers of both mature and immature.
• A cotton fiber consists of a cuticle, a primary wall and secondary wall of cellulose
surrounding the lumen or the central canal.
• In the case of mature fiber, the secondary wall thickening is very high and in some cases,
the lumen is not visible(see figures ( A & B)
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59. cont.…
• In the case of immature fibers, due to some physiological causes, the secondary
wall thickening is practically absent, leaving a wide lumen throughout the fiber.
• Hence to a cotton breeder, the presence of excessive immature fibers in a
sample would indicate some defect in plant growth, either varietal or
environmental.
• To a technologist the presence of excessive percentage of immature fibers in a
sample is undesirable as this causes waste, losses in processing, lowering of the
yarn appearance grade due to formation of neps, uneven dyeing etc.
• The determination of the fineness of cotton is affected by maturity of the
sample.
• An immature fiber will show a lower weight per unit length than mature fiber of
the same cotton, as the immature fiber will have less deposition of the cellulose
inside the fiber.
• Hence it is essential to measure the maturity of a cotton sample in addition to
the determination of its fineness., to check whether the observed fineness is an
inherent varietal characteristic or is a result of immaturity.
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60. cont.…
• The maturity of the fiber is concerned with development of cell wall. The cell
wall thickening is highly sensitive to growing conditions. Adverse weather, poor
soil plant, plant diseases and pests etc., will increase the proportion of
immature fiber and lead to trouble in processing.
• Troubles caused by the presence of these thin walled immature fibers are :
• Nepping - causes like small bits or fragments of seed particles attached to the
fiber forms neps:
• Neps are created during processing starting at ginning stage.
• Further when rubbing of substances takes place, as in carding, minute knots
of tangled fibers are caused and the immature fibers are more prone to this
nepping effect.
• When fine cottons are being processed, the danger of nepping is even more
acute, since even the mature fibers are likely to cause neps by faulty
processing. In addition, the neps so formed are usually more prominent
because of their size relative to the diameter of the yarn
• The presence of neps in a yarn will also form weak places and therefore the
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61. cont.…
• Immaturity also affects the shade after dyeing.
• As the response of the primary wall to certain classes of dyestuffs is less
intense, the thinner the secondary wall lighter will be shade.
• Hence fine cotton tends to be lighter in shade than coarse cotton.
• Apart from this the reflecting surfaces of the fibers of immaturity is with
respect to the patches being shown or the weft bars seen in the fabric when
yarn made of immature fibers or yarn spun from cotton of different maturity is
used as warp and weft
• So summarizing the maturity, the following points are noted.
i. Maturity affects the quality of the yarn and its processing. The effect of the
immature fibers are seen especially in the spinning process.
ii. The large number of ends downs in a ring frame is due to the immature
fibers.
iii. The loss in yarn strength, the dyeing troubles are all due to the presence of
immature fibers.
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62. Methods of Determination of Maturity
• Several methods are available to determine the maturity of cotton. These can be
grouped as below:
1. Direct method - caustic soda swelling method
2. Indirect method
i. Differential dyeing method
ii. Caustic aire method
iii. Polarized light method.
Direct method- Caustic soda swelling method
• It is the most commonly used method. A thin tuft of fibers is drawn by means
of tweezers from a silver held in a comb sorter. The tuft is laid on a microscope
slide., the fibers parallel and separated and a cover slip is put over the middle.
Likewise four to eight slides are prepared. There are two steps involved in this
method.
1. Treatment with 18% caustic soda.
2. Examination under a microscope to count the mature, half mature and
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63. Maturity Testing
• The fibers on the microscope slide are then irrigated with a small amount of 18%
caustic soda solution, which has the effect of swelling them.
• The slide is then placed on the stage of a microscope and examined. The
presence or absence of the convolution is observed and the fibers are classified
into three groups.
i. Mature or normal fibers.
ii. Half mature or thin walled fibers.
iii. Immature or dead fibers.
• The presence of caustic soda changes the appearance of both mature and
immature fibers by swelling.
• Mature fibers with a well developed cell wall and pronounced convolutions in the
raw state become rod like swelling. These rod like fibers are classified as
normal or mature fibers.
• In the case, the lumen is practically absent. Dead or immature fiber appear
ribbon like even after swelling. In dead fibers, the wall thickness is less than
1/5th of the ribbon width.
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64. Cont.…
• The fibers are classed as above based on the ratio of lumen width (L) to wall
thickness (W) as indicated below:
Class Ratio of lumen width to wall thickness ( L / W )
Mature Less than 1
Half mature 1 - 2
Immature Greater than 2
• All the slides are examined as above and the percentage of mature ( N ) half
mature ( H ) and the immature ( I ) fibers are calculated. Then the maturity of
the cotton fiber is expressed by any one of the following terms:
i. Percentage of mature fibers, N
ii. Maturity Ratio ,M
iii. Maturity Coefficient ,Mc
• Knowing the total number of fibers examined and the number of mature fibers the
percentage of mature fibers can be calculated as below:
Percentage of maturity
Percentage of Mature fibers = Number of mature fibers x 100
Total number of fibers examined
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65. Cont.…
Maturity Ratio M
• The percentage of the three classes of fibers are combined into a single index termed
the maturity ratio and is approximately proportional to the degree of cell wall
thickening. i.e. Degree of cell wall thickening ø = 0.577M
• Maturity ratio is calculated using the following equation:
M = (N - D) + 0.7
200
where N = Percentage of normal fibers
D = Percentage of immature fibers
• The theoretical value of M will vary from 0.2 for all dead fibers to 1 and very rarely
more than one for too mature fibers and can cause problem in the spinning process.
• It can also be calculated from the actual fiber weight per cm H and the standard fiber
weight per cm.Hs by the relation.
M= H/Hs
• The standard fiber weight per cm, also called as intrinsic fineness is that which the
fiber would have fully matured in the arbitrary sense of having an N-D of 60.
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66. Cont.…
Maturity coefficient Mc: (Maturity count)
• The fiber maturity count is denoted by the percentages of the mature, half mature and
immature fibers in a sample. It can be calculated using the formula,
Mc = (N + 0.6H + 0.4I)/100
where N - percentage of mature fibers.
H - Percentage half mature fibers
I - Percentage of immature fibers
• For the chosen standard, N = 67% D or I = 7% and H = 26%.
Mc = ( 67 + 0.6(26) + 0.4(7) )/100 =0.85
• Based on the maturity coefficient, the cottons are classed into different groups as
shown below:
Maturity Coefficient Rating
Below 0.06 Very immature
0.60 to 0.70 Immature
0.71 to 0.80 Average maturity
0.81 to 0.85 Good maturity
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Textile Testing 66

67. Fiber Strength
• The fact that strong yarn cannot be made from weak fibers confirms that the strength
is very important parameter for evaluating cotton for use in spinning & fabric
formation
• The textile industry requires strong cotton fiber for high –speed modern textile
operations.
• Strong fibers can be span at higher speeds ,thus improving the economics of yarn
formation as stronger fibers can offset the resistance losses of yarn obtained from
high speed
• Fiber strength started to be routinely measured when the Pressley strength tester was
developed over 60 years ago.
Structure of Cotton Fiber
• For cotton strength consider, the fiber to be constructed similar are to steel –link
chain.
• Somewhere along the chain will be a week link.
• Regardless of genetic variety ,there is a week place with every 1/8 inch(3.2mm)
distance along cotton fibers(see fig. a)
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68. Cont…
• When there is no space between clamps(zero-gauge ) as shown in Fig. b the probability
that the fiber will break at a weak places is extremely low.
• True strength will not revealed ,the test will almost always indicate a strength higher
than the actual strength
• But when there is a 1/8 inch space between clamps (1/8 inch gauge ) as shown in fig. b
cotton will always break at weak places ,revealing the true length of fibers.
Fig. a. Weak place within every 3.2 mm distance length of cotton fiber
Fig. b Zero gauge
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69. 69
Textile Testing
• However, it is still not known if weak links are genetically controlled ,or if weather
influences their occurrence
• The 3.2 mm gauge fiber strength value better correlates with yarn strength .Most
countries have changed ,but zero gauge information is still used in some countries.
• The most common methods of determining fiber strength using “bundle” method are :
i. Pressley tester;
ii. Stalometer;
iii. HVI strength tester
• The extended use of rapid instrument testing machines in the world has forced the cotton
industry to use Stalometer 3.2 gauge readings; because data from Pressley measurements
could not be converted in to value equivalent to 3.2 gauge by general formula for all
verities
• The fundamental difference b/n Stalometer data and the HIV data lies in the data are
recorded
• The stalometer gives a basic strength value that provides bundle fiber breakage following
the rules of constant load . After the fiber bundle breaks the actual sample weight is used
to determine the strength value .The instrument gives bundle strength and elongation
Cont.…
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70. Cont.…
• The HVI system does not allow measurement of fiber bundle weight at the time of fiber
breakage and therefore ,HVI needs cotton standards with known strength and micronaire
values for comparison purpose .
• This mean that the HVI strength measurement is an indirect measurement of a value by
comparison with standard sample
• The stalometer readings are generally lower than HVI readings for strength
• There is no exact conversion factor ,but Stalometer readings can be multiplied by 1.28
in order to have an estimated HVI equivalent value
• Pressley machines are the oldest , however they are still working because their handling
does not require much sophistication
 Measurement of bundle strength hides the low values of weaker fibers .Bundle strength
is influenced by the length of single fibers ,because of this ,and also other reasons
,there is need to measure the strength of single fibers
• Single fiber testing used to breeders and researchers with limited testing material
available
• There are various classes of dynamometers for individual fiber length measurements.
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71. Cont.…
• The WIRA Single Fiber Strength Meter See Fig. c deserves special attention .
• This was developed to simplify to the utmost the manipulation of the fibers enables up
to 500 measurements an hour to be performed on wool
• The principle characteristic consists of a special type of electromagnetic clamp and in
the fact the specimen length required is automatically determined as each fiber is
removed from the mass of fibers of which the specimen is composed
Fig. c WIRA single fiber strength testing machine
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Textile Testing 71

72. Cont.…
• Cotton fiber is usually tested in bulk from utilizing a mass or tuft of fibers to be
presented to a test instrument for measurement .
• There are many reasons for this ,not the least of which is that handling single
cotton is tedious and time consuming.
Single fibre strength
• Tests on single fibres can be carried out on a universal tensile tester if a suitably
sensitive load cell is available. Also required are lightweight clamps that are
delicate enough to hold fibres whose diameters may be as low as
• 10-20 ^m.
Figure 5.20
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Textile Testing 72

73. Cont.…
• A problem encountered when testing high-strength fibres is that of gripping the
fibres tightly enough so that they do not slip without causing jaw breaks due to
fibre damage. If the fibres cannot be gripped directly in the testing machine
jaws they are often cemented into individual cardboard frames which are
themselves then gripped by the jaws. The cardboard frames, shown in Fig. 5.20,
have an opening the size of the gauge length required. When they are loaded
into the tensile tester the sides of the frame are cut away leaving the fibre
between the jaws. The cement used is responsible for gripping the fibres,
therefore the samples have to be left for a sufficient time in the frames for the
cement to set.
• The US standard for single fibre strength [11] specifies a gauge length of either
jin or 1 in (12.7 or 25.4mm). Up to 40 fibres should be tested depending on the
variability of the results. The elongation rate depends on the expected breaking
elongation With fibres that have crimp a pretension of 0.3-1 gf/tex (2.9 to 9.81
mN/tex) can be used to remove the crimp.
• under 8% 10% of initial specimen length/min
• 8-100% 60% of initial specimen length/min
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Textile Testing 73

74. Cont.…
• The British standard specifies gauge lengths of 10, 20 or 50mm with a testing
speed adjusted so that the sample breaks in either 20 or 30s. The number of
tests is 50 and the level of pretension is set at 0.5 gf/tex (4.9 mN/tex).
• Bundle strength
• Pressley fibre bundle tester
• The Pressley tester is an instrument for measuring the strength of a bundle of
cotton fibres. Before they are mounted in the instrument the cotton fibres are
combed parallel using a hand comb into a flat bundle about 6mm wide. The
special leather-faced clamps are removed from the machine and placed in a
mounting vice so that they lie adjacent to each other, thus giving zero specimen
length. The bundle is placed across the two jaws and clamped in position by the
top jaws. When the clamps are removed from the mounting device the fringe of
fibres protruding from the outer edges of the clamps is trimmed off leaving a
known length of fibre within the jaws.
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75. Cont.…
• When the jaws are loaded into the instrument the upper jaw of the pair is linked
to the short arm of a pivoted beam. The longer arm of the beam is inclined at a
small angle to the horizontal and has a weight on it which can roll down the
slope.
• As the weight moves away from the pivot the force on the top jaw gradually
increases until the bundle breaks. When this happens the moving weight is
automatically halted so that the distance along the arm can be measured. As the
distance from the pivot is proportional to the force on the fiber bundle, The arm
can be directly calibrated in units of force (lbf).
• At the end of the test the two halves of the bundle are weighed, and as the total
length of the bundle is fixed a figure of merit known as the Pressley Index can be
calculated:
• Pressley index (PI) =
𝑏𝑟𝑒𝑎𝑘𝑖𝑛𝑔 𝑙𝑜𝑎𝑑 𝑖𝑛 𝑝𝑜𝑢𝑛𝑑
𝑏𝑢𝑛𝑑𝑙𝑒 𝑤𝑒𝑖𝑔ℎ𝑡 𝑖𝑛 𝑚𝑖𝑙𝑖𝑔𝑟𝑎𝑚
• The result can be expressed as gram force per tex by multiplying the index by
5.36 or in mN per tex by multiplying by 52.58. Because the gauge length in this
test is zero the extension of the fibres cannot be measured.
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76. Cont.….
• Stelometer
The Stelometer is a bundle testing instrument which is capable of measuring
elongation as well as strength. The instrument uses the same type of jaws as the
Pressley instrument but they have a separation of 3.2mm (|in) as distinct from
the zero separation of the Pressley instrument.
The loading of the specimen is carried out by a pendulum system which is
mounted in such a way that it rotates about its center of gravity. This eliminates
any inertial effects in loading of the sample which is generally a problem with
systems that apply the force using a pendulum. The layout of the instrument is
shown in Fig. 5.21: the pendulum is pivoted from the beam but the pivot of the
beam is at the center of gravity of the pendulum.
The sample is held between the clamp attached to the beam and the one
attached to the pendulum. The beam and the pendulum start in a vertical
position but the center of gravity of the beam is such that when it is released at
the start of the test the whole assembly rotates.
 As the beam rotates the pendulum moves from the vertical so that it then exerts
a force on the sample. The speed of rotation of the beam is altered by dashpot so
that the rate of loading is 1 kgf/s. A pointer is moved along a scale graduated in
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77. Cont.….
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78. Cont.….
• After breaking the bundle all the fibres are weighed allowing the tenacity to be
calculated:
Tenacity in gf/tex =
𝑏𝑟𝑒𝑎𝑘𝑖𝑛𝑔 𝑓𝑜𝑟𝑐𝑒 𝑖𝑛 𝐾𝑔𝑓 ∗15
𝑠𝑎𝑚𝑝𝑙𝑒 𝑚𝑎𝑠𝑠 𝑖𝑛 𝑚𝑖𝑙𝑖𝑔𝑟𝑎𝑚
• The effective total length of the sample is 15mm (0.590in) for a -|in (3.2mm)
gauge length and 11.81mm (0.465 in) for a zero gauge length so that 11.8 should
be used in the above formula if a zero gauge length is used.
• The tenacity measured at zero length is greater than that measured at ^ in length
because of the general effect that shorter gauge lengths have on measured
strength. The ratio between the two values will vary with the variability of the
material being tested.
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79. Trash Content Testing
• Trash is important criteria for classification of cotton. High trash means lower
grade and lower price with other things equal
• Bolls on plants have no trash or non-lint contamination. But when a boll opens ,it is
vulnerable to being contaminated by dry leaves and other plant parts
• Hand picked cotton is expected to carry less plant material ,while machine picked
seed cotton may contain up to 1/4th of non-lint material
• Trash particles other than leaf are collectively called “extraneous matter” in
cotton classing system
• With visual evaluation of trash content ,seven physical standards are used by the
USDA to determine leaf grades designated “1” through “7”
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80. Cont.…
• Different trash categories have different influences on the textile processing of
cotton and the quality of finished products.
• Breakage during spinning is the biggest concern regarding trash, and statistics show
that the breakage increases by approximately 60% with a 1% increase in bark
content
• Hence cotton must be cleaned during ginning ,however, excessive cleaning also
damages cotton quality.
• Technique that are currently available for the identification of trash in cotton
include:
i. Shirley Analyzer
ii. Advanced Fiber Information System (AFIS)&
iii. HVI
• The Shirley Analyzer measures the total amount of trash present in cotton sample.
• Trash measurements from AFIS include the percent content of foreign matter or
visible foreign matter (dust & trash)
• The measurement is by an optical sensor and categorizes the trash objects in
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81. Cont.….
• The HVI system measures trash or non-lint content by use of Video-camera to
determine the amount of surface area of the sample that is covered with dark
spots.
• The video signal is processed by a microcomputer to determine the number of
dark spots encountered (count )& the percent of the surface area covered by
dark spots(area)
• The area and count data are used in an equation to predict the amount of
visible non-lint content as measured on the Shirley Analyzer
• However, the HVI measurement does not typically present the size and the
type of trash particles found in a sample.
• Currently no commercial techniques are available that can be accurately
used in the cotton industry to measure and categorize trash
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82. Data Analysis Using HVI & AFIS
1 HVI
• The fiber characteristics are very important for yarn production, the sample size
for testing fiber characteristics is not big enough. This is due the following :
• The labor & time involvement for testing of a representative was to expensive
• The results were often available too late to take corrective action
• The results often depended on the operator and/or the instrument and could
therefore not be considered objective
• Administration of raw material data
• The USTER HVI 900 system measures 7 physical characteristics defined by the
United States Department of Agriculture (USDA) in its cotton marketing system.
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83. Cont.…
• The HVI 900 system measures :
• Fiber length;
• Strength;
• Length uniformity;
• Uniformity;
• Elongation;
• Micronaire ;
• Color & Trash
• The HVI 900 fiber testing system offers precise and reliable automated
operation with computer controlled calibration and diagnostics
• All functions are controlled by dedicated microprocessors to simply operation
& provide flexibility in testing parameters
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84. Cont.…
• The system may include any combination of the following modules:
• Length/strength module
• Micronaire module
• Color/trash module
• The HVI system exist in semi –automatic and automatic forms. The main
difference b/n the two systems are : in length /strength module, that is in
sample preparation, w/c is the same in principle but is automated in
preparation on the 900 automatic
• Testing cotton samples using HVI may give variation due the following reasons:
• Natural variation in cotton
• Calibration cottons
• Variation in ambient RH & Temperature
• Operator influence
• Instrument variation (due to improper maintenance ,or operation)
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85. Cont.…
• The HVI 900 system is a series of test devices connected to an internal computer w/c
collect data as samples are measured ,in series ,by one test then another
• Using 1-2 operators measurements and corresponding calculations are made at rate
about 30 seconds for one test per sample
• The following are measurements and calculations provided by the USTER HVI 900 :
• Length
• Length uniformity
• Strength
• Elongation
• Micronaire
• Color grade
• Trash code
• Short fiber index
• Spinning consistency index(SCI)
• Count strength product (CSP)
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86. Cont.…
• Short fibers for cotton are defined as all fibers les than ½ inch or 12.7mm
• Spinning Consistency Index (SCI)-an index w/c indicates the spinnability of a
bale of cotton ,based on formula ,incorporating all HVI results
• Count strength product (CSP)-An index w/c indicates the predicated yarn
breaking strength based on formula including all HVI data results
Advantages of HVI
• The results are practically independent of the operator
• The results are based on large volume samples ,and are therefore
significant
• The respective fiber data are immediately available
• The are clearly arranged in summarized report
• They make possible the best utilization raw material data
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87. Advanced Fiber Information System (AFIS)
• The AFIS method is based on aero-mechanical fiber processing ,similar to
opening and carding ,followed by electro-optical sensing and then by high
speed microprocessor –based computing and reporting.
• A fiber sample is introduced into the system, and is processed through a fiber
individualizer w/c aero- mechanically separates the sample into three
component consisting of cleaned fiber ,micro- dust, and trash
• Each of these components is transported in a separate
pneumatic path and may be analyzed electro-optically or by other means
• The data are processing and reporting are handled by an individualized PC
• AFIS provides basic single fiber information and is distinguished from earlier
and existing methods by providing distributions of the basic fiber properties.
• These distribution measurements provide more accurate precise and basic
information about fiber.
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Textile Testing 87

88. Winners do not do different things. They just do same
thing differently!!!!
Work smart not hard to be a successful person in your
life!!
Thank you!!!!
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Textile Testing 88