This document discusses cotton fiber length, including factors that affect it, methods to measure it, and its influence on yarn and fabric properties. It describes how cotton length is determined by genetics and affected by environmental conditions. Methods to measure length include direct measurement of single fibers or preparing fiber bundles. Longer fibers contribute to stronger yarns and fabrics with better uniformity, less hairiness, and improved handle and luster. Shorter fibers increase processing waste and yield weaker, less even yarns.

1. SEMINAR TITLE: COTTON LENGTH
INCLUDES:-FACTORS AFFECTING IT
–METHODS OF MEASURING IT
-ITS INFLUENCE ON YARN AND FABRIC
BY GROUP-I MEMBERS JUNE 2019
HAWASSA,ETHIOPIA
Department of Textile and Garment engineering
Textile Testing-I Seminar

2. Group one
membersR.NO Name ID
I Meklamu Kenito TECH/0750/09
II Mihret Pawlos TECH/1823/09
III Biniyam Negash TECH/0555/09
IV Natnael Tesfaye TECH/0409/09
V Dagmawit Kebede TECH/1416/09
VI Endale Bogale TECH/1119/09
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3. DBB
Table of contents
R.No Title Slide
I Introduction 4
II Factors affecting cotton length 7
III Methods of measuring cotton length 14
IV Influence of cotton length on property of yarn and
fabric
30
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4. Introduction:
 Cotton is the shortest commercial textile
fiber
 length is a genetic trait and varies
considerably across different cotton species
and varieties.
 Cotton fiber length is probably the most
significant fiber property because it
directly affects irregularity of fiber
assemblies.
 longer lengths contribute to the tenacity of
yarn via increased frictional forces with
adjacent fibers.
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5. Introduction
 The presence of short fiber in cotton causes
appreciable increases in processing wastes,
excessively uneven fiber assemblies, less
efficient spinning, and weaker yarns
 Historically, fiber length is measured in inches
although conversion into millimeters is now
common.
 Fiber length is defined usually as the upper-half
mean length (UHML) or 2.5% span length
(2.5%SL) from a Fibro-gram beard.
 Both measures coincide in a roundabout way
with the classer’s staple.
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6. Introduction
 Length and length distribution are also
affected by agronomic and environmental
factors during fiber development.
 These effect may lead to variation in cotton
fibers of the same type.
 This material covers the factors that can
affect cotton length, the ways to measure it
and its influence on the quality or property
of yarns and then fabric produced from it.
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7. Factors that can affect cotton
length:
geology of the cultivation area
 soil constitution
weather conditions during the maturing
period
cultivation technique
mechanical processes at and after harvest
the region of the cotton-seed that the
fiber is taken from.
temperature, water supply and light
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8. Length of cotton
Length is not constant for natural fibers
as their fineness do unlike manmade
fibers.
 For natural fibers:
Even fibers taken from the same breed of
animal or plant can have different length.
 For manmade fibers:
They can be cut at whatever length is
needed or length is controllable that can be
made uniform
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9. Length of cotton
Length of cotton can be
I-staple length
II-mean length
Staple length:
 is an average length of spinnable fiber
 Fibers can be categorized as follow based
on its staple length
~Short(1 in or less)
~Medium(1.03-1.125 in)
~ Long(1.16-1.38 in)
~Extra long(1.9 in and above)
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10. Continued…
Mean length:
 is an average of length of given fibers
 the definition can not be applied to the natural
fibers with it’s original sense for natural fibers
vary in length and diameter at the same time.
 to add two things they have to be of the same
quality.
 due to the variation in natural fibers we can’t
add them (for the thicker weights more).
 then we need to have a system that takes
weight under consideration and calculate the
mean length.
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11. Mean length
 For three fibers of length l1 ,l2 and l3,cross
sectional area of al, a2 and a3,weight w1 w2
and w3.
It Can be derived in one of the three systems
Mean length based on number of fibers(L)
 Doesn’t consider the effect of mass and
diameter, just number of fibers.
 Is given by
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12. Continued…
Mean length based on fiber cross section(H)
 Weighting each fiber according to its
cross section.
 Is given by
 For data from comb sorter H can be
calculated by dividing mass of each length
group to its length and expressing the
value as a percentage
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13. Continued…
Mean length based on fiber mass (B)
 Mass of each length group in comb sorter
method is weighted and the average
length is calculated from the data.
 Is given by
 We can substitute w=lxa in to the above
formula for constant density and find the
new one.
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14. Methods Of Measuring Cotton
Length
 The methods used to measure fiber length fall
into two main types:
I. the direct measurement of single fibers mainly
for research purposes
II. methods that involve preparing a tuft or bundle
of fibers arranged parallel to one another.
 When we measure length large number of fibers
has to be involved in the measurement to get
statically accurate value.
 Then any method employed to measure and need
individual fiber handling is time consuming leading
to less fiber involvement in the measurement.
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15. Direct methods
I-By hand:
 The simplest direct way of measuring
single fibers.
In the method:
 Each end of the fiber is grasped by a
pair of tweezers and the fiber
stretched alongside a rule.
 Tension applied while grasping has to be
applied until the whole crimp is removed
and doesn’t go beyond that.
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16. …By hand…continued…
 To control that weight can be hung on at
end of the fiber.
 Then the length is measured.
 The method is still slower.
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17. II-Comb sorter method
Terms to be used:
Short fiber percent
-is the percent of fibers shorter than 0.5 inch.
-denoted by SFC or SFP
Effective length
-is average of length of fibers within a material
with which most of machine setting is adjusted.
Floating fiber index
-Is an indication to the fibers that are not
clamped by either pair of rollers in drafting
region
-denoted by FFI
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18. Terms…continued…
Span length
- Span length is the distance exceeded
by a stated percentage of fibers from a
random catch point in drafting zone.
- 2.5% and 50% span length are the most
commonly used by industry
- Denoted by SL
Uniformity ratio
- The ratio between 50% to 2.5% span
length
- Denoted by UR
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19. Comb sorter diagram
Dimensional relation in the diagram is given
as follow
OQ = 1/2 OA OK = 1/4 OP
KS = 1/2 KK’ OL = 1/4 OR
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20. From the diagram
SFP=(RB/OB) × 100%
Inter-quartile range(IQR)
LL’-MM’ = NL’
Dispersion%
-is percent of the ratio between
effective length(LL’) and IQR(NL’).
= ( NL’/LL’) ×100
(comb sorter diagram analysis remain unanswered)
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21. III-single fiber measurement
 Each fibers are taken separately and
gently over the slide.
 Then the length is recorded.
 The system is tedious and time
consuming .
 Used where number of fiber is smaller.
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22. IV-length measurement by
weighting system
 Combing
 Then placing the fiber on the velvet pad
 Grouped In to length groups with group
length range of 0.125 inch
 Weighting each group with certain sensitive
device.
 Then mean length is evaluated with
mathematical expression.
 Mean length evaluation
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23. V-clamped tuft method
(weighting method)
 Clamping
 Combing to remove loosely held fibers
 Protruding tufts are cut at an edge of
clamp and weighted.
 The clamp then open and fibers inside
the clamp are weighted separately
 Then length evaluation
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24. clamped tuft method…continued…
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25. VI-Shirley photoelectric stapler
 Fringe of fibers is prepared by hand and carefully placed
over black velvet pad
 Photoelectric stapler detects the distance between
where density gradient is maximum( in each side)
 Two photoelectric cells are connected opposite to each
other
 Depending on light intensity, opposed cells pass current
which is proportional to intensity difference
 Variation in current is displayed on sensitive
galvanometer
 As the fringe is advanced inside the instrument, two
maximum density gradient point will be there and this
distance is ‘’staple length’’(maximum deflection of
galvanometer in opposite direction.
E.L=P.E. staple length x 1.1
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26. Shirley photoelectric stapler
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27. VII-photoelectric method
 Optical method of measuring density along
the length of tuft of parallel fibers
 The sample is made with ‘’fibro-sampler’’
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28. Assumptions in the system
I. Fiber is caught on the comb in
proportion to its length .
II. The point where it caught is random
along its length.
Floating fibers
= {(2.5% SL)/(L-0.975)}x 100%
Uniformity ratio
=(50% SL)/(2.5 SL)
Where L-is mean length of fiber
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29. Continued…
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30. Influence of cotton length on
yarn/fabric:
The fiber length categorized under one of
the three most important characteristics
of cotton can have an influence on one or
more of the following yarn/fabric
characteristics:
 Yarn strength
 Yarn evenness
 Yarn hairiness
 Handle of the product
 Luster of fabric
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31. How can length influence those
properties?
Yarn strength:
o The shorter the fiber the lower will be its
contribution to yarn strength.
For example: fiber of length with in the
range of 12-15 mm do not contribute much to
the strength of yarn.
 The yarn made from shorter fibers is
weaker than yarn made from longer fibers
of the same quality.
 Then the weaker the yarn the weaker will
be the fabric made from it.
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32. How…?continued…
Yarn evenness:
The longer the fiber the lower will be the
number of fiber ends with in a yarn. Then
better would be the uniformity, evenness.
Yarn hairiness:
 The shorter the fiber the higher will be
number of ends per yarn. This leads to
hairiness in yarn
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33. How…?continued…
Handle of the product:
 For two fibers, the longer and shorter.
Yarn of the same strength can be
produced with lower turns per length,
twist for longer one leading to softer
yarn.
 The softer the yarn the better would
be the handle of the product.
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34. How…?continued…
Luster of the product:
 The finer the fiber the higher will be
fibers per cross section leading to
uniform yarn and luster fabric
 for longer cotton fibers are finer
luster products will result from yarns
made from it.
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35. THANK YOU!
This is all we have !