ASTM D1440-96(2002)
(Test Method)Standard Test Method for Length and Length Distribution of Cotton Fibers (Array Method)
Standard Test Method for Length and Length Distribution of Cotton Fibers (Array Method)
SCOPE
1.1 This test method covers the determination of the fiber length and length distribution in loose cotton fibers.
Note 1—For another method for measuring fiber length, see Test Method D 1447.
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:D1440–96 (Reapproved 2002)
Standard Test Method for
Length and Length Distribution of Cotton Fibers (Array
Method)
This standard is issued under the fixed designation D 1440; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.5 pull, n—a group of fibers grasped by the forceps at
one time and drawn from the specimen in the combs.
1.1 This test method covers the determination of the fiber
3.1.6 upper quartile length, n—in testing of cotton fibers,
length and length distribution in loose cotton fibers.
that length which is exceeded by 25 % of the fibers by weight
NOTE 1—For another method for measuring fiber length, see Test
in the test specimen.
Method D 1447.
3.2 For definitions of other terms used in this test method,
1.2 This standard does not purport to address all of the
refer to Terminology D 123.
safety concerns, if any, associated with its use. It is the
4. Summary of Test Method
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
4.1 A sorting apparatus consisting of two banks of parallel
bility of regulatory limitations prior to use.
combs is used to straighten and align the fibers in a 75-mg test
specimen. The fibers are pulled from one bank of combs and
2. Referenced Documents
transferred to the other in such a manner that one end of each
2.1 ASTM Standards:
fiber is aligned with the base comb. The transfer is repeated to
D 123 Terminology Relating to Textiles
straighten the other ends of the fibers. As the fibers are
D 1441 Practice for Sampling Cotton Fibers for Testing
withdrawn from the combs for the third time, they are placed
D 1447 Test Method for Length and Length Uniformity of
in order of length on velvet covered boards. The pulls are
Cotton Fibers by Fibrograph Measurement
measured, and those that fall within each length interval are
D 1776 Practice for Conditioning Textiles for Testing
collected and weighed. From these weight-length data, the
upper quartile length, mean length, and coefficient of length
3. Terminology
variation are calculated.
3.1 Definitions:
5. Significance and Use
3.1.1 coeffıcient of variation, CV, n—a measure of the
dispersion of observed values equal to the standard deviation
5.1 The array method provides objective measurements for
for the values divided by the average of the values; may be
determining the fiber length and length distribution in a sample
expressed as a percentage of the average (CV %).
of cotton. The results can be plotted to show the length-weight
3.1.2 length group, n—allfibers,orpulls,whoselengthsfall
distribution of all the fibers in the sample. Data obtained from
within a given length interval.
array tests are useful in fiber length research studies, for
3.1.3 length interval, n—a class interval of ⁄8 in. (3 mm),
investigation of changes in fiber length distribution in ginning
usually designated by its midpoint length in odd-numbered
and mill processing, and for other research purposes.
sixteenths of an inch.
5.2 Upper quartile length is correlated with, but usually
1 1
Example:the0to ⁄8-in. interval is designated as ⁄16.
longer than, Fibrograph and 2.5 % span length as defined in
3.1.4 mean length, n—in testing of cotton fibers,theaverage
Test Method D 1447. Judgment must be used in making
length of all fibers in the test specimen based on weight-length
comparisons between length measures from arrays and mea-
data.
sures obtained by other methods, which may be basically
different.
5.3 The coefficient of length variation is a measure of length
ThistestmethodisunderthejurisdictionofASTMCommitteeD13onTextiles,
distribution, or nonuniformity of length. Because the fiber
and is the direct responsibility of Subcommittee D13.11 on Cotton and Fibers.
weight-length distribution is usually highly skewed, statistical
Current edition approved Nov. 10, 1996. Published March 1997. Originally
judgments based on the assumption of normality are not
published as D 1440 – 55. Last previous edition D 1440 – 90.
Annual Book of ASTM Standards, Vol 07.01. justified.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D1440
a and c—Banks of combs.
b—Forceps, tips padded with hard leather, for transferring fibers from one set of combs to the other.
d—Depressor for placing fibers in combs.
f—Dissecting needle.
g—Fork for scooping up fiber groups off velvet surface.
h—Aluminum plate covered with velvet cloth.
i—Special rule for measuring length of fiber groups.
k—Smooth plate for placing fibers onto velvet surfaces.
l—Wire rack for holding fiber groups wrapped in papers.
m—Smooth pointed tweezers.
n—Lift for raising combs in place.
o—Rack for holding velvet-covered boards.
p—Velvet-covered boards on which several pulls have been arrayed.
NOTE 1—Other accessories required for length arraying, not shown above, consist of the following: small whisk broom for cleaning velvet surfaces,
one pair of tweezers with smooth round tips, forceps similar to b but having tips padded with rubber for laying groups on velvet surfaces, small papers
1 1 1
for wrapping groups of fibers (papers 2 ⁄2 by 3 in. (62 by 75 mm)) with small envelopes for them (2 ⁄2 by 4 ⁄4 in. (62 by 110 mm)), and balances having
ranges from 0 to 25 mg and 0 to 100 mg.
FIG. 1 Combs and Accessories for Arraying Fibers According to Length
5.4 The array method makes a physical separation of fibers 6.4 Standard Calibration Cotton Samples, for the calibra-
of different lengths. It therefore serves as a standard, or tion of array length measurements.
benchmark, with which other methods may be compared and
NOTE 2—Standard calibration cotton samples are available from the
by which their precision and accuracy may be judged.
Cotton Division, Agricultural Marketing Service, U.S. Department of
5.5 Test Method D 1440 for testing length and length
Agriculture, 3275 Appling Rd., Memphis, TN 38133.
distribution of cotton fibers (array method) is not commonly
6.5 Secondary Standard Cotton—Lots of cotton the length
used for acceptance testing of commercial shipments.
of which has been established by extensive comparisons with
USDA standards.
6. Apparatus and Materials
6.1 Double Bank Sorter, and equipment as illustrated in Fig.
7. Sampling
1. The method outlined here is especially adapted to the
7.1 Prepare the laboratory sample as directed in Test
Suter-Webb Duplex Cotton Fiber Sorter, but the procedure
Method D 1441. Take either two or three subsamples depend-
may be carried out with other similar apparatus with more or
ing on the precision desired. Take subsamples that weigh
less obvious alterations.
approximately 80 mg each for use in preparing the test
6.2 Balance, with a capacity of at least 25 mg and a
specimen in one of the following manners:
sensitivity of 60.05 mg.
7.1.1 From a hand sliver, carefully separate a 2-in. (50-mm)
6.3 Balance, with a capacity of at least 100 mg and a
length of the sliver for each subsample.
sensitivity of 60.1 mg.
7.1.2 From a mechanically blended 3-g sliver, separate 2-in.
(50-mm) subsamples.
7.1.3 From a mechanically blended 10-g sliver, pull out of
The sole source of supply of the apparatus known to the committee at this time
themiddleofthesampleasubsampleabout2in.(50mm)long,
is the Alfred Suter Co., New York, NY. If you are aware of alternative suppliers,
extending through its whole thickness, and wide enough to
pleaseprovidethisinformationtoASTMHeadquarters.Yourcommentswillreceive
weigh approximately 80 mg. Take subsamples from near the
careful consideration at a meeting of the responsible technical committee, which
you may attend. beginning, midway, and near the end of the sliver.
D1440
7.2 If the laboratory samples have not been in the standard the technician must make some appropriate change in tech-
atmosphere for at least 2 h before the preparation of sub- nique and repeat the check test until acceptable results are
samples,bringthesubsamplestoapproximateequilibriumwith obtained.
the standard atmosphere for testing before preparing speci- 10.3 If two or three technicians are available, have each
mens. Exposure to moving air in the laboratory for2his
technician sort one of the three specimens.
sufficient.
10.4 First Transfer:
10.4.1 Place the test specimen in the left bank of combs
8. Preparation of Test Specimen
perpendicular to and approximately in the center of the combs.
Using the depressor (Fig. 1, d), depress the test specimen at
8.1 Prepare one specimen from each of the three sub-
least ⁄16 in. (2 mm) below the tips of the comb teeth, but no
samples. Gently parallelize the fibers by hand. Remove all
lower than half the length of the teeth. The comb fork can be
foreign matter, but do not discard any fibers.
used to raise any fibers that are depressed below this level.
8.2 Separate from each subsample, by longitudinal division,
10.4.2 Drop front combs of the left bank until a smaller
a portion weighing approximately 76 mg. If the specimen
number of fibers protrude beyond the comb nearest the
weighs more than 77 mg, reduce its weight by removing a
operator.
small group of fibers from the side of the specimen. If the
10.4.3 Griptheendsofafewofthesefiberswiththeforceps
specimen weighs less than 75 mg, add a small group of fibers
(Fig. 1, b) and withdraw them from the combs with a smooth
taken from the side of the subsample. Never remove fibers
horizontal motion.
from either the specimen or subsample by pulling from the
10.4.4 Continue holding the fiber ends with the forceps.
ends, as this tends to remove the longest fibers.After adjusting
Place the forceps at the farther edge of the right bank of combs
the specimen weight to approximately 76 mg, condition the
and draw the fibers carefully through the combs until the edge
specimen and the remaining portion of the subsample in
of the forceps is just touching the near edge of the first comb.
accordance with Section 9.
Release the fibers from the forceps. With the depressor, push
the fibers down for a short distance into the teeth of the combs.
9. Conditioning
Repeat this procedure until the transfer of all protruding fibers
9.1 Practice D 1776 covers the conditioning of textiles for
is complete.The fibers should not protrude more than ⁄16 in. (2
testing. If the laboratory samples have a moisture content of
mm) beyond the nearer comb of the right bank.
10 % or higher, Practice D 1776 should be used to condition
10.4.5 Drop an additional comb of the left bank and
the samples for testing. For samples below 10 % moisture
continuetransferringthefibers.Donotwithdrawinonepullall
content, the conditioning procedure outlined in 9.2 and 9.3 is
of the fibers protruding from a comb, but take four or more
considered adequate for length testing by this test method.
separate pulls, withdrawing in each pull those fibers which
9.2 If the laboratory samples have not been in the standard
protrude farthest.The width of the specimen placed in the right
atmosphere for at least 2 h before the preparation of the
comb bank should be no greater than the width of the forceps
subsample, bring the subsamples to approximate equilibrium
being used.
with the standard atmosphere for testing before preparing
10.4.6 Continue the transferring procedure, dropping combs
specimens. Exposure to moving air in the laboratory for4his
as necessary, until all the fibers have been transferred from the
sufficient.
left to the right set of combs.
9.3 After the specimens have been prepared, condition them
10.4.7 Using the dissecting needle (Fig. 1, f ), gently un-
in the standard atmosphere for testing. Exposure to moving air
tangle the fiber ends extending beyond the front comb. With
in the standard atmosphere for a minimum period of2his
the forceps, pull out any fibers that extend more than approxi-
adequate for this test method.
mately ⁄16 in. (2 mm) beyond the front comb and replace them
in the same bank of combs in the manner described in 10.4.4.
10. Procedure
Continue until the front ends of the fibers are straight and even.
10.4.8 Drop the back combs of the bank containing the
10.1 Weigh the conditioned specimen to the nearest 0.1 mg.
Do not touch the specimen with the fingers after conditioning. specimen until fibers are encountered. Pull these protruding
fibers from the back of the combs and place them on the test
If the specimen weighs more than 75.4 mg, use the tweezers
(Fig. 1, m) to remove a small group of fibers from the side of specimen in the same manner as was done in the transfer of the
specimen. Continue this straightening process until fibers
the specimen. If the weight is less than 74.6 mg, add a small
pulled from the back combs extend through the front comb and
group of fibers taken with tweezers from the side of the
the ends of the specimen are straight and even. This completes
subsample. Do all sorting, measuring, and weighing in the
the first transfer.
standard atmosphere for testing.
10.5 Second Transfer:
10.2 Before testing other samples, each technician shall
10.5.1 Raise the empty bank of combs to the working
have made an array on a check test cotton (Note 2), if this has
position and rotate the sorting apparatus 180° so that the
not been done during the previous month. Results of regularly
specimen is on the left.
scheduled check tests may be used for this purpose. If the
results do not agree with the standard value for the check test 10.5.2 Repeat the procedure used in the first transfer, steps
cotton within 60.02 in. (0.51 mm) in both upper quartile and 10.4.2-10.4.8 through , transferring the specimen back to the
mean length and 62.0 % for the coefficient of length variation, first set of combs.
D1440
10.6 Array: 10.8.1 Beginning with the longest, weigh each length group
onthe25-mgbalance.Recordtheweightstothenearest0.1mg
10.6.1 Insert top combs.
in appropriate spaces on the data sheet (Fig. 2).
10.6.2 Revolve the sorting apparatus 180° and drop front
10.8.2 If the sum of the weights is 75.0 6 2.0 mg, record it
combs until the longest fibers are reached.
on the data sheet. If the sum is not within these limits, reweigh
10.6.3 Using the rubber-tipped forceps (Fig. 1, b), pull out a
the array. If the sum of the second weighings is not within the
few of the longest fibers protruding from the front comb. Lay
prescribed limits, discard the array.
the pull near one end of the velvet covered board and near the
10.8.3 Iftestsforfiberweightperunitlengthormatu
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