ASTM D1442-93
(Test Method)Standard Test Method for Maturity of Cotton Fibers (Sodium Hydroxide Swelling and Polarized Light Procedures)
Standard Test Method for Maturity of Cotton Fibers (Sodium Hydroxide Swelling and Polarized Light Procedures)
SCOPE
1.1 This test method covers the determination of the percentage of mature fibers in a sample of loose, chemically untreated cotton fibers, whether taken before processing or unravelled from a textile product.
1.2 This test method gives two optional procedures for determining maturity, as follows:
1.2.1 Procedure 1--Sodium Hydroxide Swelling.
1.2.2 Procedure 2--Polarized Light.
Note 1--For other test methods for the determination of maturity of cotton fibers refer to Test Methods D1464 and D2480.
1.3 The values stated in SI units are to be regarded as standard. No other units of measure are included in this standard.
1.4 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: D 1442 – 93 An American National Standard
Standard Test Method for
Maturity of Cotton Fibers (Sodium Hydroxide Swelling and
Polarized Light Procedures)
This standard is issued under the fixed designation D 1442; 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 3.1.3 micronaire reading, n—a relative measurement of
fiber fineness derived from the porous plug air-flow method.
1.1 This test method covers the determination of the per-
3.1.4 For definitions of other terms used in this method,
centage of mature fibers in a sample of loose, chemically
refer to Terminology D 123.
untreated cotton fibers, whether taken before processing or
3.2 Definitions of Terms Specific to This Standard:
unravelled from a textile product.
3.2.1 immature fibers, n—in testing with sodium hydroxide
1.2 This test method gives two optional procedures for
solutions, fibers that have either swollen and assumed a spiral
determining maturity, as follows:
form similar to that shown in Fig. 1, or remained flat, thinly
1.2.1 Procedure 1—Sodium Hydroxide Swelling.
outlined, and almost transparent as shown in Fig. 2, with total
1.2.2 Procedure 2—Polarized Light.
wall width less than the lumen width.
NOTE 1—For other test methods for the determination of maturity of
3.2.2 immature fiber, n—observed under polarized light,
cotton fibers refer to Test Methods D 1464 and D 2480.
fibers that appear purple, indigo, or blue that turn orange or
yellow-orange upon rotation to the subtractive position and
2. Referenced Documents
show parallel extinction upon removal of the selenite plate (see
2.1 ASTM Standards:
Table 1).
D 123 Terminology Relating to Textiles
D 1440 Test Method for Length and Length Distribution of
A
TABLE 1 Colors of Cotton Fibers Viewed with Polarized Light
Cotton Fibers (Array Method)
Without Selenite Plate With Selentite Plate
D 1442 Test Method for Maturity of Cotton Fibers (Sodium
Fiber Subtractive
2 Additive Colors
Hydroxide Swelling and Polarized Light Procedures)
Classification First Order Colors
Second Order First Order
D 1447 Test Method for Length and Length Uniformity of
Mature light yellow yellow light yellow
Cotton Fibers by Fibrograph Measurement
white green yellow
D 1464 Test Method for Differential Dyeing Behavior of Immature gray-blue blue orange-yellow
gray purple orange
Cotton
A
Classified according to Mary Anna Grimes, “Polarized Light Preferred for
D 1769 Test Method for Linear Density of Cotton Fibers
2 Maturity Tests,” Textile World, February, 1945.
(Array Sample)
D 2480 Test Method for Maturity Index and Linear Density
2 3.2.3 mature fibers, n—in testing with sodium hydroxide
of Cotton Fibers by the Causticaire Method
solutions, fibers that have swollen into unconvoluted and
3. Terminology almost rod-like shapes illustrated in Fig. 3, where total wall
width is equal to or greater than the lumen width.
3.1 Definitions:
3.2.4 mature fibers, n—observed under polarized light,
3.1.1 cotton fiber maturity, n—the degree of fiber wall
fibers that appear yellow, yellow-green, or green and are
development; the ratio of fiber wall width to lumen width.
yellow or light yellow upon rotation to the subtractive position
3.1.1.1 Discussion—When cotton fibers are treated with a
(through 90°) and show little or no parallel extinction upon
sodium hydroxide solution, mature fibers have a total wall
removal of the selenite plate (see Table 1).
width equal to or greater than the lumen width, and immature
fibers have a total wall width less than the lumen width.
NOTE 2—Cotton fibers observed under polarized light that appear blue
3.1.2 lumen, n—in vegetable fibers, the central canal of the
or green may be classified separately for a finer distinction of fiber
maturity (see Table 1).
fiber.
3.2.5 test specimen, n—in cotton maturity tests, the series of
slides observed by one technician as one-half of the test.
This test method is under the jurisdiction of ASTM Committee D-13 on
Textiles, and is the direct responsibility of Subcommittee D 13.11 on Cotton Fibers.
4. Summary of Test Method
Current edition approved June 15, 1993. Published August 1993. Originally
4.1 Fibers are laid parallel on a microscope slide, covered
published as D 1442 – 52 T. Last previous edition D 1442 – 75.
Annual Book of ASTM Standards, Vol 07.01. with a cover glass, treated with a mounting medium, and the
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 1442
FIG. 2 Immature Fiber (Type B)
the growing season interfere with this relationship. Thus two
cottons having the same linear density, or having the same
average wall thickness as indicated by air-flow instruments,
may vary greatly in maturity, that is, a cotton having extremely
FIG. 1 Immature Fiber (Type A)
variable wall thickness may contain more immature fibers than
another cotton of the same Micronaire reading composed of
magnified images are then classified as mature or immature
fibers having very uniform wall thickness.
fibers.
5.3 The Sodium Hydroxide Swelling (Procedure 1) has been
4.2 The method offers two procedures for classifying the
used in judging other maturity tests such as the Causticaire and
fibers as mature or immature:
the differential dye methods, in which the individual fibers are
4.2.1 Procedure 1, Sodium Hydroxide Swelling, which uses
not examined.
an 18 % solution of sodium hydroxide as the mounting
5.4 Finer distinctions between different degrees of fiber wall
medium and a laboratory microscope for viewing the fibers at
development can be made with the Polarized Light procedure
a magnification of 4003.
than with the Sodium Hydroxide Swelling procedure. The
4.2.2 Procedure 2, Polarized Light, which uses water or
Polarized Light procedure gives a view of the fiber in its
clear mineral oil as the mounting medium and requires a
natural state so that fibrillar structure, striations, reversals, etc.,
polarizing microscope giving a magnification of 1003. Fibers
are clearly visible as are growth abnormalities and variations in
are classified according to their second-order interference
wall thickness. This method may be preferred by botanists,
colors, using a first-order red selenite plate (Table 1).
geneticists, and plant physiologists, while the Sodium Hydrox-
ide Swelling procedure may be preferred for routine testing of
5. Significance and Use
large numbers of samples. Technicians are more easily trained
5.1 Information regarding the percentage of immature fibers
for the latter method. Arbitrary classification as to maturity
is desirable because immature fibers: (1) break easily during must be made with both methods.
processing; (2) have a tendency to form neps; (3) have a
5.5 This method is not considered satisfactory for accep-
tendency to become entangled around particles of trash and tance testing because between laboratory precision can be poor.
leaf, thus making cleaning more difficult and increasing the In some cases the purchaser and seller may have to test a
amount of fiber removed with foreign matter; (4) adversely commercial shipment of one or more specific material by an
affect yarn and fabric appearance; and (5) may appear differ- appropriate method even though the method has not been
ently after dyeing. recommended for acceptance testing of commercial shipments.
5.2 Maturity has a high positive correlation with linear In such a case, if there is a disagreement arising from
density, but genetic differences and differences in wall thick- differences in values reported by the purchaser and seller in
ness caused by plant diseases, soil, and water conditions during using this method for acceptance testing, the statistical bias, if
D 1442
6.1.7 Mounting Medium, sodium hydroxide (NaOH) solu-
tion, 18 %, sp gr 1.197 6 0.002 at 60 to 70°F (16 to 20°C) in
a dropping bottle.
6.2 Procedure 2:
6.2.1 Polarizing Microscope equipped with a polarizer, an
analyzer, a first-order red selenite plate, a cross-hair eyepiece
mounted so that the hairs make a 45-deg angle with the plane
of polarization, a rotatable, mechanical stage, and a microscope
lamp. The possible magnification must be at least 1003.
6.2.2 Mounting Medium, water or clear mineral oil in a
dropping bottle.
6.2.3 Other Apparatus as specified in 6.1.2-6.1.6 for Pro-
cedure 1.
7. Safety Precaution
7.1 The sodium hydroxide solution used in Procedure 1 is
caustic and corrosive. Use care in its preparation and applica-
tion to avoid contact with the skin or with equipment, espe-
cially the microscope objective, which may be permanently
damaged if the solution is not removed immediately following
contact. Clear water and a soft tissue will remove the solution.
8. Sampling and Preparation of Specimens
8.1 Three sources of specimens may be used with either
procedure. If Suter-Webb array length groups are not available,
either of the other two sources of specimens may be used.
8.1.1 Option A—Suter-Webb Array Length Groups—
Prepare the array length groups as directed in Method D 1440.
1 3
From one array discard the ⁄16-in. (1.6-mm) and ⁄16-in.
(4.8-mm) length groups and any other length groups containing
less than 1 mg of fibers. From each length group remaining,
FIG. 3 Mature Fiber
remove a bundle of approximately 100 fibers by lengthwise
separation beginning with the longest group. Place the fibers on
any, between the laboratory of the purchaser and the laboratory
a microscope slide, spread them carefully to a width of 30 to 40
of the seller should be determined with comparison based on
mm. Cover the fibers with a cover glass and apply a drop of the
tested specimens randomly drawn from one sample of material
mounting medium to one corner. Tap the cover glass to cause
of the type being evaluated.
the mounting medium to spread more rapidly and help prevent
air bubbles. Mark the slide with the length group identification.
6. Apparatus and Reagents
The series of slides shall constitute a test specimen. Have a
6.1 Procedure 1:
second operator prepare a second test specimen from a second
6.1.1 Microscope or Microprojector, which will give a
array of the sample.
magnification of approximately 4003, equipped with a me-
chanical stage, microscope lamp, and viewing aid such as a
NOTE 3—The sampling method described in 8.1.1 has been used for a
longer period of time and given slightly more reliable results than the
Euscope or projection screen.
other sampling methods.
6.1.2 Metal Comb, rake-type.
6.1.3 Microscope Slides, 2 by 3 in. (50 by 75 mm), and
8.1.2 Option B, Laboratory Blended Samples—Take a sub-
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