ASTM D7025-09(2021)e1
(Test Method)Standard Test Method for Assessing Clean Flax Fiber Fineness
Standard Test Method for Assessing Clean Flax Fiber Fineness
SIGNIFICANCE AND USE
5.1 This test method for determining fineness of cleaned flax fibers is considered satisfactory for acceptance testing of commercial shipments when the levels are controlled by use of a range of calibration standards.
5.1.1 If there are differences of practical significance between reported test results for two or more laboratories, comparative tests should be performed by those laboratories to determine if there is a statistical bias between them, using competent statistical assistance. As a minimum, use test samples that are as homogenous as possible, are drawn from the material from which the disparate test results were obtained, and are randomly assigned in equal numbers to each laboratory for testing. These test results from the two laboratories should be compared using a statistical test for unpaired data, at a probability level chosen prior to the testing series. If a bias is found, either its cause must be found and corrected, or future test results for that material must be adjusted in consideration of the known bias.
5.2 The resistance that a plug of flax fibers offers to the flow of air is measured as an approximate indication of the average relative fineness of the fibers.
5.2.1 The total surface area of finer fibers has a larger per unit mass and increased resistance to airflow than do coarser fibers.
5.3 Instruments are available to indicate the resistance to air flow using either compressed air or a vacuum; and are constructed (1) to measure airflow under constant pressure drop across the plug, (2) to measure pressure drop when a constant flow of air is maintained, or (3) to indicate resistance to air flow from both a balanced and unbalanced Wheatstone bridge.
5.4 The reliability of the results of any test method depends primarily upon how well the specimens tested represent the original source material. Flax fibers are different from many textile fibers, such as cotton or synthetic ones, in that they are not individual filaments but bu...
SCOPE
1.1 This test method provides two options that cover the determination of the fineness of clean loose flax fibers by: Option 1, measuring the specific surface area by the resistance of a plug of flax fibers to air flow under prescribed conditions, or Option 2, estimating the mass per unit length.
Note 1: For other methods for determining the fineness of fibers refer to Appendix X1.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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Designation: D7025 − 09 (Reapproved 2021)
Standard Test Method for
Assessing Clean Flax Fiber Fineness
This standard is issued under the fixed designation D7025; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Research report information was added to Section 18 editorially in August 2021.
1. Scope 3. Terminology
1.1 This test method provides two options that cover the 3.1 For terminology relating to Flax, see Terminology
D6798.
determination of the fineness of clean loose flax fibers by:
Option 1, measuring the specific surface area by the resistance 3.1.1 The following terms are relevant to this standard:
fineness index and specific surface index.
of a plug of flax fibers to air flow under prescribed conditions,
or Option 2, estimating the mass per unit length.
3.2 For definitions of all other textile terms, see Terminol-
ogy D123.
NOTE 1—For other methods for determining the fineness of fibers refer
to Appendix X1.
4. Summary of Test Method
1.2 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
4.1 Using Option 1, a predetermined mass of clean loose
standard.
flaxfibersgeneratedbyusingamechanicalblenderisplacedin
the specimen holder and compressed to a fixed volume.
1.3 This standard does not purport to address all of the
4.1.1 The resistance to airflow is measured using a cotton
safety concerns, if any, associated with its use. It is the
fiber instrument that provides a reading. This reading is
responsibility of the user of this standard to establish appro-
convertedtoaspecificsurfaceindexwhichisderivedfromthe
priate safety, health, and environmental practices and deter-
linear density of flax.
mine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accor-
4.2 Using Option 2, the average linear density of single
dance with internationally recognized principles on standard-
fibers in a bundle is calculated from mass and length measure-
ization established in the Decision on Principles for the
ments on the bundle and the number of single fibers in the
Development of International Standards, Guides and Recom-
bundle.
mendations issued by the World Trade Organization Technical
NOTE 2—There may be no overall correlation between the results
obtainedwithOptions1and2.Consequently,thesetwooptionscannotbe
Barriers to Trade (TBT) Committee.
used interchangeably. In case of controversy, Option 1 shall prevail.
2. Referenced Documents
5. Significance and Use
2.1 ASTM Standards:
5.1 This test method for determining fineness of cleaned
D123Terminology Relating to Textiles
flax fibers is considered satisfactory for acceptance testing of
D1441Practice for Sampling Cotton Fibers for Testing
commercialshipmentswhenthelevelsarecontrolledbyuseof
D1577Test Methods for Linear Density of Textile Fibers
a range of calibration standards.
D1776/D1776MPractice for Conditioning and Testing Tex-
5.1.1 If there are differences of practical significance be-
tiles
tween reported test results for two or more laboratories,
D6798Terminology Relating to Flax and Linen
comparativetestsshouldbeperformedbythoselaboratoriesto
determine if there is a statistical bias between them, using
competent statistical assistance. As a minimum, use test
ThistestmethodisunderthejurisdictionofASTMCommitteeD13onTextiles
samples that are as homogenous as possible, are drawn from
and is the direct responsibility of Subcommittee D13.17 on Bast Fibers and Plants.
the material from which the disparate test results were
Current edition approved Feb. 1, 2015. Published August 2021. Originally
ɛ1
obtained, and are randomly assigned in equal numbers to each
approved in 2004. Last previous edition approved in 2015 as D7025–09 (2015) .
DOI: 10.1520/D7025-09R21E01.
laboratory for testing. These test results from the two labora-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
tories should be compared using a statistical test for unpaired
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
data, at a probability level chosen prior to the testing series. If
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. abiasisfound,eitheritscausemustbefoundandcorrected,or
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D7025 − 09 (2021)
future test results for that material must be adjusted in 6.3 AirSupply,tofurnishtherequiredpressureorvacuumto
consideration of the known bias. operate the instrument in accordance with the manufacturer’s
instructions.
5.2 Theresistancethataplugofflaxfibersofferstotheflow
6.4 Fineness Calibration Standards, viscose rayon fibers
of air is measured as an approximate indication of the average
relative fineness of the fibers. reducedto5cmwithanominallineardensityof1.1,1.5,or3.0
denier and a nominal specific surface fineness index value of
5.2.1 The total surface area of finer fibers has a larger per
2.55, 2.9, or 4.0.
unit mass and increased resistance to airflow than do coarser
fibers.
6.5 Mechanical Cutting Device, Template, Stelometer
Clamps,orDie,havingaprecisionof0.1%designedtopermit
5.3 Instrumentsareavailabletoindicatetheresistancetoair
cutting fibers of a specified length.
flow using either compressed air or a vacuum; and are
constructed (1) to measure airflow under constant pressure
6.6 Stationary Coarse Comb, approximately 63 mm in
drop across the plug, (2) to measure pressure drop when a
width and having needles approximately 12.5 mm in length
constant flow of air is maintained, or (3) to indicate resistance
and spaced 19 needles to the centimeter.
to air flow from both a balanced and unbalanced Wheatstone
6.7 Mechanical Blender, to open and blend the flax fibers.
bridge.
5.4 The reliability of the results of any test method depends
7. Sampling and Selection of Specimens
primarily upon how well the specimens tested represent the
7.1 Take the test specimen by random sampling from the
original source material. Flax fibers are different from many
laboratory sample prepared as recommended in Practice
textile fibers, such as cotton or synthetic ones, in that they are
D1441.
not individual filaments but bundles of fibrous material that
7.1.1 Pass the test specimen through a mechanical blender
may or may not be completely separated into individual
to open and blend fibers as directed in 6.1 of recommended
filamentsandthereforehaveahighdegreeofvariability.While
Practice D1441.
cleaningandprocessingcanproduceseparationandchangesin
length, there is no certainty of fibrillation of the fibrous
8. Conditioning
material.
8.1 Bring the laboratory sample from the prevailing atmo-
NOTE 3—Amodification of this test method can be used in commercial
sphere to moisture equilibrium for testing which is 21°C 6
trading to select bales that will conform to contract guarantees for
1°C (70°F 6 2°F) and 65% 6 2 % relative humidity and
specifiedspecificsurfaceindex.Forthispurpose,theusualpracticetotest
only one specimen per sample.
check the equilibrium as directed in Practice D1776/D1776M.
No preconditioning is required.
5.4.1 This specific surface index reading is related to the
average linear density of single fibers in a bundle calculated
OPTION 1: SPECIFIC SURFACE INDEX FINENESS
from mass and length measurements on the bundle and the
number of single fibers in the bundle.
9. Scope
5.5 The specific surface index of flax fibers may be a
9.1 This option covers the fineness measurement by resis-
function of fineness, degree of retting, cleanliness, variety,
tancetoairflowwhichisconvertedtothespecificsurfaceindex
bundle separation, and plant maturity harvest date. This fine-
to help characterize fibers by approximating the fineness. (See
ness of flax fibers affects their mill processing and spinning
Note 2.)
performance as well as contributes significantly to the appear-
ance and strength of the yarns produced.
10. Procedure
5.6 The accuracy of weighing can be controlled by the
10.1 Test the conditioned calibration specimens in the
number of fibers composing the bundle. However, with short
atmosphere for testing textiles.
fiber of low linear density the number of fibers to be counted
10.1.1 Set up and adjust the instrument as directed in the
becomes prohibitive unless the bundle mass is kept low.
manufacturer’s instructions.
10.1.2 Adjust the instrument if necessary to secure values,
6. Apparatus and Materials
which correspond to the values assigned to the Calibration
6.1 Air-Flow Instrument, a device calibrated in micronaire Reference Standards at the beginning of each testing period.
readings or yielding numerical readings from which specific
10.2 Useamechanicalblendertwicetoopenandblendeach
surface index readings can be computed.
standard viscose rayon fiber.
6.2 Balances, with one having a capacity suitable for mass
10.3 Using 5 g specimens, make two tests with each
of the specific surface index specimen to be used and sensitiv-
standard viscose rayon fiber.
ity of at least 0.2% of the mass and another for linear density
10.3.1 Whentheaverageofthetworesultsisnotwithin0.1
havingacapacityof15mgandsensitivityofatleast0.005mg.
unit of the established specific surface index reading, recheck
the instrument and the technique used by the operator.
10.3.2 Check the instrument against the standards again at
Apparatus and accessories are commercially available. the end of each testing period.
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D7025 − 09 (2021)
10.3.3 When incorrect readings on the standards
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