ASTM D2821-00(2005)
(Test Method)Standard Test Method for Measuring the Relative Stiffness of Leather by Means of a Torsional Wire Apparatus
Standard Test Method for Measuring the Relative Stiffness of Leather by Means of a Torsional Wire Apparatus
SCOPE
1.1 This test method describes the use of a torsional apparatus for measuring the relative stiffness of gloving leathers. This test method does not apply to wet blue.
1.2 The values stated in SI units are to be regarded as the standard. The values shown in parentheses are provided for information only.
1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of whoever uses this standard to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:D2821–00(Reapproved2005)
Standard Test Method for
Measuring the Relative Stiffness of Leather by Means of a
Torsional Wire Apparatus
This standard is issued under the fixed designation D 2821; 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. Significance and Use
1.1 This test method describes the use of a torsional 3.1 This test method is designed to measure the apparent
apparatus for measuring the relative stiffness of gloving leath- torsionalmodulusofaleatherspecimen.Experiencehasshown
ers. This test method does not apply to wet blue. that the torsion modulus of leather is directly related to the
1.2 The values stated in SI units are to be regarded as the characteristic known as stiffness when felt in a glove.
standard. The values shown in parentheses are provided for
4. Apparatus
information only.
1.3 This standard does not purport to address all of the 4.1 Torsion Apparatus —The torsional apparatus, Fig. 1,
shall consist of a torsion head, A, capable of being turned
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
Gloves were made from the neck and butt areas of cattlehide work-glove
bility of regulatory limitations prior to use.
leather selected for 3° of softness varying from soft to firm.These were ranked from
softest to firmest by 20 individuals. Since there was some overlapping of rank as
2. Referenced Documents
assigned by individual observers, the final rank was assigned according to highest
numberofselections.Specimensofleathercutfromthesidesintheareafromwhich
2.1 ASTM Standards:
each glove was cut were tested for stiffness according to this test method.At 90° of
D 1053 Test Method for Rubber Property-Stiffening at Low
twist, the stiffness values gave a ranking similar to that obtained by feel. Specimens
Temperatures: Flexible Polymers and Coated Fabrics
cut parallel to the backbone gave more consistant ranking than specimens cut
perpendicular to the backbone. This undoubtedly reflects the fact that work gloves
D 1610 Practice for Conditioning Leather and Leather
are cut from a side with the fingers parallel to the backbone. A report of these
Products for Testing
experiments and data used for calculation of precision and accuracy are on file at
ASTM Headquarters.
The method is similar to Test Method D 1053. The original apparatus was
This test method is under the jurisdiction ofASTM Committee D31 on Leather described by Williamson, I., British Plastics, Vol 23, 1950, pp. 87–90, 102; and
and is the direct responsibility of Subcommittee D31.04 onApparel and Upholstery. typical examples of the results of its use on leather were given in a paper by
This test method was developed in cooperation with theAmerican Leather Chemists Witnauer, L. PA, and Palm, W. E., Journal, American Leather Chemist’s Assn.,
Assn. JALCA, Vol 59, 1964, pp. 246–258. Working drawings for construction of the
Current edition approved Sept. 1, 2005. Published September 2005. Originally apparatus are available at nominal cost fromASTM Headquarters, 100 Barr Harbor
approved in 1969 as D 2821 – 69T. Last previous edition approved in 2000 as Drive, W. Conshohocken, PA19428-2959. RequestAdjunctADJD282102. There is
D 2821 – 00. no known source of supply of the equipment. The former producer, Fulton County
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Machine and Supply Co., Inc. is no longer in business. If you are aware of
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM alternative suppliers, please provide this information to ASTM Headquarters. Your
Standards volume information, refer to the standard’s Document Summary page on comments will receive careful consideration at a meeting of the responsible
the ASTM website. technical committee, which you may attend.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D2821–00 (2005)
4.4 Specimen Clamps—Two clamps shall be provided for
holding each test specimen. The top clamp, C, shall be
mounted at the bottom of the torsion wire. The bottom clamp,
E, shall be fashioned to move up and down without binding
within guides, F, mounted in the base. The weight of bottom
clamp E shall be 15 6 0.01 g.
5. Test Specimens
5.1 Unless otherwise specified in the detailed specification,
cutthespecimenusingasharpdiemeasuring12.70 60.03mm
(0.5006 0.001 in.) wide and 114 6 2 mm (4.5 6 0.1 in.) long.
When known the direction to the backbone shall be indicated.
Itisgoodpractice,however,toincludeacontrolspecimenwith
known twist characteristics.
5.2 Condition the specimen as specified in Practice D 1610.
6. Preparation of Apparatus
6.1 Clamp the specimen in the testing apparatus as de-
scribed below so that 89 6 2 mm (3.5 6 0.1 in.) of the
specimen is free between the clamps. It is advisable to mark
this distance on the specimen using a bench marker.
6.2 Insert the specimen into the jaws of the bottom clamp,
E, until the edge of the clamp meets the bench mark, and
FIG. 1 Torsion Apparatus
tighten the two set screws using finger tip pressure. Be sure the
specimen is perpendicular to the jaws of the clamp.
6.3 Insert the other end of the specimen into the jaws of the
through a complete circle in a plane normal to the torsion wire.
upper clamp, up to the bench mark and tighten the two set
The torsion head is equipped with an upper dial or protractor,
screws using finger tip pressure. Be sure the specimen is
K, graduated from 0 to 360° in increments not greater than 5°,
perpendicular to clamp.
and a fixed index pointer, L. The protractor is attached to the
6.4 Insert the bottom clamp into the clamp guide, F.
torsion head by means of a friction bearing to permit move-
6.5 Unlock the top dial by turning knobG counterclockwise
ment for adjusting the zero point.The top of the torsion wire is
about ⁄4 turn.
attached to the torsion head at knob H by set screw B and
6.6 Bring both clamps into parallel position by turning knob
passes through the center of a loosely fitting sleeve gripped by
H, or knob M, either clockwise or counterclockwise so there is
the friction bearing. The torsion head support carries a split
no twist to the specimen. When the clamps are parallel adjust
bearing which can be activated by knob G, thus locking the
the top clamp indicator, I, so it is over the “0” mark on the
sleeve carrying the wire and permitting adjustment of the zero
lower dial, J, by holding the clamp parallel in one hand and
point of the protractor without disturbing the position of the
turning the indicator. The indicator is attached to the upper
torsionwire.Thebottomofthewireshallbefastenedtothetest
clamp by a friction clasp.
specimen clamp, C, by means of a set screw connector, D.A
...
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