ASTM_D_2821_-_14.pdf

Designation:D282114Standard Test Method forMeasuring the Relative Stiffness of Leather by Means of aTorsional Wire Apparatus1This standard is issued under the fixed designation D2821;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 This test method describes the use of a torsionalapparatus for measuring the relative stiffness of gloving leath-ers.This test method does not apply to wet blue.1.2 The values stated in SI units are to be regarded as thestandard.The values shown in parentheses are provided forinformation only.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D1053 Test Methods for Rubber PropertyStiffening atLow Temperatures:Flexible Polymers and Coated FabricsD1610 Practice for Conditioning Leather and Leather Prod-ucts for Testing3.Significance and Use3.1 This test method is designed to measure the apparenttorsional modulus3of a leather specimen.Experience hasshown that the torsion modulus of leather is directly related tothe characteristic known as stiffness when felt in a glove.44.Apparatus4.1 Torsion Apparatus5 The torsional apparatus,Fig.1,shall consist of a torsion head,A,capable of being turnedthrough a complete circle in a plane normal to the torsion wire,N.The torsion head is equipped with an upper dial orprotractor,K,graduated from 0 to 360 in increments notgreater than 5,and a fixed index pointer,L.The protractor isattached to the torsion head by means of a friction bearing topermit movement for adjusting the zero point.The top of thetorsion wire is attached to the torsion head at knob H by setscrew B and passes through the center of a loosely fitting sleevegripped by the friction bearing.The torsion head supportcarries a split bearing which can be activated by knob G,thuslocking the sleeve carrying the wire and permitting adjustmentof the zero point of the protractor without disturbing theposition of the torsion wire.The bottom of the wire shall befastened to the test specimen clamp,C,by means of a set screwconnector,D.A pointer,I,mounted above a fixed dial,J,shall1This test method is under the jurisdiction of ASTM Committee D31 on Leatherand is the direct responsibility of Subcommittee D31.04 on Apparel.This testmethod was developed in cooperation with the American Leather Chemists Assn.Current edition approved April 1,2014.Published May 2014.Originallyapproved in 1969 as D2821 69T.Last previous edition approved in 2009 asD2821 09.DOI:10.1520/D2821-14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3This test method is similar to Test Method D1053.The original apparatus wasdescribed by Williamson,I.,British Plastics,Vol 23,1950,pp 87-90,102;andtypical examples of the results of its use on leather were given in a paper byWitnauer,L.PA,and Palm,W.E.,Journal,American Leather Chemists Assn.,JALCA,Vol 59,1964,pp.246-258.4Gloves were made from the neck and butt areas of cattlehide work-gloveleather selected for 3 of softness varying from soft to firm.These were ranked fromsoftest to firmest by 20 individuals.Since there was some overlapping of rank asassigned by individual observers,the final rank was assigned according to highestnumber of selections.Specimens of leather cut from the sides in the area from whicheach glove was cut were tested for stiffness according to this test method.At 90 oftwist,the stiffness values gave a ranking similar to that obtained by feel.Specimenscut parallel to the backbone gave more consistent ranking than specimens cutperpendicular to the backbone.This undoubtedly reflects the fact that work glovesare cut from a side with the fingers parallel to the backbone.A report of theseexperiments and data used for calculation of precision and accuracy are on file atASTM Headquarters.5The sole source of supply of the apparatus known to the committee at this timeis Taber Industries,455 Bryant Street,North Tonawanda,NY,14120.If you areaware of alternative suppliers,please provide this information to ASTM Interna-tional Headquarters.Your comments will receive careful consideration at a meetingof the responsible technical committee,which you may attend.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 be provided to indicate the