ASTM_D_8042_-_18.pdf

Designation:D804218Test Method forShrinkage Temperature of Wet Blue and Wet White1This standard is issued under the fixed designation D8042;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.1.Scope1.1 This test method covers the determination of the shrink-age temperature of all types of Wet Blue and Wet White.Theheating medium is water when the shrinkage temperature is ator below 98C.The heating medium is a glycerine-watersolution when the shrinkage temperature is above 98C.1.2 The values stated in SI units are to be regarded as thestandard.The values in parentheses are for information 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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D1517 Terminology Relating to LeatherD6076 Test Method for Shrinkage Temperature of Leather3.Terminology3.1 DefinitionsFor definitions of general leather termsused in this test method,refer to Terminology D1517.3.2 Definitions of Terms Specific to This Standard:3.2.1 shrink,vto contract or become smaller.3.2.2 shrinkage,nthe temperature at which noticeableshrinkage occurs when a Wet Blue or Wet White specimen isgradually heated in an aqueous medium.4.Summary of Test Method4.1 A Wet Blue or Wet White specimen is thoroughlysoaked in the aqueous medium that will be used to heat thespecimen for this test method.This specimen is then fastenedbetween two clamps(one fixed and one movable)and im-mersed in the aqueous medium(see Fig.1).The aqueousmedium is gradually heated until the specified temperature isreached without shrinkage or until shrinkage is indicated by adeflection of the dial needle which is attached to the movableclamp.5.Significance and Use5.1 This test method is designed to determine the tempera-ture at which the Wet Blue or Wet White specimen experiencesshrinkage.In this test method,shrinkage occurs as a result ofhydrothermal denaturation of the collagen protein moleculeswhich make up the fiber structure of the Wet Blue or WetWhite.The shrinkage temperature of Wet Blue or Wet White isinfluenced by many different factors,most of which appear toaffect the number and nature of crosslinking interactionsbetween adjacent polypeptide chains of the collagen proteinmolecules.The value of the shrinkage temperature of Wet Blueor Wet White is commonly used as an indicator of the type oftannage or the degree of tannage,or both,of that particular WetBlue or Wet White(especially for the more hydrothermallystable tannages such as chrome tannage).6.Apparatus6.1 Stand,for supporting the testing equipment.6.2 Indicating Device,either of the two devices listed asfollows:1This test method is under the jurisdiction of ASTM Committee D31 on Leatherand is the direct responsibility of Subcommittee D31.02 on Wet Blue.Current edition approved Sept.1,2018.Published October 2018.Originallyapproved in 2016.Last previous edition approved in 2016 as D8042-16.DOI:10.1520/D8042-18.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1 6.2.1 Theis Shrinkage Meter Diala dial indicator having aface divided into 360 to 380,with one revolution of the dialhand corresponding to 12.7 mm(0.5 in.)of specimenmovement,and with leeway for four revolutions of the dialhand.36.2.2 AGD(American Gage Design)Dial Indicator,a me-chanical device capable of registering on a scale a reading ofthe shrinkage or swelling movement of the specimen in a ratioof at least 25 units of dial movement(or greater)to 1 unit ofspecimen movement,and shall accurately detect by movementof the dial needle the point at which shrinkage begins.Theindicator shall have a spindle capable of attachment to thespecimen