ASTM_D_6408_-_99_2020.pdf

Designation:D640899(Reapproved 2020)Standard Test Method forAnalysis of Tannery Liquors1This standard is issued under the fixed designation D6408;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 analysis of tannery liquorsmade up from vegetable tanning materials.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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:2D4903 Test Method for Total Solids and Water in VegetableTanning Material ExtractsD4904 Practice for Cooling of Analytical SolutionsD6401 Test Method for Determining Non-Tannins and Tan-nin in Extracts of Vegetable Tanning MaterialsD6402 Test Method for Determining Soluble Solids andInsolubles in Extracts of Vegetable Tanning MaterialsD6404 Practice for Sampling Vegetable Materials Contain-ing TanninD6410 Test Method for Determining Acidity of VegetableTanning Liquors2.2 ALCA Methods:A25 Analysis of Tannery Liquors33.Terminology3.1 Definitions:3.1.1 tannery liquorwater solutions containing vegetabletannin that are made up and used in a vegetable tannery.3.1.2 tanninan astringent substance found in the variousparts of plants such as bark,wood,leaves,nuts,fruits,roots,etc.Also,quantitatively,tannins are operationally defined asthe non-volatile materials present in tannin extracts and raw orspent materials that are dissolved or suspended in water,arepart of the soluble solids determined by Test Method D6402,and do react with or bind to hide powder when mixed as in thistest method.3.1.3 vegetable tanninsmixtures of substances(naturalproducts)obtained from plant tissues by water extractionwhich have the chemical and physical properties necessary toconvert animal hides and skins into leather.4.Summary of Test Method4.1 An analytical solution is prepared from the sample oftannery liquor(Practice D6404).Specimen aliquots from thisanalytical solution are then analyzed for total solids(TestMethod D4903),soluble solids and insolubles(Test MethodD6402),non-tannins and tannin(Test Method D6401),andtotal acidity(Test Method D6410).5.Significance and Use5.1 This test method is used to determine the chemicalproperties of tannery liquors which are relevant for thevegetable tanning process and influence the astringency ofvegetable tanning liquors.The astringency of liquors is depen-dent upon the solids and tannin content and the acidity.Thismethod provides a standard procedure for determining theseproperties for any sample of vegetable tanning liquor.5.2 The specimens are aliquots from the analytical solutionprepared from the sample of tannery liquor collected for thispurpose.1This test method is under the jurisdiction of ASTM Committee D31 on Leatherand is the direct responsibility of Subcommittee D31.01.This test method has beenadapted from and is a replacement for Method A25 of the Official Methods of theAmerican Leather Chemists Association.Current edition approved Dec.1,2020.Published December 2020.Originallyapproved in 1999.Last previous edition approved in 2014 as D6408 99(2014).DOI:10.1520/D6408-99R20.2For 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.3Official Methods of the American Leather Chemists Association.Availablefrom the American Leather Chemists Association,University of Cincinnati,P.O.Box 210014,Cincinnati,OH 45221-0014.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.15.3 The total solids,soluble solids,and non-tannins contentare determined and then the tannin content of the liquor sampleis calculated.Because the amount of tannin per liter ofanalytical solut