ASTM_D_7476_-_08_2013.pdf

Designation:D747608(Reapproved 2013)Standard Test Method forBrine Saturation Value of Cured(Salt-Preserved)Hides andSkins1This standard is issued under the fixed designation D7476;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 estimation of degree ofsaturation of the brine content of cured(salt-preserved)hidesand skins containing 40%or more moisture.1.2 The values stated in inch-pound units are to be regardedas the standard.The values given in parentheses are 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:2,3D6715 Practice for Sampling and Preparation of Fresh orSalt-Preserved(Cured)Hides and Skins for Chemical andPhysical TestsE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 Definitions:3.1.1 The terms and definitions employed within this testmethod are commonly used in normal laboratory practice andrequire no special comment.4.Summary of Test Method4.1 The moisture(volatile matter by oven drying)and ashcontent of a composite hide or skin sample are determined.Forpurposes of calculation the ash is assumed to be equivalent tosodium chloride and the moisture is assumed to be equivalentto water.The percent ratio of ash to moisture is calculated.Thisratio times 100 is divided by 35.9(which is the percent salt tomoisture ratio in a saturated sodium chloride(brine)solution at20C(68F)to estimate the percent of saturation in the brinesolution in the hides or skins.NOTE1A saturated solution of sodium chloride at 20C(68F)contains 26.4%by weight of NaCl.Therefore,in 100 g of that saturatedsolution only 73.6 g(100 26.4 g)is contributed by water.As such on aweight basis,100 parts by weight of water will dissolve 35.9 parts(100 x 26.4)/73.6 by weight of NaCl.5.Significance and Use5.1 This test method is intended to evaluate whether suffi-cient salt(NaCl)has been retained by the hides or skins to slowdown degradation by bacterial(enzymatic)action,and to slowdown autolysis by inherent enzymatic action,until they arepreserved by a tanning process.NOTE2Osmosis occurs during brine curing because moisture isdrawn out by salt through the epidermis.4Low moisture(40%)in thehides does not necessarily indicate poor cure.A hide may have lowmoisture due to osmosis;to increased fat content;or to drying outconditions.In all instances the hides would still show adequate cure if themoisture was saturated to approximately 85%salt,because the ash:moisture ratio would be adequate.6.Apparatus6.1 Crucible,30 to 50 mL,high-form,platinum or porce-lain.Prepare crucible by heating it for 15 min in a mufflefurnace set at 600 6 25C.Cool in a desiccator before use.6.2 Electric Muffle Furnace,with controller or rheostat andpyrometer,capable of maintaining a temperature of 650 625C.6.3 Desiccator,of appropriate size and charged with freshdesiccant.6.4 Analytical Balance,capable of weighing to 0.001 g.6.5 Oven,forced air,capable of maintaining 100 105C.7.Reagents and Materials7.1 Distilled or de-ionized water.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 May 1,2013.Published July 2013.Originally approvedin 2008.Last previous edition approved in 2008 as D7476-08.DOI:10.1520/D7476-08R13.2For 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.3“Trade Practices for Proper Packer Cattlehide Delivery,”issued by LeatherIndustries of America and U.S.Hide,Skin&Leather Association(printed May1985).4JALCA,1963,p.143.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 8.Hazards8.1 The crucibles will be extremely hot when they areremoved from the muffle furnace.Therefore,it is suggestedthat the analyst handle the hot crucibles using furnace tongs orequivalent.9.Sampling9.1 Sampling shall be per Practice D6715.9.2 Time is crucial in the preparation of salt-preserved hidesfor chemical testing.Samples should not be prepared ifanalysis can not be done immediately.The following proce-dures should be executed with a minimum of hide exposure toeither air or moisture or salt-absorbent materials(includinghuman skin).