ASTM_D_4576_-_08_2013.pdf

Designation:D457608(Reapproved 2013)Standard Test Method forMold Growth Resistance of Wet Blue1This standard is issued under the fixed designation D4576;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 moldgrowth resistance of wet blue and wet white subject to storageand shipping requirements and intended for use in leathermanufacturing.This test method may not be suitable toevaluate fungicides that are inactivated by proteins.Thisincludes alkyldimethylbenzyl ammonium chlorides.1.2 Conclusions about mold growth resistance are drawnfrom the results by comparing the test with a simultaneouslyrun control of known resistance.Success or failure is deter-mined by the amount of mold growth relative to the control.1.3 To allow use of this test method by any laboratory,flexibility has been permitted in times,temperature,andhumidity of incubation,inoculum,hide sampling area,andchoice of control.These may be adjusted to fit local conditionsbut must be standardized.1.4 For mold growth resistance of wet white,the procedureis identical,substitute wet white for wet blue in the standardmethod.1.5 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.6 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.Terminology2.1 Definitions of Terms Specific to This Standard:2.1.1 wet bluehide or skin,or split of a hide or skin,tanned with basic chromium sulfate,containing approximately50%moisture and having an acidic pH.2.1.2 wet whitea hide or skin,or split of a hide or skintanned with organic or non-organic tanning agents(excludingchromium or iron containing agents and vegetable extracts),containing approximately 50%moisture.3.Summary of Test Method3.1 Wet blue test specimens are surrounded by but notcovered with agar,inoculated,and incubated.3.2 After various incubation periods,mold growth is ratedas a percentage of the wet blue surface covered by mold.3.3 Resistance to mold growth of the wet blue test specimenis determined by comparison with wet blue of known resis-tance characteristics(the control),that is tested simultaneously.4.Significance and Use4.1 This test method provides a technique for evaluatingmold growth resistance characteristics of wet blue,and shouldassist in the prediction of storage time before molding occurs.4.2 The degree of correlation between this test and commer-cial quantities of wet blue in storage or shipment situations,orboth,has not been fully determined.5.Interferences5.1 A common interference is contamination of plates,agar,or samples by unwanted organisms that settle in from theenvironment.5.2 Volatility and Leachability of BiocidesA“zone ofinhibition”where no mold grows on the agar adjacent to thespecimen indicates that the fungicide may leach.6.Apparatus6.1 Petri Dishes,120 mm diameter.Sterile plastic dispos-able dishes are preferred.6.2 Incubator,or location providing similar conditions be-ing free of drafts,and capable of a constant(6 2C)tempera-ture within the 26 to 30C range.6.3 Medicine droppers,disposable plastic type delivering 30to 35 drops per mL.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 May 2013.Originallyapproved in 1986.Last previous edition approved in 2008 as D4576-08.DOI:10.1520/D4576-08R13.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 7.Reagents and Materials7.1 Potato Dextrose Agar,2a dehydrated plating mediumused in culturing yeasts and molds from dairy products.7.2 Inoculum,3Aspergillus niger 1 106spores per mL,orother organism or a combination of organisms known to beindigenous to the storage area of the wet blue.8.Sampling,Test Specimen,and Test Units8.1 Take test specimens from equivalent hide locations(forexample,butt area)for both test and control.8.2 If unable to test immediately,hold test specimens inseparate plastic bags and keep cool.8.3 Test specimens should be a square,with a side of 25.4mm(1 in.).8.4 Use three test specimens for each test unit of wet bluesurface to be evaluated.9.Procedure9.1 Agar Preparation:9.1.1 Agar RequirementsA split wet blue test specimenrequires about 25 mL solution and an unsplit wet blue testspecimen requires about 40 mL.Calculate number of millilitresof agar required for tests to be performed,allowing 50 mL forvitality check.9.1.2 Weigh out 3.9 g p