ASTM_D_358_-_98_2012e1.pdf

Designation:D35898(Reapproved2012)1Standard Specification forWood to Be Used as Panels in Weathering Tests ofCoatings1This standard is issued under the fixed designation D358;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 Department of Defense.1NOTECorrections to the unit conversion for 10 mm were made in July 2012.1.Scope1.1 This specification designates woods for weathering testsof exterior solvent-borne or water-borne paints and othermaterials of similar purpose.Such tests may include eitheroutdoor exposure tests or accelerated laboratory tests.It is thepurpose of this specification to minimize the influence ofvariation of wood of a given species on test results.1.2 The values stated in SI units are to be regarded asstandard.The values given in parentheses are for informationonly.2.Referenced Documents2.1 ASTM Standards:2D3924 Specification for Environment for Conditioning andTesting Paint,Varnish,Lacquer,and Related Materials3.General Considerations3.1 A variety of different species should be used for testingfinishes because of the wide variations in the anatomy and thedensity between wood species.These factors have tremendousinfluences on finish performance.Latewood band width anddensity are especially important to finish performance,andthese parameters vary significantly between wood species.Cedar and redwood have relatively low proportions of hardsummerwood distributed in narrow bands and contain extrac-tives that discolor some paint films.Southern pine has a largeproportion of hard summerwood in wide bands.3.2 The angle between the growth rings and the surface ofthe specimen is very critical to finish performance.Commer-cial practice utilizes the following classification system.Boards in which growth forms an angle of less than 30 withthe wide surface of the piece are said to be flat-sawn orflat-grained;those with the rings intersecting at angles between30 and 60 are termed bastard-sawn;and those with anglesgreater than 60 are termed quarter-sawn,edge grain,orvertical grain.3.3 Some industrial processors of wood products may uti-lize wood at moisture levels significantly higher than theequilibrium moistures cited in this specification.In thesespecific cases,appropriately higher moisture content panelsmay be prepared for testing of factory applied finishes.WESTERN RED CEDAR4.Species4.1 The material for test panels shall be western red cedar(Thuja plicata).5.Weight per Volume5.1 When the wood is in equilibrium with air at 60 to 65%relative humidity and 21 6 0.5C(70 6 1F)it shall weigh 350to 370 kg/m3(22 to 23 lb/ft3)or at 50 6 5%relative humidityand 23 6 2C(73.5 6 3.5F),which are specified inSpecification D3924 as standard conditions for testing paintand related coatings,it shall weigh 343 to 359 kg/m3(21.4 to22.4 lb/ft3).NOTE1The density requirement is to eliminate wood specimens thatvary greatly from the average for that species.Either set of conditions maybe used to establish the density.At 60 to 65%relative humidity wood hasa moisture content of approximately 12%while at 45 to 55%relativehumidity it contains 9 to 10%.The former is closer to the moisturecontent of wood exposed to most exterior climatic conditions.6.Character of Wood6.1 The wood shall be heartwood having edge grain andshall be free of knots and other defects.The color of the woodshall be uniform across each panel with no streaks that areexcessively light or dark.The number of annual growth ringsper inch along the radius of the log from which the wood wasobtained shall not be less than ten.The surfaces shall be1This specification is under the jurisdiction of ASTM Committee D01 and is thedirect responsibility D01.42 on Architectural Coatings.Current edition approved July 1,2012.Published August 2012.Originallyapproved in 1933.Last previous edition approved in 2006 as D358 98(2006).DOI:10.1520/D0358-98R12E01.2For 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 StatesNOTICE:This standard has either been superseded and replaced by a new version or withdrawn.Contact ASTM International(www.astm.org)for the latest information1smoothly planed and sanded thoroughly with 150 grit sandpa-per within two weeks of testing.7.Thickness of Panels7.1 The minimum thicknesses(Note 2)in proportion towidth(across the grain)shall be as follows:Panel Width,mm(in.)Minimum Thickness,mm(in.)Less than 75(less than 3)10(1332)75 to 150(3 to 6)11(716)Over 150(over 6)19(34)NOTE2Minimum th