ASTM_D_7251_-_11.pdf

Designation:D725111An American National StandardStandard Specification forColor and Appearance Retention of Variegated Color PlasticSiding Products1This standard is issued under the fixed designation D7251;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.Scope*1.1 This specification establishes requirements and testmethods for the color and appearance retention of variegatedcolor plastic siding products.1.2 Color retention testing provides a method for estimatingthe acceptability of color change in a siding product over aperiod of years of service.1.3 Characterization of color and appearance for variegatedcolors is complicated by the presence of multiple colors in arandom pattern.The procedure is based on using a template toreference six spots for color measurement.1.4 Methods of indicating compliance with this specifica-tion are provided.1.5 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.NOTE1There is no known ISO equivalent to this standard.2.Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD1435 Practice for Outdoor Weathering of PlasticsD1600 Terminology forAbbreviated Terms Relating to Plas-ticsD2244 Practice for Calculation of Color Tolerances andColor Differences from Instrumentally Measured ColorCoordinatesE805 Practice for Identification of Instrumental Methods ofColor or Color-Difference Measurement of MaterialsG147 Practice for Conditioning and Handling of Nonmetal-lic Materials for Natural and Artificial Weathering Tests3.Terminology3.1 DefinitionsDefinitions are in accordance with termi-nologies in Terminologies D883 and D1600 unless otherwisenoted.3.2 Definitions of Terms Specific to This Standard:3.2.1 color regionparameters that define the color spacefor a siding sample,measured with Hunter Units,spheregeometry(di:8),Illuminant C,2 Observer,specular compo-nent included.3.2.1.1 DiscussionThe color values used to classify colorsby region were established by measuring the Hunter L,a,bcolor values from the sample population,calculating theaverage for Hunter L,a,b,and then choosing the integer fromthe corresponding L,a,b average values(that is,by truncatingany fractional result)to be used to classify colors by region.Thus,average values greater than zero are truncated down tothe next lowest integer,and average values less than zero aretruncated up to the next highest integer.All values greater than-1 and less than+1 truncate to 0.3.2.2 color retention standardspredictive color regionsdescribed by a three dimensional model which constituteacceptable color retention levels resulting from weathering ofa specific product type and color.3.2.2.1 DiscussionColor retention standards are definedby equations that describe the three dimensional ellipsoidvalue.3.2.3 ellipsoid valuea mathematical calculation derivedby inserting the measured L,a,and b values of aweathered specimen into an ellipsoid equation.3.2.4 temperate northern climatein weathering testing,aNorth American metropolitan area testing site located within73 to 100W longitude and 37 to 45N latitude.3.2.5 variegated plastic sidingsiding having discretemarkings of different colors.4.Classification4.1 DefinitionsDefinitions are in accordance with termi-nology in Terminologies D883 and D1600 unless otherwisenoted.1This specification is under the jurisdiction of ASTM Committee D20 onPlastics and is the direct responsibility of Subcommittee D20.24 on Plastic BuildingProducts.Current edition approved April 1,2011.Published April 2011.Originallyapproved in 2006.Last previous edition approved in 2010 as D7251-10.DOI:10.1520/D7251-11.2For 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.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.2 Color RegionsThe color region for a color is deter-mined by measuring the Hunter L,a,b color values at sixlocations on each specimen in a sample population andcalculating the average Hunter L,a,b color value.Use theinteger value(by truncating any fractional result)of theaverage to determine the color region for the color using thefollowing region boundaries.4.2.1 Region 1BrownL=20 to 49L=25 to 49a=1 to 5a=8 to 5b=2 to 11b=12 to 254.2.2 Region 2Medium BlueL=45 to 64a=26 to 1b=25 to 24.2.3 Region 3Light BlueL=65 to 93a=12 to 1b