1、Designation: D 7251 06e1An American National StandardStandard Specification forColor and Appearance Retention of Variegated Color PlasticSiding Products1This standard is issued under the fixed designation D 7251; the number immediately following the designation indicates the year oforiginal adoption
2、 or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTEFig. 1 was editorially revised in September 2006.1. Scope1.1 This specification e
3、stablishes 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 a
4、nd appearance for variegatedcolors is complicated by the presence of multiple colors in arandom pattern. The procedure is based on using a template toreference 6 spots for color measurement.1.4 Methods of indicating compliance with this specifica-tion are provided.1.5 This standard does not purport
5、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.NOTE 1There is no known ISO equivalent to this sta
6、ndard.2. Referenced Documents2.1 ASTM Standards:2D 883 Terminology Relating to PlasticsD 1435 Practice for Outdoor Weathering of PlasticsD 1600 Terminology for Abbreviated Terms Relating toPlasticsD 2244 Practice for Calculation of Color Tolerances andColor Differences from Instrumentally Measured C
7、olorCoordinatesE 805 Practice for Identification of Instrumental Methods ofColor or Color-Difference Measurement of MaterialsG 147 Practice for Conditioning and Handling of Nonme-tallic Materials for Natural and Artificial Weathering Tests3. Terminology3.1 DefinitionsDefinitions are in accordance wi
8、th termi-nologies in Terminologies D 883 and D 1600 unless otherwisenoted.3.2 Definitions of Terms Specific to This Standard:3.2.1 color regionparameters that define the color spacefor a siding measured with Hunter Units, Illuminant C, 2Observer, specular component included.3.2.1.1 DiscussionThe col
9、or values used to classify colorsby region will be 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, no roundingup or down) to be used to
10、classify colors by region.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
11、that describe the three dimensional ellipsoidvalue.3.2.3 ellipsoid valuea mathematical calculation derivedby inserting the measured DL, Da, and Db values of aweathered specimen into an ellipsoid equation.3.2.4 variegated plastic sidingsiding having discretemarkings of different colors.4. Classificat
12、ion4.1 DefinitionsDefinitions are in accordance with termi-nology in Terminologies D 883 and D 1600 unless otherwisenoted.4.2 Color RegionsThe color region for a color is deter-mined by measuring the Hunter L, a, b color values for asample population and calculating the average Hunter L, a, bcolor v
13、alue. Use the integer value (by truncating any fractionalresult) of the average to determine the color region for the colorusing the following region boundaries.4.2.1 Region 1BrownL = 20 to 491This specification is under the jurisdiction of ASTM Committee D20 onPlastics and is the direct responsibil
14、ity of Subcommittee D20.24 on Plastic BuildingProducts.Current edition approved April 1, 2006. Published April 2006.2For 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
15、the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.a=1to5b=2to114.2.2 Region 2Medium BlueL = 45 to 64a=8to1b = 12 to 24.2.3 Region 3Light BlueL = 65 to 89a=8to1b = 12 to 24.2.4 Regi
16、on 4GreenL = 50 to 84a = 12 to 1b=1to104.2.5 Region 5Medium BeigeL = 50 to 74 L = 50 to 64 L = 65 to 74a=0to1 a=2to1 a=7to0b=4to12 b=11to14 b=11to124.2.6 Region 6Light BeigeL = 75 to 84 L = 85 to 93 L = 75 to 84a=0to1 a=7to1 a=7to1b=4to12 b=4to12 b=11to124.2.7 Region 7GoldL = 65 to 93a=0to4b=13to304
17、.2.8 Region 8YellowL = 65 to 93a = 10 to 1b=13to304.2.9 Region 9WhiteL = 85 to 100 All L = 94 to 100a=2to1b=1to34.2.10 Region 10Light GrayL = 65 to 84a=0to1b=1to34.2.11 Region 11MauveL = 65 to 93 L = 65 to 93 L = 50 to 64a=2to11 a=5to11 a=2to11b=2to12 b=13to15 b=2to154.2.12 Region 12Medium GrayL = 5
18、0 to 64a=0to1b=1to34.2.13 Region 13Dark GrayL = 25 to 49a=1to5b=1to14.2.14 Region 14Dark BlueL = 25 to 44a=8to3b = 12 to 24.2.15 Region 15Dark GreenL = 25 to 49a = 20 to 2b=1to114.2.16 Region 16Dark RedL = 25 to 49a=6to30b=1to254.3 Ellipsoid Value EquationsUse the following equationsto determine the
19、 ellipsoid value representing the change incolor due to weathering. Use the equation that corresponds tothe color region determined for the specimens initial color(prior to weathering) in 4.2.4.3.1 Region 1BrownDL 1.6!25.2!21Da 1 1.0!23.0!21Db 0.5!22.5!25 Ellipsoid Value4.3.2 Region 2Medium BlueDL 1
20、 1.0!26.0!21Da 1 0.6!22.9!21Db 0.8!25.4!25 Ellipsoid Value4.3.3 Region 3Light BlueDL 1 0.3!26.4!21Da 1 0.1!22.7!21Db 0.8!24.3!25 Ellipsoid Value4.3.4 Region 4GreenDL 0.2!25.9!21Da 0.8!24.8!21Db 0.2!25.6!25 Ellipsoid Value4.3.5 Region 5Medium BeigeDL 1 0.1!26.1!21Da 0.0!22.8!21Db 0.4!23.9!25 Ellipsoi
21、d Value4.3.6 Region 6Light BeigeDL 0.0!25.0!21Da 0.2!22.6!21Db 0.3!25.4!25 Ellipsoid Value4.3.7 Region 7GoldDL 1 0.6!26.6!21Da 1 0.3!23.4!21Db 1 0.4!24.7!25 Ellipsoid Value4.3.8 Region 8YellowDL 1 0.3!25.5!21Da 1.0!23.3!21Db 1 0.1!25.5!25 Ellipsoid Value4.3.9 Region 9WhiteDL 0.6!28.2!21Da 1 0.0!23.3
22、!21Db 1.9!25.3!25 Ellipsoid Value4.3.10 Region 10Light GrayDL 1 1.8!27.0!21Da 0.2!22.1!21Db 1.3!24.0!25 Ellipsoid Value4.3.11 Region 11MauveDL 0.4!26.5!21Da 0.8!24.0!21Db 1.1!24.5!25 Ellipsoid Value4.3.12 Region 12Medium GrayDL 1 1.0!26.6!21Da 1 0.3!22.5!21Db 1.2!23.7!25 Ellipsoid Value4.3.13 Region
23、 13Dark GrayDL 0.1!25.1!21Da 1 0.8!23.4!21Db 1 0.1!23.0!25 Ellipsoid ValueD725106e124.3.14 Region 14Dark BlueDL 0.3!25.2!21Da 1.0!23.6!21Db 1 1.3!24.5!25 Ellipsoid Value4.3.15 Region 15Dark GreenDL 0.0!25.0!21Da 1 0.4!23.0!21Db 1 0.2!23.8!25 Ellipsoid Value4.3.16 Region 16Dark RedDL 0.4!25.4!21Da 0.
24、8!24.0!21Db 0.2!23.0!25 Ellipsoid Value5. Procedure for Measuring Color Retention5.1 Test Site Setup and Exposure Duration Test Times:5.1.1 Samples shall be exposed at three test sites: TemperateNorthern represented by a site located in Louisville, KY orCleveland, OH; hot, humid represented by a sit
25、e located inMiami, FL, and hot, dry represented by a site located inPhoenix, Arizona. Additional test sites are permitted as agreedupon by the buyer and the seller.5.1.2 All exposures shall be conducted at an angle of 45facing South and backed using unpainted plywood in accor-dance with Practices D
26、1435 and G 147.5.1.3 Remove test specimens for color measurement at24-month exposure. In some cases, 24 months are not sufficientto distinguish material durability differences and longer expo-sure periods are necessary. Additional exposure times arepermitted as agreed upon by the buyer and the selle
27、r.5.2 Sampling and Specimen Preparation:5.2.1 Samples shall be representative of the product to beevaluated.NOTE 2Samples prepared in the laboratory in the same manner ascommercial samples are an acceptable alternate to a commercial part. Ifthe commercial product is extruded, the laboratory specimen
28、 must beextruded; if the commercial product is injection molded, the laboratoryspecimen must be injection molded, and so forth.5.2.2 Select a minimum of four specimens per sample pertest site to allow for three test specimens and one file specimenfor each sample evaluated.5.2.3 The file specimen wil
29、l be used for a visual assessmentof variegation/contrast change. The test specimens will bemeasured for color and weathered.5.2.4 Specimens shall be a flat section and a minimum of 3by 10 in. (76 by 254 mm). The variegated pattern shall beparallel to the long edge of the specimen.5.2.5 Use the Varie
30、gated Color Measurement Template toidentify the 6 spots on each test specimen for color retentiontesting. The center points of these 6 spots are specified in Fig.1. The diameter of the six spots is specified as 0.50 in. (12.2mm) minimum. Those shown in the diagram are for illustrationonly.5.2.6 The
31、exact locations of these test spots must bedetermined and recorded for each test specimen to allowmeasurement of color change following exposure testing.5.2.7 The locations and spot sizes identified in 5.2.5 for eachtest specimen shall not change once the exposure test is started.5.2.8 Mark each spe
32、cimen permanently to ensure retentionof identity during and after exposure testing.NOTE 3Use of a vibratool leaves a permanent mark that satisfies thiscriteria.5.3 Data Record:5.3.1 Measured specimen color values shall be reported toone decimal place.5.3.2 Calculation of color units shall be reporte
33、d to onedecimal place.5.4 Practice:5.4.1 Obtain test and file specimens in accordance with 5.2.5.4.2 Measure the original tristimulus X, Y, and Z values forthe 6 spots identified in 5.2.5 for each test specimen. Color ismeasured using sphere geometry (D8), illuminant C, 2 ob-server, specular compone
34、nt included in accordance with Prac-tice E 805. The minimum aperture size for color measurement0.50 in. (12.2 mm).5.4.3 Calculate the Hunter L, a, and b units in accordancewith the equations in the section on “Hunter L, a, and b ColorSpace and Color-Difference Equation” in Test Method D 2244using th
35、e average of the six measurements and record in apermanent record.5.4.4 The measured average color of each test specimen isthe specimens initial color and is used to determine colorchange after specified periods of exposure testing.5.4.5 Repeat steps 5.4.2 through 5.4.4 for each test speci-men.5.4.6
36、 Calculate the average color in Hunter L, a, b for thetest specimens to determine their color region as defined in 4.2.5.4.6.1 Calculate the overall average color of the 3 testspecimens for each test site from step 5.4.5.5.4.6.2 If the color regions determined for each test site arenot the same, re-
37、measure the test specimens for the non-conforming test site. If the three test sites still do not agree,calculate the overall average color for test specimens from allsites to determine the samples color region.5.4.7 Expose the test specimens at the test sites in accor-dance with 5.1.1 and 5.1.2. Re
38、cord in a permanent record thetest start date.5.4.8 Remove the test specimens at the exposure interval(s)in accordance with 5.1.3. Record in a permanent record thedate the specimens are removed from the exposure test rack forcolor measurement.5.4.9 The exposed test specimens shall be measured forcol
39、or and evaluated for appearance. It is recommended thatcolor measurement and appearance evaluation be conducted atthe test site. Color measurement shall take place within sevendays of specimen removal from the exposure test rack. It isrecommended that color measurement take place within 48 h ofthe s
40、pecimens removal from the exposure test rack.NOTE 4Additional color development is known to occur for PVCproducts after removal from exposure to ultraviolet (UV) light. Thisartificial color change is referred to as Dark Time Yellowing. Colormeasurement within 48 h of removal is strongly recommended
41、for PVCproducts.5.4.10 Wash the exposed test specimens in accordance withthe procedure in Annex A1.5.4.11 Inspect each exposed test specimen for appearanceand surface condition. Record observations and inspection datein a permanent record.D725106e135.4.12 Referencing the file specimen, evaluate each
42、 testspecimen for loss of variegation in accordance with 6.3.5.4.13 Measure and record the color of each test specimenin accordance with 5.4.2 through 5.4.3 for each exposure time.Record in a permanent record the date the color of thespecimen(s) is measured.5.4.14 Referencing each test specimens ini
43、tial color deter-mined in 5.4.5, calculate and record the color change in HunterL, a, and b units for each test specimen.5.4.15 In cases where specimens are evaluated at exposuretimes other than 24 months, the specimens shall be returned tothe exposure test rack within 7 days for continuation of the
44、 test;it is recommended the samples be returned to the test rackswithin 48 h. Record in a permanent record the date thespecimens are returned to the exposure test rack.NOTE 5In case of dispute, the referee procedure shall be the use ofseparate specimens for each exposure time that can then be dispos
45、ed aftercolor measurements are made.6. Performance Requirements6.1 Using the ellipsoid value equations in 4.3, calculate theellipsoid value for a test specimen using the measured colorchange determined in 5.4.14 and the appropriate color regiondetermined in 4.2.6.2 Acceptable color retention is dete
46、rmined by the averageellipsoid value of the three test specimens being less than orequal to 1.0. This value shall be calculated for each test site andexposure time. In addition, no individual specimen shall havean ellipsoid value of greater than 1.4.6.3 Acceptable variegation change is presence of v
47、ariega-tion. Failure is defined as complete loss of variegation and thepresence of a uniform color.FIG. 1 Variegated Color Measurement TemplateD725106e146.4 The specimen shall be free of any visual surface orstructural changes such as peeling, chipping, cracking, flaking,and pitting when tested in a
48、ccordance to Section 5, Procedurefor Measuring Color Retention.ANNEX(Mandatory Information)A1. WASHING WEATHERING SPECIMENSA1.1 ScopeA1.1.1 This procedure describes a practice for washingweathering specimens prior to instrumental color measure-ment. The procedure is intended to minimize any effects
49、ofaltering the specimens surface in other than a predictablemanner.A1.2 EquipmentA1.2.1 Mild Detergent,A1.2.2 Sponge, or soft cloth.A1.3 ProcedureA1.3.1 Flush exposed specimen with water.A1.3.2 Gently wash the specimen with a dilute solution(1 % by weight in water, maximum concentration) of a milddetergent using a sponge or soft cloth.A1.3.3 The wash
