1、Designation: D7856 15aStandard Specification forColor and Appearance Retention of Solid and VariegatedColor Plastic Siding Products using CIELab Color Space1This standard is issued under the fixed designation D7856; the number immediately following the designation indicates the year oforiginal adopt
2、ion 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 colo
3、r and appearance retention of solid andvariegated colored plastic siding products.1.2 Color retention testing provides a method for estimatingthe acceptability of color change in a plastic siding productover an extended period of service.NOTE 1The exposure locations and durations specified in thisst
4、andard have been shown to provide a good estimation of the colorchange in vinyl and polypropylene siding products over an extendedperiod of service (see 2.2). It is expected that materials designed for theexposure conditions typical of exterior siding will respond similarly, butthe applicability of
5、this standard to other types of plastic siding has notbeen empirically established.1.3 This specification is a successor to Specifications D6864and D7251, which cover solid colors and variegated colors,respectively. This specification combines coverage for both,and has the same scope as those standa
6、rds.1.4 Specifications D6864 and D7251 use Hunter Lab colorspace for measurement of colors and evaluation of colorchange. These standards require classification of colors intoregions based on the L, a, and b coordinates of the color, andevaluation of color changes is done using an ellipsoid valueequ
7、ation having unique coefficients for each color region. Thisspecification uses CIE 1976 L* a* b* color space for measure-ment and evaluation of color change. Using this method, theneed for separate color regions and evaluation equations hasbeen eliminated.1.5 Provisions for sample selection and prep
8、aration, andweathering are the same in this specification as in Specifica-tions D6864 and D7251.1.6 Characterization of color and appearance for variegatedcolors is complicated by the presence of multiple colors in arandom pattern. The procedure for measuring variegated colorsin this specification i
9、s based on using a template to referencesix spots for color measurement.1.7 This standard specifies outdoor weathering in threespecific climate zones for a single 24-month exposure, and thecolor retention performance requirements under these condi-tions are established to be indicative of acceptable
10、 performanceover an extended period of service. However, nothing in thisstandard precludes the use of different or additional climatezones, or different exposure durations, so long as thoseconditions are clearly specified in any reports.1.8 UnitsThe values stated in inch-pound units are to beregarde
11、d as standard. The values given in parentheses aremathematical conversions to SI units that are provided forinformation only and are not considered standard.1.9 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user o
12、f this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE 2There is no known ISO equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:2D660 Test Method for Evaluating Degree of Checking ofExteri
13、or PaintsD661 Test Method for Evaluating Degree of Cracking ofExterior PaintsD662 Test Method for Evaluating Degree of Erosion ofExterior PaintsD714 Test Method for Evaluating Degree of Blistering ofPaintsD772 Test Method for Evaluating Degree of Flaking (Scal-ing) of Exterior PaintsD883 Terminology
14、 Relating to PlasticsD1435 Practice for Outdoor Weathering of PlasticsD1600 Terminology forAbbreviated Terms Relating to Plas-tics1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.24 on Plastic BuildingProducts.Current e
15、dition approved Dec. 1, 2015. Published December 2015. Originallyapproved in 2014. Last previous edition approved in 2015 as D7856 15.DOI:10.1520/D7856-15A.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of AST
16、MStandards 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 States1D2244 Practice for Calcula
17、tion of Color Tolerances andColor Differences from Instrumentally Measured ColorCoordinatesD4214 Test Methods for Evaluating the Degree of Chalkingof Exterior Paint FilmsD6864 Specification for Color and Appearance Retention ofSolid Colored Plastic Siding ProductsD7251 Specification for Color and Ap
18、pearance Retention ofVariegated Color Plastic Siding ProductsE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE1331 Test Method for Reflectance Factor and Color bySpectrophotometry Using Hemispherical GeometryG147 Practice for Conditioning and Handlin
19、g of Nonmetal-lic Materials for Natural and Artificial Weathering Tests2.2 Other Reference:VS2W Vinyl Siding Institute (VSI) Technical Research Re-port for Weatherability of Vinyl Siding Products3NOTE 3The report cited in 2.2 supports the conclusion that commer-cial vinyl siding products which demon
20、strate weathering behavior withinconformance to these standards during a two year test program are likelyto provide acceptable color retention properties over an extended period ofservice. Unpublished long term weathering study data support a similarconclusion for polypropylene siding (see Appendix
21、X1).3. Terminology3.1 DefinitionsDefinitions are in accordance with Termi-nologies D883 and D1600 unless otherwise noted.3.2 Definitions of Terms Specific to This Standard:3.2.1 polypropylene sidinga shaped material, made prin-cipally from polypropylene homopolymer, or copolymer,which in some cases
22、may contain fillers and/or reinforcements,that is used to clad exterior walls of buildings.3.2.2 temperate northern climatein weathering testing, aNorth American metropolitan area testing site within 73 to100W longitude and 37 to 45N latitude.3.2.3 variegated plastic sidingsiding having discretemark
23、ings of different colors.3.2.4 vinyl sidinga shaped material, made principallyfrom rigid poly(vinyl chloride) (PVC), that is used to cladexterior walls of buildings.4. Significance and Use4.1 This specification uses two-year outdoor weathering toprovide an indication of the long-term color retention
24、 proper-ties of plastic siding samples.4.2 The methodology and procedures prescribed are onlyapplicable to this specification.4.3 The exposure locations and durations specified in thisstandard have been shown to provide a good estimation of thecolor change in vinyl and polypropylene siding products
25、overan extended period of service (see 2.2). It is expected thatmaterials designed for the exposure conditions typical ofexterior siding will respond similarly, but the applicability ofthis standard to other types of plastic siding has not beenempirically established.4.4 The response of siding color
26、 samples to outdoor expo-sure is sensitive to differences in weather, and is subject tovariation from year to year. Differences in exposure andweather patterns, including temperature, moisture, total radiantenergy, and type and concentration of pollutants, also affectresponse in different climates.
27、For this reason, samples areweathered in three distinct North American locations. Samplesmust show acceptable weathering performance at all threelocations.4.5 It has been shown (see 2.2) that most color changeoccurs during the first two years of outdoor exposure. Afterapproximately two years, the ra
28、te of change levels off, and thedegree of change observed after two years provides a signifi-cant indication of the overall degree of change that will bepresent through subsequent long term exposure.4.6 Studies involving vinyl siding and polypropylene sidingsupport the applicability of the methods a
29、nd criteria in thisstandard to plastic siding. As essentially all plastic siding useseither vinyl or polypropylene, no comparable studies of sidingusing polymers other than these two have been identified.4.7 No method that is subject to the vagaries of outdoorweather can be expected to absolutely pr
30、edict the degree ofcolor change at a specific point in the future. However, theabove results show that acceptability of color change measuredafter two-years of outdoor exposure correlates sufficiently tothe long term acceptability to provide an indication of thecommercial viability of a color for lo
31、ng term use on customersbuildings, which is the purpose of this specification.4.8 Criteria for acceptability were developed by correlatingthe results of visual evaluation of various colors and colordifferences to the measured degrees of color difference. Thusthe performance requirements in Section 7
32、 represent the humanperception of the limits of acceptability of a measured colorchange.5. Sampling and Specimen Preparation5.1 Samples shall be representative of the product to beevaluated. Samples shall be taken either from commercialproducts or from laboratory samples. Laboratory samples shallbe
33、produced in the same manner as the commercial products tobe evaluated.NOTE 4Production of laboratory samples in the same manner includesuse of the same method of forming the product. For example, if thecommercial product is extruded, the laboratory specimen shall be ex-truded; if the commercial prod
34、uct is injection molded, the laboratoryspecimen shall be injection molded, and so forth.5.2 Mark each specimen permanently to ensure retention ofidentity during and after exposure testing. Ensure that theidentification marking is small and does not interfere with thecolor measuring area.NOTE 5Use of
35、 a vibratool leaves a permanent mark that satisfies thiscriterion.5.3 Solid Color Specimens:3Available from Vinyl Siding Institute (VSI), National Housing Center, 120115th Street NW, Suite 220, Washington, DC 20005, http:/www.vinylsiding.org.D7856 15a25.3.1 Prepare a minimum of four specimens per sa
36、mple pertest site to allow for three test specimens and one file specimenfor each sample evaluated.5.3.2 The file specimen will be measured for color at eachtest location and will serve as the reference color for evaluationof color changes in the three replicates after weathering.5.3.3 Specimens sha
37、ll be a flat section and a minimum of 2by 334 in. (51 by 95 mm). If the normally-exposed surface ofthe siding is heavily textured to the extent that correct orconsistent color measurements cannot be obtained, weatheringtest exposure of the back surface or other surface is permitted,so long as the su
38、rface is representative of the exposed surface.5.4 Variegated Color Specimens:5.4.1 Prepare a minimum of four specimens per sample pertest site to allow for three test specimens and one file specimenfor each sample evaluated.5.4.2 The file specimen will be used for a visual assessmentof variegation/
39、contrast change. The test specimens will bemeasured for color and weathered.5.4.3 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.5.4.4 Use the Variegated Color Measurement Template toidentify the
40、six spots on each test specimen for color retentiontesting. The center points of these six spots are specified in Fig.1. The diameter of the six spots is specified as 0.50 in. (12.2mm) minimum. The actual diameter used shall be large enoughto admit the aperture plate of the instrument used withoutex
41、traneous light leakage.5.4.5 The exact locations of these test spots must bedetermined and recorded for each test specimen to allowmeasurement of color change following exposure testing. TheFIG. 1 Variegated Color Measurement TemplateD7856 15a3locations and spot sizes identified in 5.4.4 for each te
42、stspecimen shall not change once the exposure test is started.6. Procedure6.1 Outdoor Weathering:6.1.1 Samples shall be exposed at three test sites: TemperateNorthern represented by a site located in near Louisville, KYorCleveland, OH; hot, humid represented by a site located nearMiami, FL; and hot,
43、 dry represented by a site located nearPhoenix, AZ. Actual test locations are not limited to theserepresentative cities so long as the location is representative ofthe indicated climate zone.6.2 Color Measurement (General):6.2.1 All color measurements are to be made in accordancewith this section. O
44、btain test and file specimens in accordancewith 5.3 or 5.4. The following procedure is used at each of thethree weathering locations.6.2.2 Color is measured using 8 sphere geometry, diffuseillumination, specular component included (di:8), IlluminantD65, and 10 observer, in accordance with Test Metho
45、d E1331.For solid colors make at least three separate measurements onthe specimen and average them. For variegated colors take onereading at each of the six spots identified in 5.4.4, and averagethem.6.2.3 Calculate the CIE 1976 L*a*b* units in accordancewith the “CIE 1976 L* a* b* Uniform Color Spa
46、ce andColor-Difference Equation” in Test Method D2244, using theaverage of the replicate measurements, and record them in apermanent record.6.2.4 Measured specimen color values shall be reported tono more than two decimal places, in accordance with therounding method in Practice E29.6.3 Initial Colo
47、r Measurement:6.3.1 Solid colorsAt each weathering location, measurethe color of each file specimen in accordance with 6.2 andrecord the L*a*b* values in a permanent record. The initialL*a*b* values determined from the file specimens are used asthe reference point for all measurements of color chang
48、e of theweathered samples during the duration of the weathering study.6.3.2 Variegated ColorsAt each weathering location,measure the color of each of the six spots on each of the testspecimens in accordance with 6.2. Determine the average ofthe six spots for each test specimen and record the average
49、L*a*b* values in a permanent record. The measured averagecolor of each test specimen is the specimens initial color andis used to determine color change after specified periods ofexposure testing.6.4 Exposure:6.4.1 Expose the test specimens at the test sites in specifiedin 6.1.1. Record the test start date in a permanent record.6.4.2 Expose the specimens at an angle of 45 facing Southand backed using unpainted plywood in accordance to Prac-tices D1435 and G147. The surface of the specimens must befully exposed.6.4.3 Remove test specimens for color measurement
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