1、Designation: D7856 14Standard 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 adopti
2、on 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 specification establishes requirements and testmethods for the color
3、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 siding product over aperiod of years of service. The exposure locations and dura-tions specified in this standard have be
4、en shown to provide agood estimation of the color change in a siding product over aperiod of years of service (see 2.2).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,a
5、nd has the same scope as those standards.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 change
6、s is done using an ellipsoid valueequation 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 Pro
7、visions for sample selection and preparation, 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 var
8、iegated colorsin this specification is 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 estab
9、lished to predict acceptable performance for theexpected service life. However, nothing in this standard pre-cludes the use of different or additional climate zones, ordifferent exposure durations, so long as those conditions areclearly specified in any reports.1.8 UnitsThe values stated in inch-pou
10、nd units are to beregarded 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 theres
11、ponsibility 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 standard.2. Referenced Documents2.1 ASTM Standards:2D660 Test Method for Evaluating De
12、gree of Checking ofExterior 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 Exteri
13、or PaintsD883 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 ColorCoordinatesD4214 Test Methods for Evalu
14、ating the Degree of Chalkingof Exterior Paint Films1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.24 on Plastic BuildingProducts.Current edition approved Feb. 1, 2014. Published February 2014. DOI: 10.1520/D7856-14.2F
15、or 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 C70
16、0, West Conshohocken, PA 19428-2959. United States1D6864 Specification for Color and Appearance Retention ofSolid Colored Plastic Siding ProductsD7251 Specification for Color and Appearance Retention ofVariegated Color Plastic Siding ProductsE29 Practice for Using Significant Digits in Test Data toD
17、etermine Conformance with SpecificationsE805 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 Tests2.2 Other Reference:VS2W Vinyl Siding
18、Institute (VSI) Technical Research Re-port for Weatherability of Vinyl Siding Products3NOTE 2The report cited in 2.2 supports the conclusion that commer-cial vinyl siding products which demonstrate weathering behavior withinconformance to these standards during a two year test program can beanticipa
19、ted to provide acceptable color retention properties for theexpected life of the product.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 temperate northern climatein weatheri
20、ng testing, aNorth American metropolitan area testing site within 73 to100W longitude and 37 to 45N latitude.3.2.2 variegated plastic sidingsiding having discretemarkings of different colors.4. Sampling and Specimen Preparation4.1 Samples shall be representative of the product to beevaluated. Sample
21、s shall be taken either from commercialproducts or from laboratory samples. Laboratory samples shallbe produced in the same manner as the commercial products tobe evaluated.NOTE 3Production of laboratory samples in the same manner includesuse of the same method of forming the product. For example, i
22、f thecommercial product is extruded, the laboratory specimen shall be ex-truded; if the commercial product is injection molded, the laboratoryspecimen shall be injection molded, and so forth.4.2 Mark each specimen permanently to ensure retention ofidentity during and after exposure testing. Ensure t
23、hat theidentification marking is small and does not interfere with thecolor measuring area.NOTE 4Use of a vibratool leaves a permanent mark that satisfies thiscriterion.4.3 Solid Color Specimens:4.3.1 Prepare a minimum of four specimens per sample pertest site to allow for three test specimens and o
24、ne file specimenfor each sample evaluated.4.3.2 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.4.3.3 Specimens shall be a flat section and a minimum of 2by 334 in. (51 by
25、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 surface is representative of the exposed surface.4.4 Varieg
26、ated Color Specimens:4.4.1 Prepare a minimum of four specimens per sample pertest site to allow for three test specimens and one file specimenfor each sample evaluated.4.4.2 The file specimen will be used for a visual assessmentof variegation/contrast change. The test specimens will bemeasured for c
27、olor and weathered.4.4.3 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.4.4.4 Use the Variegated Color Measurement Template toidentify the six spots on each test specimen for color retentiontestin
28、g. 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 withoutextraneous light leakage.4.4.5 The exact locations of these
29、 test spots must bedetermined and recorded for each test specimen to allowmeasurement of color change following exposure testing. Thelocations and spot sizes identified in 4.4.4 for each testspecimen shall not change once the exposure test is started.5. Procedure5.1 Outdoor Weathering:5.1.1 Samples
30、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, dry represented by a site located nearPhoenix, AZ. Actual test locations are not limited to theserepresentativ
31、e cities so long as the location is representative ofthe indicated climate zone.5.2 Color Measurement (General):5.2.1 All color measurements are to be made in accordancewith this section. Obtain test and file specimens in accordancewith 4.3 or 4.4. The following procedure is used at each of thethree
32、 weathering locations.5.2.2 Color is measured using 8 sphere geometry, diffuseillumination, specular component included (di:8), IlluminantD65, and 10 observer, in accordance with Practice E805. Forsolid colors make at least three separate measurements on thespecimen and average them. For variegated
33、colors take onereading at each of the six spots identified in 4.4.4, and averagethem.5.2.3 Calculate the CIE 1976 L*a*b* units in accordancewith the “CIE 1976 L* a* b* Uniform Color Space andColor-Difference Equation” in Test Method D2244, using theaverage of the replicate measurements, and record t
34、hem in apermanent record.5.2.4 Measured specimen color values shall be reported tono more than two decimal places, in accordance with therounding method in Practice E29.3Available from Vinyl Siding Institute (VSI), National Housing Center, 120115th Street NW, Suite 220, Washington, DC 20005, http:/w
35、ww.vinylsiding.org.D7856 1425.3 Initial Color Measurement:5.3.1 Solid colorsAt each weathering location, measurethe color of each file specimen in accordance with 5.2 andrecord the L*a*b* values in a permanent record. The initialL*a*b* values determined from the file specimens are used asthe referen
36、ce point for all measurements of color change of theweathered samples during the duration of the weathering study.5.3.2 Variegated ColorsAt each weathering location,measure the color of each of the six spots on each of the testspecimens in accordance with 5.2. Determine the average ofthe six spots f
37、or each test specimen and record the averageL*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.5.4 Exposure:5.4.1 Expose the test specimens at the test sit
38、es in specifiedin 5.1.1. Record the test start date in a permanent record.5.4.2 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.5.4.3 Remove test specimens for color me
39、asurement after24 months of exposure.5.4.4 If the specimens are to be subjected to further weath-ering exposure, return them to the test rack no later than sevendays after removal.5.5 Color Measurement and Appearance Evaluation:5.5.1 After they are removed from exposure, wash theexposed test specime
40、ns in accordance with the procedure inAnnex A1.FIG. 1 Variegated Color Measurement TemplateD7856 1435.5.2 Measure the exposed test specimens for color andevaluate them for appearance and surface condition. Colormeasurement shall take place within seven days of specimenremoval from the exposure test
41、rack. Record the date and timeof removal and the date and time of color measurement.NOTE 5It is recommended that color measurement and appearanceevaluation be conducted at the test site. Additional color development isknown to occur for PVC products after removal from exposure to solarradiation. Thi
42、s artificial color change is referred to as Dark TimeYellowing. It is recommended that color measurement take place within48 h of the specimens removal from the exposure test rack, especially forPVC products.5.5.3 Solid ColorsMeasure the color of each test speci-men in accordance with 5.2 and record
43、 the L*a*b* values in apermanent record.5.5.4 Variegated ColorsReferencing the file specimen,evaluate each test specimen for loss of variegation in accor-dance with 6.6. Measure the color of each of the six spots oneach of the test specimens in accordance with 5.2. Determinethe average of the six sp
44、ots for each test specimen and recordaverage L*a*b* values in a permanent record.5.5.5 Visual EvaluationFor both solid and variegatedcolors, evaluate each test specimen for appearance and surfacecondition in accordance with Annex A2.6. Performance Requirements6.1 For each specimen determine the chan
45、ge in L*, a*, andb* between the initial color measurement and the colormeasurement after 24 months exposure. For solid colors theinitial color reference is to the file specimen, determined in5.3.1. For variegated colors the initial color reference is to theinitial color of that test specimen, determ
46、ined in 5.3.2.6.2 The E00for an individual specimen is calculated usingthe measured color change and the “CIEDE2000 Color Differ-ence Equation” in Test Method D2244. For KL,KC,KH, use avalue of 1. Average the E00for the three test specimens ofeach color at each test location.6.3 Acceptable color ret
47、ention is determined by the averageE00of the three test specimens at each test location being lessthan or equal to 4.0. In addition, no individual specimen shallhave a E00greater than 6.0. For purposes of determiningcompliance with these requirements, the calculated value ofE00shall be rounded to th
48、e nearest one decimal place inaccordance with the rounding method of Practice E29.6.4 For both solid and variegated colors, the specimen shallbe free of any visual surface or structural changes such aspeeling, chipping, cracking, flaking, and pitting when evalu-ated in accordance to Annex A2.6.5 For
49、 solid colors, each specimen shall be of uniformappearance and void of blemishes, streaks, and splotches.6.6 For variegated colors, acceptable variegation change isany remaining presence of variegation. Failure is defined ascomplete loss of variegation and the presence of a uniformcolor.7. Keywords7.1 color retention; plastic siding; polypropylene siding;vinyl siding; weatherabilityANNEXES(Mandatory Information)A1. WASHING WEATHERING SPECIMENSA1.1 ScopeA1.1.1 This procedure describes a practice for washingweathering specimens prior to instrumental color m
