1、Designation: D7856 14D7856 15Standard 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 oforigina
2、l 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 Scope*1.1 This specification establishes requirements and test method
3、s for the color and appearance retention of solid and variegatedcolored plastic siding products.1.2 Color retention testing provides a method for estimating the acceptability of color change in a siding product over a periodof years of service. The exposure locations and durations specified in this
4、standard have been shown to provide a good estimationof the color change in a siding product over a period of years of service (see 2.2).1.3 This specification is a successor to Specifications D6864 and D7251, which cover solid colors and variegated colors,respectively. This specification combines c
5、overage for both, and has the same scope as those standards.1.4 Specifications D6864 and D7251 use Hunter Lab color space for measurement of colors and evaluation of color change.These standards require classification of colors into regions based on the L, a, and b coordinates of the color, and eval
6、uation ofcolor changes is done using an ellipsoid value equation having unique coefficients for each color region. This specification usesCIE 1976 L* a* b* color space for measurement and evaluation of color change. Using this method, the need for separate colorregions and evaluation equations has b
7、een eliminated.1.5 Provisions for sample selection and preparation, and weathering are the same in this specification as in Specifications D6864and D7251.1.6 Characterization of color and appearance for variegated colors is complicated by the presence of multiple colors in a randompattern. The proce
8、dure for measuring variegated colors in this specification is based on using a template to reference six spots forcolor measurement.1.7 This standard specifies outdoor weathering in three specific climate zones for a single 24-month exposure, and the colorretention performance requirements under the
9、se conditions are established to predict acceptable performance for the expectedservice life. However, nothing in this standard precludes the use of different or additional climate zones, or different exposuredurations, so long as those conditions are clearly specified in any reports.1.8 UnitsThe va
10、lues stated in inch-pound units are to be regarded as standard. The values given in parentheses aremathematical conversions to SI units that are provided for information only and are not considered standard.1.9 This standard does not purport to address all of the safety concerns, if any, associated
11、with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.NOTE 1There is no known ISO equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:2D660 Test M
12、ethod for Evaluating Degree of Checking of Exterior PaintsD661 Test Method for Evaluating Degree of Cracking of Exterior PaintsD662 Test Method for Evaluating Degree of Erosion of Exterior PaintsD714 Test Method for Evaluating Degree of Blistering of Paints1 This test method is under the jurisdictio
13、n of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.24 on Plastic Building Products.Current edition approved Feb. 1, 2014April 1, 2015. Published February 2014April 2015. DOI: 10.1520/D7856-14.Originally approved in 2014. Last previous editionapproved in 2014 as
14、D7856 14. DOI:10.1520/D7856-15.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM s
15、tandard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all c
16、ases only the current versionof the standard as published by ASTM is to be considered the official document.*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 States1D772 Test Met
17、hod for Evaluating Degree of Flaking (Scaling) of Exterior PaintsD883 Terminology Relating to PlasticsD1435 Practice for Outdoor Weathering of PlasticsD1600 Terminology for Abbreviated Terms Relating to PlasticsD2244 Practice for Calculation of Color Tolerances and Color Differences from Instrumenta
18、lly Measured Color CoordinatesD4214 Test Methods for Evaluating the Degree of Chalking of Exterior Paint FilmsD6864 Specification for Color and Appearance Retention of Solid Colored Plastic Siding ProductsD7251 Specification for Color and Appearance Retention of Variegated Color Plastic Siding Produ
19、ctsE29 Practice for Using Significant Digits in Test Data to Determine Conformance with SpecificationsE805E1331 Practice for Identification of Instrumental Methods of Color or Color-Difference Measurement of MaterialsTestMethod for Reflectance Factor and Color by Spectrophotometry Using Hemispherica
20、l GeometryG147 Practice for Conditioning and Handling of Nonmetallic Materials for Natural and Artificial Weathering Tests2.2 Other Reference:VS2W Vinyl Siding Institute (VSI) Technical Research Report for Weatherability of Vinyl Siding Products3NOTE 2The report cited in 2.2 supports the conclusion
21、that commercial vinyl siding products which demonstrate weathering behavior withinconformance to these standards during a two year test program can be anticipated to provide acceptable color retention properties for the expected lifeof the product.3. Terminology3.1 DefinitionsDefinitions are in acco
22、rdance with Terminologies D883 and D1600 unless otherwise noted.3.2 Definitions of Terms Specific to This Standard:3.2.1 temperate northern climatein weathering testing, a North American metropolitan area testing site within 73 to 100Wlongitude and 37 to 45N latitude.3.2.2 variegated plastic sidings
23、iding having discrete markings of different colors.4. Sampling and Specimen Preparation4.1 Samples shall be representative of the product to be evaluated. Samples shall be taken either from commercial products orfrom laboratory samples. Laboratory samples shall be produced in the same manner as the
24、commercial products to be evaluated.NOTE 3Production of laboratory samples in the same manner includes use of the same method of forming the product. For example, if the commercialproduct is extruded, the laboratory specimen shall be extruded; if the commercial product is injection molded, the labor
25、atory specimen shall be injectionmolded, and so forth.4.2 Mark each specimen permanently to ensure retention of identity during and after exposure testing. Ensure that theidentification marking is small and does not interfere with the color measuring area.NOTE 4Use of a vibratool leaves a permanent
26、mark that satisfies this criterion.4.3 Solid Color Specimens:4.3.1 Prepare a minimum of four specimens per sample per test site to allow for three test specimens and one file specimen foreach sample evaluated.4.3.2 The file specimen will be measured for color at each test location and will serve as
27、the reference color for evaluation ofcolor changes in the three replicates after weathering.4.3.3 Specimens shall be a flat section and a minimum of 2 by 334 in. (51 by 95 mm). If the normally-exposed surface of thesiding is heavily textured to the extent that correct or consistent color measurement
28、s cannot be obtained, weathering test exposureof the back surface or other surface is permitted, so long as the surface is representative of the exposed surface.4.4 Variegated Color Specimens:4.4.1 Prepare a minimum of four specimens per sample per test site to allow for three test specimens and one
29、 file specimen foreach sample evaluated.4.4.2 The file specimen will be used for a visual assessment of variegation/contrast change.The test specimens will be measuredfor color and weathered.4.4.3 Specimens shall be a flat section and a minimum of 3 by 10 in. (76 by 254 mm). The variegated pattern s
30、hall be parallelto the long edge of the specimen.4.4.4 Use the Variegated Color Measurement Template to identify the six spots on each test specimen for color retention testing.The center points of these six spots are specified in Fig. 1.The diameter of the six spots is specified as 0.50 in. (12.2 m
31、m) minimum.The actual diameter used shall be large enough to admit the aperture plate of the instrument used without extraneous light leakage.4.4.5 The exact locations of these test spots must be determined and recorded for each test specimen to allow measurement ofcolor change following exposure te
32、sting. The locations and spot sizes identified in 4.4.4 for each test specimen shall not changeonce the exposure test is started.3 Available from Vinyl Siding Institute (VSI), National Housing Center, 1201 15th Street NW, Suite 220, Washington, DC 20005, http:/www.vinylsiding.org.D7856 1525. Procedu
33、re5.1 Outdoor Weathering:5.1.1 Samples shall be exposed at three test sites: Temperate Northern represented by a site located in near Louisville, KY orCleveland, OH; hot, humid represented by a site located near Miami, FL; and hot, dry represented by a site located near Phoenix,AZ. Actual test locat
34、ions are not limited to these representative cities so long as the location is representative of the indicatedclimate zone.5.2 Color Measurement (General):5.2.1 All color measurements are to be made in accordance with this section. Obtain test and file specimens in accordance with4.3 or 4.4. The fol
35、lowing procedure is used at each of the three weathering locations.5.2.2 Color is measured using 8 sphere geometry, diffuse illumination, specular component included (di:8), Illuminant D65,and 10 observer, in accordance with Practice Test Method E805E1331. For solid colors make at least three separa
36、te measurementson the specimen and average them. For variegated colors take one reading 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 accordance with the “CIE 1976 L* a* b* Uniform Color Space andColor-Difference Equation” in Test Method D
37、2244, using the average of the replicate measurements, and record them in apermanent record.FIG. 1 Variegated Color Measurement TemplateD7856 1535.2.4 Measured specimen color values shall be reported to no more than two decimal places, in accordance with the roundingmethod in Practice E29.5.3 Initia
38、l Color Measurement:5.3.1 Solid colorsAt each weathering location, measure the color of each file specimen in accordance with 5.2 and record theL*a*b* values in a permanent record. The initial L*a*b* values determined from the file specimens are used as the reference pointfor all measurements of col
39、or change of the weathered 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 test specimensin accordance with 5.2. Determine the average of the six spots for each test specimen and record
40、the average L*a*b* values ina permanent record. The measured average color of each test specimen is the specimens initial color and is used to determine colorchange after specified periods of exposure testing.5.4 Exposure:5.4.1 Expose the test specimens at the test sites in specified in 5.1.1. Recor
41、d the test start date in a permanent record.5.4.2 Expose the specimens at an angle of 45 facing South and backed using unpainted plywood in accordance to PracticesD1435 and G147. The surface of the specimens must be fully exposed.5.4.3 Remove test specimens for color measurement after 24 months of e
42、xposure.5.4.4 If the specimens are to be subjected to further weathering exposure, return them to the test rack no later than seven daysafter removal.5.5 Color Measurement and Appearance Evaluation:5.5.1 After they are removed from exposure, wash the exposed test specimens in accordance with the pro
43、cedure in Annex A1.5.5.2 Measure the exposed test specimens for color and evaluate them for appearance and surface condition. Color measurementshall take place within seven days of specimen removal from the exposure test rack. Record the date and time of removal and thedate and time of color measure
44、ment.NOTE 5It is recommended that color measurement and appearance evaluation be conducted at the test site. Additional color development is knownto occur for PVC products after removal from exposure to solar radiation. This artificial color change is referred to as Dark Time Yellowing. It isrecomme
45、nded that color measurement take place within 48 h of the specimens removal from the exposure test rack, especially for PVC products.5.5.3 Solid ColorsMeasure the color of each test specimen in accordance with 5.2 and record the L*a*b* values in apermanent record.5.5.4 Variegated ColorsReferencing t
46、he file specimen, evaluate each test specimen for loss of variegation in accordance with6.6. Measure the color of each of the six spots on each of the test specimens in accordance with 5.2. Determine the average of thesix spots for each test specimen and record average L*a*b* values in a permanent r
47、ecord.5.5.5 Visual EvaluationFor both solid and variegated colors, evaluate each test specimen for appearance and surface conditionin accordance with Annex A2.6. Performance Requirements6.1 For each specimen determine the change in L*, a*, and b* between the initial color measurement and the color m
48、easurementafter 24 months exposure. For solid colors the initial color reference is to the file specimen, determined in 5.3.1. For variegatedcolors the initial color reference is to the initial color of that test specimen, determined in 5.3.2.6.2 The E00 for an individual specimen is calculated usin
49、g the measured color change and the “CIEDE2000 Color DifferenceEquation” in Test Method D2244. For KL, KC, KH, use a value of 1. Average the E00 for the three test specimens of each colorat each test location.6.3 Acceptable color retention is determined by the average E00 of the three test specimens at each test location being less thanor equal to 4.0. In addition, no individual specimen shall have a E00 greater than 6.0. For purposes of determining compliancewith these requirements, the calculated value of E00 shall be rounded to the nearest one deci
