1、Designation: D4141/D4141M 14Standard Practice forConducting Black Box and Solar Concentrating Exposuresof Coatings1This standard is issued under the fixed designation D4141/D4141M; the number immediately following the designation indicates theyear of original adoption or, in the case of revision, th
2、e year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This practice covers two accelerated outdoor exposureprocedures for evaluating the exterior weather resista
3、nce ofcoatings applied to substrates.1.2 The two procedures are as follows:1.2.1 Procedure ABlack Box Exposure.1.2.2 Procedure CFresnel Reflector Rack Exposure.NOTE 1Procedure B described a Heated Black Box procedure that isno longer in common use.1.3 This standard does not cover all the procedures
4、that areavailable to the user for accelerating the outdoor exposure ofcoatings. Other procedures have been used in order to providea particular effect; however, the two procedures described hereare widely used.1.4 The values stated in either SI units or inch-pound unitsare to be regarded separately
5、as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.5 This standard does not purport to address all of thesafety concerns, if a
6、ny, 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.2. Referenced Documents2.1 ASTM Standards:2D523 Test Method for Specular GlossD660 Test Meth
7、od for Evaluating Degree 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
8、(Scal-ing) of Exterior PaintsD823 Practices for Producing Films of Uniform Thicknessof Paint, Varnish, and Related Products on Test PanelsD2244 Practice for Calculation of Color Tolerances andColor Differences from Instrumentally Measured ColorCoordinatesD4214 Test Methods for Evaluating the Degree
9、of Chalkingof Exterior Paint FilmsD7091 Practice for Nondestructive Measurement of DryFilm Thickness of Nonmagnetic Coatings Applied toFerrous Metals and Nonmagnetic, Nonconductive Coat-ings Applied to Non-Ferrous MetalsG7 Practice for Atmospheric Environmental Exposure Test-ing of Nonmetallic Mater
10、ialsG90 Practice for Performing Accelerated Outdoor Weather-ing of Nonmetallic Materials Using Concentrated NaturalSunlightG113 Terminology Relating to Natural and Artificial Weath-ering Tests of Nonmetallic MaterialsG141 Guide for Addressing Variability in Exposure Testingof Nonmetallic MaterialsG1
11、47 Practice for Conditioning and Handling of Nonmetal-lic Materials for Natural and Artificial Weathering TestsG169 Guide for Application of Basic Statistical Methods toWeathering Tests3. Terminology3.1 The definitions given in Terminology G113 are appli-cable to this practice.4. Summary of Practice
12、4.1 Several procedures are described that provide accelera-tion of the degradation that coatings evidence during naturalweathering when exposed on an open rack at a fixed angle. Theprocedures appear in the following order:1This practice is under the jurisdiction of ASTM Committee D01 on Paint andRel
13、ated Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.27 on Accelerated Testing.Current edition approved Feb. 1, 2014. Published February 2014. Originallyapproved in 1982. Last previous edition approved in 2007 as D4141 07. DOI:10.1520/D4141/D4141M-14.2For re
14、ferenced 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 standardCop
15、yright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.1.1 Procedure AExposure on a black box rack facing theequator at 5 from the horizontal.4.1.2 Procedure CExposure on a Fresnel reflector rackthat provides a high irradiance by following th
16、e sun andconcentrating sunlight on the test specimens by means ofmirrors. The specimens are wet periodically by high puritywater spray.4.2 The selection of Procedure A or C is dependent onseveral factors.4.2.1 Procedure A is designed to simulate the weatheringthat occurs on horizontal insulated surf
17、aces. Specimens aretypically flat-coated metal panels measuring 10 by 30 cm 4 by12 in. or 15 by 30 cm 6 by 12 in.NOTE 2Procedure A is specified in standards used by the automotiveindustry.4.2.2 Procedure C is designed to simulate weathering onboth automotive and nonautomotive products. Procedure Cty
18、pically provides faster results than Procedure A on a calendarbasis.35. Significance and Use5.1 As with any accelerated test, the increase in rate ofweathering compared to in service exposure is material depen-dent. Therefore, no single acceleration factor can be used torelate two different types of
19、 outdoor weathering exposures. Theweather resistance rankings of coatings provided by these twoprocedures may not agree when coatings differing in compo-sition are compared. These two procedures should not be usedinterchangeably.5.2 The procedures described in this practice are designed toprovide gr
20、eater degradation rates of coatings than those pro-vided by fixed angle open-rack outdoor exposure racks. Formany products, fixed angle exposures will produce higherdegradation rates than the normal end use of the material.5.2.1 The use of Procedure A (Black Box) instead of anopen-rack direct exposu
21、re is a more realistic test for materialswith higher temperature end use service conditions. For manycoatings, this procedure provides greater rates of degradationthan those provided by 5, equator-facing, open-rack exposuresbecause the black box produces higher specimen temperaturesduring irradiatio
22、n by daylight and longer time of wetness. Theblack box specimen temperatures are comparable to thoseencountered on the hoods, roofs, and deck lids of automobilesparked in sunlight. The relative rates of gloss loss and colorchange produced in some automotive coatings by exposures inaccordance with Pr
23、ocedure A are given in ASTM STP 781.45.2.2 The acceleration of Procedure C is produced byreflecting sunlight from ten mirrors onto an air-cooled speci-men area. In the ultraviolet portion of the solar spectrum,approximately 1400 MJ/m2of ultraviolet radiant exposure (295to 385 nm) is received over a
24、typical one-year period whenthese devices are operated in a central Arizona climate. Thiscompares with approximately 333 MJ/m2of ultraviolet radiantexposure from a central Arizona at-latitude exposure and 280MJ/m2of ultraviolet radiant exposure from a southern Floridaat-latitude exposure over the sa
25、me time period. However, thetest described by Procedure C reflects only direct beamradiation onto test specimens. The reflected direct beam ofsunlight contains a lower percentage of short wavelengthultraviolet radiation than global daylight because short wave-length ultraviolet is more easily scatte
26、red by the atmosphere,and because mirrors are typically less efficient at shorterultraviolet wavelengths. Ultraviolet radiant exposure levelsshould not be used to compute acceleration factors sinceacceleration is material dependent.5.3 The weather resistance of coatings in outdoor use can bevery dif
27、ferent depending on the geographic location of theexposure because of differences in ultraviolet (UV) radiation,time of wetness, temperature, pollutants, and other factors.Therefore, it cannot be assumed that results from one exposurein a single location will be useful for determining relativeweathe
28、r resistance in a different location. Exposures in severallocations with different climates that represent a broad range ofanticipated service conditions are recommended.5.4 Because of year-to-year climatological variations, re-sults from a single exposure test cannot be used to predict theabsolute
29、rate at which a material degrades.NOTE 3Several years of repeat exposures are typically needed to getan “average” test result for a given location.5.4.1 The degradation profile for many polymers is not alinear function of exposure time or radiant exposure. Whenshort exposures are used as indications
30、 of weather resistance,the results obtained may not be representative of those fromlonger exposures.NOTE 4Guide G141 provides information for addressing variability inexposure testing of nonmetallic materials. Guide G169 provides informa-tion for applying statistics to exposure test results.5.5 It i
31、s recommended that at least one control material bepart of any exposure evaluation. Control materials are used forcomparing the performance of the test materials relative to thecontrols when materials are not being ranked against oneanother. The control material used should be of similarcomposition
32、and construction to the test materials and be ofknown weather resistance. It is preferable to use two controlmaterials, one with relatively good weather resistance and onewith poor weather resistance.6. Test Specimens6.1 Each test specimen and control specimen shall consist ofa uniform coating appli
33、ed to the surface of a flat panel becausewarpage, waviness, or curvature may seriously affect themeasurement of gloss and color. Flat, rigid specimens arepreferred. Non-rigid specimens shall be backed to ensure aproper seal on the black box rack (Procedure A), or to ensureproper cooling (Procedure C
34、). Suitable application proceduresare given in Practices D823.6.2 For Procedure C, specimen sizes are typically limited toa maximum of 13 cm 5 in. in one dimension, and a maximumof 140 cm 55 in. in the other dimension. However, specimens3Zerlaut, G.A., Rupp, M.W., and Anderson, T.E., “Ultraviolet Ra
35、diation as aTiming Technique for Outdoor Weathering of Materials,” Paper 850378,Proceedings, SAE International Congress, Detroit, February 25, 1985.4Symposium on Permanence of Organic Coatings, ASTM STP 781, ASTM,1982.D4141/D4141M 142are typically 7.5 by 13 cm 3 by 5 in. or 5 by 13 cm 2 by 5in. Beca
36、use air cooling is used to prevent high specimentemperatures, specimens must be flat. A thickness of less than0.6 cm 0.25 in. is preferred. This practice may not apply tospecimens thicker than 1.3 cm 0.5 in. because cooling may bequestionable.6.3 It is recommended that controls be prepared for inclu
37、-sion in each exposure series to act as comparison standards andto provide a means for determining the severity of the exposureconditions encountered by the series. For best results, thereshould be at least two controls differing in their weatherresistance performance.6.4 It is recommended that the
38、dry film thickness of thecoatings be measured at several different positions on the testspecimens in accordance with Test Method D7091.6.5 Unless otherwise specified, expose at least two repli-cates. Larger numbers of replicates are recommended.PROCEDURE ABLACK BOX EXPOSURE7. Apparatus7.1 Black Box,
39、 constructed of materials in accordance withPractice G7, or its equivalent, and positioned so that thesurfaces of the test specimens are 5 from the horizontal, facingthe equator (Figs. 1 and 2).8. Procedure8.1 Use Practice G147 for specimen handling and condi-tioning procedures for test specimens.8.
40、2 If a change in gloss is to be measured, determine thespecular gloss value for each unexposed specimen using aproperly calibrated glossmeter in accordance with Test MethodD523.8.3 If a change in color is to be measured, determine thedelta (change in) color coordinates for each unexposed speci-men u
41、sing Practice D2244. Unless otherwise agreed upon, usethe CIE (1976) L*a*b* (CIE Lab) Color Scale, illuminant D65,and the 1964 10 Observer with specular reflection included.The color measuring instrument shall be stable and properlycalibrated.NOTE 5As an alternative procedure, reserve unexposed dupl
42、icatespecimen panels of each coating as file specimens to determine the colorchange of the exposed specimens. To minimize color drift, store the panelsin a dark, room-temperature environment.8.4 Mount and fasten the specimens on the exposure box.Cover all empty spaces on the black box using black pa
43、nels sothat the entire surface is covered.NOTE 6The predominant color of the specimens on the black boxshould be noted. For example, a black box will attain a lower temperatureif all the specimens are white than if some specimens are black.8.4.1 Non-rigid specimens shall be backed to keep speci-mens
44、 from sagging and to ensure that there are no gapsbetween specimens. The backing material used can be eitherflattened-mesh expanded metal sheet or solid sheet made froma corrosion-resistant material such as aluminum or stainlesssteel. If specimens are backed, the backing material used shallbe specif
45、ied in the report.8.5 Expose the test and control specimens for a specifiedperiod of time on the basis of one of the following:8.5.1 Expose for a specified number of days, months, oryears with respect to an agreed upon starting date.8.5.2 Expose for a specified quantity of radiant exposureeither tot
46、al, typically measured from 300 to 3000 nm, orultraviolet, typically measured from 295 to 385 nm. Whensolar ultraviolet radiation is measured, use a total ultravioletradiometer that measures ultraviolet in the wavelength regionfrom 295 to 385 nm. Optionally, ultraviolet can be measured inthe wavelen
47、gth region from 300 to 400 nm. Calibrate theradiometer and readout system in suitable radiometric units,and maintain in at least annual calibration against a standardsource of spectral irradiance.8.5.3 Expose until a specified change has occurred in thetest specimens.8.5.4 Expose until a specified c
48、hange has occurred in acontrol exposed with the test specimens.8.5.5 In most cases, periodic evaluation of test and controlmaterials is necessary to determine the variation in magnitudeand direction of property change as a function of time orradiant exposure.8.6 Unless otherwise agreed upon, remove
49、the test speci-mens from the black box and gently wash a portion of thespecimen surfaces to remove loose dirt. The same portion ofthe specimen should be washed at each interval of exposure. Asuitable procedure consists of gentle rubbing with a sponge wetwith high purity water or a dilute solution of a nonionicdetergent, followed by a high purity water rinse. The high-purity water shall meet as a minimum the requirements forwater purity contained in Practice G90.8.7 If required, perform one or more of the following testson the washed portion of each w
