1、Designation: E2539 14 (Reapproved 2017)Standard Test Method forMultiangle Color Measurement of Interference Pigments1This standard is issued under the fixed designation E2539; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the yea
2、r 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.INTRODUCTIONObjects that exhibit a change in color with different angles of illumination and view are said to be“gonioapparen
3、t.” The tristimulus colorimetric values of gonioapparent objects are derived using thespectral reflectance factors obtained from spectrometric measurements or colorimetric measurementsat various angles of illumination and detection.The tristimulus colorimetric values are computed usingthe spectral r
4、eflectance factors of the object, the CIE Standard Observer, and the spectral powerdistribution of the illuminant, as described in Practice E308. This Test Method, E2539, specifies thecolor measurement of interference pigments at various illumination and detection angles.1. Scope1.1 This test method
5、 covers the instrumental requirementsand required parameters needed to make instrumental colormeasurements of thin film interference pigments. This testmethod is designed to encompass interference pigments used inarchitectural applications, automobiles, coatings, cosmetics,inks, packaging, paints, p
6、lastics, printing, security, and otherapplications.1.2 Characterization of the optical behavior of materialscolored with interference pigments requires measurement atmultiple angles of illumination and detection.1.3 Data taken utilizing this test method are quantitative andare appropriate for qualit
7、y control of interference pigmentcolor.1.4 The measurement results are usually expressed as re-flectance factors, tristimulus color values, or as CIE L*a*b*color coordinates and color difference.1.5 The totality of data taken may not be necessary forevaluating mixtures also containing non-interferen
8、ce pigments.The committee is investigating and evaluating the appropriate-ness of this test method for those materials. It is the responsi-bility of the users to determine the applicability of this testmethod for their specific applications.1.6 Interference pigments are typically evaluated for color
9、and color appearance in a medium, such as paint or ink. Thegonioapparent effect depends strongly on the physical andchemical properties of the medium. Some of the propertiesaffecting color and color appearance include vehicle viscosity,thickness, transparency, and volume solids. As a general rule,fo
10、r quality control purposes, interference pigments are bestevaluated in a masstone product form. In some cases thisproduct form may be the final product form, or more typicallya qualified simulation of the intended product form (such as apaint drawdown) that in terms of color and appearancecorrelates
11、 to final product application.1.7 This standard does not address the requirements forcharacterizing materials containing metal flake pigments. Mea-surements of the optical characteristics of materials containingmetal flake pigments are described in Test Method E2194.1.8 The values stated in SI units
12、 are to be regarded as thestandard. The values given in parentheses are for informationonly.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 of this standard to establish appro-priate safety and health pract
13、ices and determine the applica-bility of regulatory limitations prior to use.1.10 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides an
14、d Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.1This test method is under the jurisdiction of ASTM Committee E12 on Colorand Appearance and is the direct responsibility of Subcommittee E12.12 onGonioapparent Color.Current edition approved June 1,
15、 2017. Published June 2017. Originallyapproved in 2008. Last previous edition approved in 2014 as E2539 14. DOI:10.1520/E2539-14R17.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance
16、 with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.12. Referenced Documents2.1 ASTM Stand
17、ards:2E284 Terminology of AppearanceE308 Practice for Computing the Colors of Objects by Usingthe CIE SystemE805 Practice for Identification of Instrumental Methods ofColor or Color-Difference Measurement of MaterialsE1164 Practice for Obtaining Spectrometric Data for Object-Color EvaluationE1345 Pr
18、actice for Reducing the Effect of Variability ofColor Measurement by Use of Multiple MeasurementsE1708 Practice for Electronic Interchange of Color andAppearance DataE1767 Practice for Specifying the Geometries of Observa-tion and Measurement to Characterize the Appearance ofMaterialsE2194 Test Meth
19、od for Multiangle Color Measurement ofMetal Flake Pigmented MaterialsE2480 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method with Multi-Valued Measurands2.2 ISCC Publications:3Technical Report 20031 Guide to Material Standards andTheir Use in Color Measureme
20、nt3. Terminology3.1 Terms and definitions in Terminology E284, and Prac-tice E1767 and Test Method E2194 are applicable to this testmethod. See Section 5 of E284 for “Specialized Terminologyon Gonioapparent Phenomena.”4. Summary of Test Method4.1 This test method describes the instrumental geometrie
21、s,including abridged goniospectrometry, used to measure inter-ference pigments. Optical characterization requires color mea-surement at multiple illumination and multiple detection anglesspecified in this procedure. These sets of illumination anddetection angles are specified in the test method. Sta
22、ndardiza-tion and verification of the instrument used to measure thesematerials are defined. The requirements for selection of speci-mens and measurement procedures are provided. The resultsare reported in terms of reflectance factors, CIE tristimulusvalues, and other color coordinate systems that d
23、efine the colorof the object. Expected values of precision are presented.5. Significance and Use5.1 This test method is designed to provide color dataobtained from spectral reflectance factors at specific illumina-tion and detection angles for interference pigments. Informa-tion presented in this te
24、st method is based upon data taken onmaterials exclusively pigmented with interference pigments.5.2 These data can be used for acceptance testing, designpurposes, research, manufacturing control, and quality control.5.3 Specimens must be statistically representative of the enduse.5.4 Applicability o
25、f this test method for other materials,including combining interference pigments with absorbing andscattering pigments should be confirmed by the user.6. Environmental Conditions6.1 If the standard laboratory conditions listed belowchange during the test or from test to test by an appreciableamount,
26、 these conditions may reduce accuracy and precision ofthis test method. In some cases these effects may only beobserved during the performance of the test.6.2 Factors affecting test resultsThe following factors areknown to affect the test results.6.2.1 Extraneous radiationlight from sources other th
27、anthe illuminator(s) and any near-infrared (NIR) must be shieldedfrom entering the test apparatus.6.2.2 Vibrationsmechanical oscillations that cause com-ponents of the apparatus to move relative to one another maycause errors in test results.6.2.3 Thermal changestemperature changes occurringduring a
28、 test or differences in temperature between testinglocations may affect calibration.6.2.4 Power input fluctuationslarge changes in the linefrequency or supply voltage may cause the apparatus to reporterroneous results.6.3 StandardizationThe system must allow for successfulstandardization. If the sys
29、tem cannot be standardized, consultthe manufacturers user guide.6.4 Controlling factorsAccuracy and precision can beenhanced by controlling and regulating each factor within theconstraints of the allowable experimental error. The values andlimits for these factors are typically determined experiment
30、allyby the user.7. Apparatus7.1 Multiangle SpectrometerThis test method specifies therequired illumination and detection angles of multiangle spec-trometers. These multiangle spectrometers are designed spe-cifically to characterize the optical behavior of materialscolored with interference pigments.
31、 Geometries are specified inSection 8. The spectrometer may either be a goniospectrometeror an abridged goniospectrometer.7.1.1 Bi-directional spectrometers or colorimeters with asingle angle of measurement; such as 45:0 or 0:45, andspectrometers using hemispherical geometry cannot ad-equately chara
32、cterize the gonioapparency of these materials.7.1.2 Multiangle spectrometers or colorimeters similar tothose specified in Test Method E2194 cannot adequatelycharacterize the gonioapparency of these materials.7.2 System Validation MaterialsThe precision and bias ofthe entire measurement system, inclu
33、ding calculation of CIE2For 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.3Available from the Inter-Society Colo
34、r Council, 1191 Sunset Hills Road,Reston, VA 20190, www.iscc.org.E2539 14 (2017)2tristimulus values, should be determined by periodic measure-ment of known, calibrated, verification standards. These stan-dards are supplied by instrument manufacturers or obtainedseparately.48. Geometric Conditions8.1
35、 The angles of illumination and detection are critical tomultiangle measurements of materials pigmented with inter-ference pigments.8.2 Recommended Geometries:8.2.1 All geometries cited here are uniplanar.8.2.2 Geometry DesignationThe angles of illuminationand detection will be specified as illumina
36、tion anormal angle,detection anormal angle, and detection aspecular angle en-closed in parenthesis. See Practice E1767. For the example ofan illumination angle of 45 and a detection angle of -30(implying an aspecular angle of 15), the geometry should bedesignated as 45:-30 (as 15).NOTE 1For either i
37、llumination or detection, an anormal angle isdefined as the angle subtended at the point of incidence by a given ray andthe normal to the surface. An anormal angle is understood to be thesmaller of the two supplementary angles defined by the ray and thenormal. In a uniplanar geometry, a rays anormal
38、 angle has a positive signif that ray and the incident ray (illuminant ray) are on the same side of thenormal.NOTE 2The aspecular angle is the detection angle measured awayfrom the specular direction, in the illumination plane. Positive values ofthe aspecular angle are in the direction toward the il
39、lumination axis.8.2.3 For the reflectance-factor measurements of interfer-ence pigments, the instruments illumination and detectionangles shall conform to the angles as specified in Table 1.These angles are required to measure the range of colorsexhibited by interference pigments.8.2.4 For the refle
40、ctance-factor measurement of materialspigmented with metal-flake pigments and interferencepigments, additional information is provided by angles speci-fied in Table 2. These angles are used to measure the colortravel due to pigment flake-orientation effects and light scat-tering from the flake edges
41、.9. Test Specimen(s)9.1 IntroductionMeasured values depend on the quality ofthe test specimens. The specimens must be statistically repre-sentative of the lot being tested and should meet the require-ments listed below. If the specimens do not meet theserequirements, include this information in the
42、report (Section14).9.2 Specimen HandlingHandle the specimens carefully.Touch them by their edges only. Never lay the measurementsurface of the specimen down on another surface or stackspecimens without a protective medium between them asrecommended by the provider.9.3 Specimen CleaningIf necessary,
43、clean the specimensfollowing the providers recommended cleaning procedure.9.4 Specimen ConditioningAllow specimens to stabilizein the measurement environment for a time period agreed to bythe parties concerned.9.5 Specimen Physical Requirements:9.5.1 For test specimens that will be assessed visually
44、, thesize shall be at least 8 by 8 cm (approximately 3 by 3 in.). Thisspecimen size is well suited for both visual assessment andinstrumental measurement. See also 12.2.NOTE 3This recommendation for specimen size corresponds to thephysical size required for observation by the CIE 1964 Standard Obser
45、ver(10). The specimen must subtend at least 10 when being observed.Observation usually occurs at approximately 45 cm (17.7 in.) from theeye.9.5.2 The surface of the specimen should be planar.9.6 Specimen Optical Requirements:9.6.1 UniformityReference and test specimens should beuniform in color and
46、appearance. For materials pigmented withinterference or metallic pigments, measurements on differentlocations on the sample are necessary to assess the degree ofnon-uniformity. These data are also useful for determining thenumber of measurements necessary to achieve a value that isstatistically repr
47、esentative of the sample. See Practice E1345.Additionally, the samples-must be similar in appearance tomake meaningful observations. There should be no appearanceof mottling or banding in the specimens.9.6.2 GlossSpecimens should be uniform and similar ingloss when viewed in a lighting booth.9.6.3 S
48、urface TextureThe specimens being comparedshould have substantially similar surface textures. Orange peelis a common example of surface texture.9.6.4 OrientationConsistent orientation of the specimenfor presentation to the measuring instrument must be controlledfor repeatable measurements. This is n
49、ecessary to minimizeerrors due to indiscriminate matching of the directionality ofthe specimen to that of the instrument.4ISCC Technical Report 20031.TABLE 1 Specified Geometries for Measuring the Color Rangedue to InterferenceIlluminationAngleDetectionAngleAspecularAngleDesignation45 -60 -15 45:-60 (as-15)45 -30 +15 45:-30 (as15)15 -30 -15 15:-30 (as-15)15 0 +15 15:0 (as15)NoteThis table gives the minimum geometries for the quality control applica-tion. For other applications, additional geometries; such as 65:-50 (a
