1、Designation: E 2539 08Standard Practice forMultiangle Color Measurement of Interference Pigments1This standard is issued under the fixed designation E 2539; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、 A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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“gonioapparent.” The tristimulu
3、s 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 reflectance factor
4、s of the object, the CIE Standard Observer, and the spectral powerdistribution of the illuminant, as described in Practice E 308. This Practice, E 2539, specifies the colormeasurement of interference pigments at various illumination and detection angles.1. Scope1.1 This practice covers the instrumen
5、tal requirements andrequired parameters needed to make instrumental color mea-surements of thin film interference pigments. This practice isdesigned to encompass interference pigments used in architec-tural applications, automobiles, coatings, cosmetics, inks,packaging, paints, plastics, printing, s
6、ecurity, and other appli-cations.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 practice are quantitative and areappropriate for quality control of interfer
7、ence pigment color.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-interference pigments.The comm
8、ittee is investigating and evaluating the appropriate-ness of this practice for those materials. It is the responsibilityof the users to determine the applicability of this practice fortheir specific applications.1.6 Interference pigments are typically evaluated for colorand color appearance in a me
9、dium, 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,for quality control purposes,
10、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 to final product applicatio
11、n.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 Practice E 2194.1.8 The values stated in SI units are to be regarded as thestan
12、dard. 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 practices and determine the applica
13、-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E 284 Terminology of AppearanceE 308 Practice for Computing the Colors of Objects byUsing the CIE SystemE 805 Practice for Identification of Instrumental Methods ofColor or Color-Difference Measurement of Mater
14、ialsE 1164 Practice for Obtaining Spectrometric Data forObject-Color EvaluationE 1345 Practice for Reducing the Effect of Variability ofColor Measurement by Use of Multiple Measurements1This practice is under the jurisdiction of ASTM Committee E12 on Color andAppearance and is the direct responsibil
15、ity of Subcommittee E12.12 on Gonioap-parent Color.Current edition approved Feb. 1, 2008. Published February 2008.2For 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 th
16、e standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.E 1708 Practice for Electronic Interchange of Color andAppearance DataE 1767 Practice for Specifying the Geometries of Observa-tion
17、and Measurement to Characterize the Appearance ofMaterialsE 2194 Practice for Multiangle Color Measurement ofMetal Flake Pigmented MaterialsE 2480 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method with Multi-Valued Measurands2.2 ISCC Publications:3Technical
18、Report 20031 Guide to Material Standards andTheir Use in Color Measurement3. Terminology3.1 Terms and definitions in Terminology E 284, and Prac-tices E 1767 and E 2194 are applicable to this practice. SeeSection 5 of E 284 for “Specialized Terminology on Gonioap-parent Phenomena.”4. Summary of Prac
19、tice4.1 This practice describes the instrumental geometries,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
20、 anddetection angles are specified in the practice. Standardizationand 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 tristim
21、ulusvalues, and other color coordinate systems that define the colorof the object. Expected values of precision are presented.5. Significance and Use5.1 This practice is designed to provide color data obtainedfrom spectral reflectance factors at specific illumination anddetection angles for interfer
22、ence pigments. Information pre-sented in this test practice is based upon data taken on materialsexclusively 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 statisticall
23、y representative of the enduse.5.4 Applicability of this practice for other materials, includ-ing combining interference pigments with absorbing and scat-tering pigments should be confirmed by the user.6. Environmental Conditions6.1 If the standard laboratory conditions listed belowchange during the
24、 test or from test to test by an appreciableamount, 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.
25、2.1 Extraneous radiationlight from sources other thanthe 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 T
26、hermal changestemperature changes occurringduring a 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 m
27、ust allow for successfulstandardization. If the system 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 fo
28、r these factors are typically determined experimentallyby the user.7. Apparatus7.1 Multi-angle SpectrometerThis practice specifies therequired illumination and detection angles of multiangle spec-trometers. These multiangle spectrometers are designed spe-cifically to characterize the optical behavio
29、r of materialscolored with interference pigments. 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 usin
30、g hemispherical geometry cannot ad-equately characterize the gonioapparency of these materials.7.1.2 Multi-angle spectrometers or colorimeters similar tothose specified in Practice E 2194 cannot adequately charac-terize the gonioapparency of these materials.7.2 System Validation MaterialsThe precisi
31、on and bias ofthe entire measurement system, including calculation of CIEtristimulus 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 The ang
32、les 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 illumination ano
33、rmal angle,detection anormal angle, and detection aspecular angle en-closed in parenthesis. See Practice E 1767. For the example ofan illumination angle of 45 and a detection angle of -303Available from the Inter-Society Color Council, 1191 Sunset Hills Road,Reston, VA 20190, www.iscc.org.4ISCC Tech
34、nical Report 20031.E2539082(implying an aspecular angle of 15), the geometry should bedesignated as 45:-30 (as 15).NOTE 1For either illumination 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
35、understood to be thesmaller of the two supplementary angles defined by the ray and thenormal. In a uniplanar geometry, a rays anormal 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
36、 awayfrom the specular direction, in the illumination plane. Positive values ofthe aspecular angle are in the direction toward the illumination axis.8.2.3 For the reflectance-factor measurements of interfer-ence pigments, the instruments illumination and detectionangles shall conform to the angles a
37、s specified in Table 1.These angles are required to measure the range of colorsexhibited by interference pigments.8.2.4 For the reflectance-factor measurement of materialspigmented with metal-flake pigments and interference pig-ments, additional information is provided by angles specifiedin Table 2.
38、 These angles are used to measure the color traveldue to pigment flake-orientation effects and light scatteringfrom the flake edges.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 test
39、ed and should meet the require-ments listed below. If the specimens do not meet theserequirements, include this information in the 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 s
40、urface or stackspecimens without a protective medium between them asrecommended by the provider.9.3 Specimen CleaningIf necessary, clean the specimensfollowing the providers recommended cleaning procedure.9.4 Specimen ConditioningAllow specimens to stabilizein the measurement environment for a time
41、period agreed to bythe parties concerned.9.5 Specimen Physical Requirements :9.5.1 For test specimens that will be assessed visually, 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
42、.NOTE 3This recommendation for specimen size corresponds to thephysical size required for observation by the CIE 1964 Standard Observer(10). The specimen must subtend at least 10 when being observed.Observation usually occurs at approximately 45 cm (17.7 in) from the eye.9.5.2 The surface of the spe
43、cimen should be planar.9.6 Specimen Optical Requirements:9.6.1 UniformityReference and test specimens should beuniform in color and appearance. For materials pigmented withinterference or metallic pigments, measurements on differentlocations on the sample are necessary to assess the degree ofnon-uni
44、formity. These data are also useful for determining thenumber of measurements necessary to achieve a value that isstatistically representative of the sample. See Practice E 1345.Additionally, the samples-must be similar in appearance tomake meaningful observations. There should be no appearanceof mo
45、ttling or banding in the specimens.9.6.2 GlossSpecimens should be uniform and similar ingloss when viewed in a lighting booth.9.6.3 Surface TextureThe specimens being comparedshould have substantially similar surface textures. Orange peelis a common example of surface texture.9.6.4 OrientationConsis
46、tent orientation of the specimenfor presentation to the measuring instrument must be controlledfor repeatable measurements. This is necessary to minimizeerrors due to indiscriminate matching of the directionality ofthe specimen to that of the instrument.10. Instrument Standardization10.1 Standardiza
47、tion is necessary to adjust the instrumentsoutput to correspond to a previously established calibrationusing one or more homogeneous specimens or referencematerials. For the measurement of reflectance factor, full scaleand zero standardization are necessary. See Practice E 1164.10.2 Full-Scale Stand
48、ardization PlaqueA standardizationplaque with assigned spectral reflectance factors relative to theperfect reflecting diffuser, traceable to a national standardizinglaboratory, for each illumination and detection angle is re-quired to standardize the instrument. The instrument manufac-turer typicall
49、y supplies and assigns the standardization valuesto this plaque.NOTE 4Different instrumentation manufacturers use different interna-tional standardization laboratories, different calibration techniques, anddifferent standard reference materials. These factors and others mayinfluence the numerical values obtained from subsequent measurementsand thus care must be exercised when comparing values obtained fromdifferent instruments.TABLE 1 Specified Geometries for Measuring the Color Rangedue to InterferenceIlluminationAngleDetectionAngleAspecularAngl
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