ASTM D523-1989(2008) Standard Test Method for Specular Gloss.pdf

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1、Designation: D 523 89 (Reapproved 2008)Standard Test Method forSpecular Gloss1This standard is issued under the fixed designation D 523; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parenth

2、eses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This test method covers the measurement of the speculargloss of nonmet

3、allic specimens for glossmeter geometries of60, 20, and 85 (1-7).21.2 The values stated in inch-pound units are to be regardedas the standard. The values given in parentheses are forinformation only.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its

4、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:3D 823 Practices for Producing Films of Uniform Thicknessof Paint, Varnish

5、, and Related Products on Test PanelsD 3964 Practice for Selection of Coating Specimens forAppearance MeasurementsD 3980 Practice for Interlaboratory Testing of Paint andRelated Materials4D 4039 Test Method for Reflection Haze of High-GlossSurfacesE97 Test Method for Directional Reflectance Factor,

6、45-Deg 0-Deg, of Opaque Specimens by Broad-Band FilterReflectometry4E 430 Test Methods for Measurement of Gloss of High-Gloss Surfaces by Abridged Goniophotometry43. Terminology3.1 Definitions:3.1.1 relative luminous reflectance factorthe ratio of theluminous flux reflected from a specimen to the lu

7、minous fluxreflected from a standard surface under the same geometricconditions. For the purpose of measuring specular gloss, thestandard surface is polished glass.3.1.2 specular glossthe relative luminous reflectance fac-tor of a specimen in the mirror direction.4. Summary of Test Method4.1 Measure

8、ments are made with 60, 20, or 85 geometry(8, 9). The geometry of angles and apertures is chosen so thatthese procedures may be used as follows:4.1.1 The 60 geometry is used for intercomparing mostspecimens and for determining when the 20 geometry may bemore applicable.4.1.2 The 20 geometry is advan

9、tageous for comparingspecimens having 60 gloss values higher than 70.4.1.3 The 85 geometry is used for comparing specimensfor sheen or near-grazing shininess. It is most frequentlyapplied when specimens have 60 gloss values lower than 10.5. Significance and Use5.1 Gloss is associated with the capaci

10、ty of a surface toreflect more light in some directions than in others. Thedirections associated with mirror (or specular) reflection nor-mally have the highest reflectances. Measurements by this testmethod correlate with visual observations of surface shininessmade at roughly the corresponding angl

11、es.5.1.1 Measured gloss ratings by this test method are ob-tained by comparing the specular reflectance from the speci-men to that from a black glass standard. Since specularreflectance depends also on the surface refractive index of thespecimen, the measured gloss ratings change as the surfacerefra

12、ctive index changes. In obtaining the visual gloss ratings,however, it is customary to compare the specular reflectancesof two specimens having similar surface refractive indices.Since the instrumental ratings are affected more than the visualratings by changes in surface refractive index, non-agree

13、ment1This test method is under the jurisdiction of ASTM Committee E12 on Colorand Appearance and is the direct responsibility of Subcommittee E12.03 onGeometry.Current edition approved Feb. 1, 2008. Published April 2008. Originallyapproved in 1939. Last previous edition approved in 1999 as D 523 89

14、(1999).2The boldface numbers in parentheses refer to the list of references at the end ofthis test method.3For 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 standa

15、rds Document Summary page onthe ASTM website.4Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.between visual and instrumental gloss ratings can occur whenhigh gloss specimen surfaces differing in refractive index arecompare

16、d.5.2 Other visual aspects of surface appearance, such asdistinctness of reflected images, reflection haze, and texture,are frequently involved in the assessment of gloss (1), (6), (7).Test Method E 430 includes techniques for the measurement ofboth distinctness-of-image gloss and reflection haze. T

17、estMethod D 4039 provides an alternative procedure for measur-ing reflection haze.5.3 Little information about the relation of numerical-to-perceptual intervals of specular gloss has been published.However, in many applications the gloss scales of this testmethod have provided discriminations betwee

18、n coated speci-mens that have agreed well with visual discriminations of gloss(10).5.4 When specimens differing widely in perceived gloss orcolor, or both, are compared, nonlinearity may be encounteredin the relationship between visual gloss difference ratings andinstrumental gloss reading differenc

19、es.6. Apparatus6.1 Instrumental ComponentsThe apparatus shall consistof an incandescent light source furnishing an incident beam,means for locating the surface of the specimen, and a receptorlocated to receive the required pyramid of rays reflected by thespecimen. The receptor shall be a photosensit

20、ive device re-sponding to visible radiation.6.2 Geometric ConditionsThe axis of the incident beamshall be at one of the specified angles from the perpendicular tothe specimen surface. The axis of the receptor shall be at themirror reflection of the axis of the incident beam. The axis ofthe incident

21、beam and the axis of the receptor shall be within0.1 of the nominal value indicated by the geometry. With a flatpiece of polished black glass or other front-surface mirror inthe specimen position, an image of the source shall be formedat the center of the receptor field stop (receptor window). Thele

22、ngth of the illuminated area of the specimen shall be not morethan one third of the distance from the center of this area to thereceptor field stop. The dimensions and tolerance of the sourceand receptor shall be as indicated in Table 1. The angulardimensions of the receptor field stop are measured

23、from thereceptor lens in a collimated-beam-type instrument, as illus-trated in Fig. 1, and from the test surface in a converging-beam-type instrument, as illustrated in Fig. 2. See Fig. 1 andFig. 2 for a generalized illustration of the dimensions. Thetolerances are chosen so that errors in the sourc

24、e and receptorapertures do not produce an error of more than one gloss unitat any point on the scale (5).6.2.1 The important geometric dimensions of any specular-gloss measurement are:6.2.1.1 Beam axis angle(s), usually 60, 20, or 85.6.2.1.2 Accepted angular divergences from principal rays(degree of

25、 spreading or diffusion of the reflected beam).NOTE 1The parallel-beam glossmeters possess the better uniformityof principle-ray angle of reflection, but the converging-beam glossmeterspossess the better uniformity in extent of angular divergence accepted formeasurement.NOTE 2PolarizationAn evaluati

26、on of the impact of polarization ongloss measurement has been reported (11). The magnitude of the polar-ization error depends on the difference between the refractive indices ofspecimen and standard, the angle of incidence, and the degree ofpolarization. Because the specimen and standard are general

27、ly quitesimilar optically, measured gloss values are little affected by polarization.6.3 VignettingThere shall be no vignetting of rays that liewithin the field angles specified in Table 1.6.4 Spectral ConditionsResults should not differ signifi-cantly from those obtained with a source-filter photoc

28、ellcombination that is spectrally corrected to yield CIE luminousefficiency with CIE source C. Since specular reflection is, ingeneral, spectrally nonselective, spectral corrections need to beapplied only to highly chromatic, low-gloss specimens uponagreement of users of this test method.6.5 Measure

29、ment MechanismThe receptor-measurementmechanism shall give a numerical indication that is propor-tional to the light flux passing the receptor field stop with61 % of full-scale reading.7. Reference Standards7.1 Primary StandardsHighly polished, plane, black glasswith a refractive index of 1.567 for

30、the sodium D line shall beassigned a specular gloss value of 100 for each geometry. Thegloss value for glass of any other refractive index can becomputed from the Fresnel equation (5). For small differencesin refractive index, however, the gloss value is a linear functionof index, but the rate of ch

31、ange of gloss with index is differentfor each geometry. Each 0.001 increment in refractive indexproduces a change of 0.27, 0.16, and 0.016 in the gloss valueassigned to a polished standard for the 20, 60, and 85geometries, respectively. For example, glass of index 1.527would be assigned values of 89

32、.2, 93.6, and 99.4, in order ofincreasing geometry.NOTE 3Polished black glass has been reported to change in refractiveindex with time largely due to chemical contamination (10). The originalvalues can be restored by optical polishing with cerium oxide. A wedge ofhigh-purity quartz provides a more s

33、table reference standard than glass.7.2 Working StandardsCeramic tile, depolished groundopaque glass, emery paper, and other semigloss materialshaving hard and uniform surfaces are suitable when calibratedagainst a primary standard on a glossmeter known to meet theTABLE 1 Angles and Relative Dimensi

34、ons of Source Image andReceptorsIn Plane ofMeasurementPerpendicular toPlane of Measurementu, 2 tan u/2RelativeDimensionu, 2tanu/2RelativeDimensionSource image 0.75 0.0131 0.171 2.5 0.0436 0.568Tolerance 6 0.25 0.0044 0.057 0.5 0.0087 0.11460 receptor 4.4 0.0768 1.000 11.7 0.2049 2.668Tolerance6 0.1

35、0.0018 0.023 0.2 0.0035 0.04620 receptor 1.8 0.0314 0.409 3.6 0.0629 0.819Tolerance 6 0.05 0.0009 0.012 0.1 0.0018 0.02385 receptor 4.0 0.0698 0.909 6.0 0.1048 1.365Tolerance6 0.3 0.0052 0.068 0.3 0.0052 0.068D 523 89 (2008)2requirements of this test method. Such standards should bechecked periodica

36、lly for constancy by comparing with primarystandards.7.3 Store standards in a closed container when not in use.Keep them clean and away from any dirt that might scratch ormar their surfaces. Never place standards face down on asurface that may be dirty or abrasive. Always hold standards atthe side e

37、dges to avoid getting oil from the skin on the standardsurface. Clean the standards in warm water and a milddetergent solution brushing gently with a soft nylon brush. (Donot use soap solutions to clean standards, because they canleave a film.) Rinse standards in hot running water (tempera-ture near

38、 150F (65C) to remove detergent solution, followedby a final rinse in distilled water. Do not wipe standards. Thepolished black glass high-gloss standard may be dabbed gentlywith a lint-free paper towel or other lint-free absorbentmaterial. Place the rinsed standards in a warm oven to dry.8. Prepara

39、tion and Selection of Test Specimens8.1 This test method does not cover preparation techniques.Whenever a test for gloss requires the preparation of testspecimens, use the procedures given in Practice D 823.NOTE 4To determine the maximum gloss obtainable from a testmaterial, such as a paint or varni

40、sh, use Methods B or C of Practice D 823.8.2 Select specimens in accordance with Practice D 3964.9. Instrument Calibration9.1 Operate the glossmeter in accordance with the manufac-turers instructions.9.2 Verify the instrument zero by placing a black cavity inthe specified position. If the reading is

41、 not within 60.1 of zero,subtract it algebraically from subsequent readings or adjust theinstrument to read zero.9.3 Calibrate the instrument at the start and completion ofevery period of glossmeter operation, and during the operationat sufficiently frequent intervals to assure that the instrumentre

42、sponse is practically constant. To calibrate, adjust the instru-ment to read correctly the gloss of a highly polished standard,properly positioned and oriented, and then read the gloss of aworking standard in the mid-gloss range. If the instrumentreading for the second standard does not agree within

43、 one unitof its assigned values, check cleanliness and repeat. If theinstrument reading for the second standard still does not agreewithin one unit of its assigned value, repeat with anothermid-range standard. If the disparity is still more than one unit,do not use the instrument without readjustmen

44、t, preferably bythe manufacturer.10. Procedure10.1 Position each specimen in turn beneath (or on) theglossmeter. For specimens with brush marks or similar textureFIG. 1 Diagram of Parallel-Beam Glossmeter Showing Apertures and Source Mirror-Image PositionFIG. 2 Diagram of Converging-Beam Glossmeter

45、Showing Apertures and Source Mirror-Image PositionD 523 89 (2008)3effects, place them in such a way that the directions of themarks are parallel to the plane of the axes of the incident andreflected beams.10.2 Take at least three readings ona3by6-in. (75 by150-mm) area of the test specimen. If the r

46、ange is greater thantwo gloss units, take additional readings and calculate the meanafter discarding divergent results as in the section on Test forOutliers of Practice D 3980. For larger specimens, take aproportionately greater number of readings.11. Diffuse Correction11.1 Apply diffuse corrections

47、 only upon agreement be-tween the producer and the user. To apply the correction,subtract it from the glossmeter reading. To measure thecorrection, illuminate the specimen perpendicularly and viewat the incident angle with the receiver aperture specified in 6.2for the corresponding geometry. To comp

48、ute the correction,multiply the 45, 0 directional reflectance of the specimen,determined in accordance with Test Method E97,bytheeffective fraction of the luminous flux reflected by the perfectdiffuse reflector and accepted by the receiver aperture. Theluminous flux entering the receiver aperture fr

49、om the perfectwhite diffusor would give the following gloss indications foreach of the geometries:Geometry, Gloss of Perfect White Diffuser60 2.520 1.285 0.0312. Report12.1 Report the information following:12.1.1 Mean specular gloss readings and the geometry used.12.1.2 If uniformity of surface is of interest, the presence ofany specimen that exhibits gloss readings varying by more than5 % from their mean.12.1.3 Where preparation of the test specimen has beennecessary, a description or identification of the method ofpreparation.12.1.4 Manufactu