1、Designation: D 4449 08Standard Test Method forVisual Evaluation of Gloss Differences Between Surfaces ofSimilar Appearance1This standard is issued under the fixed designation D 4449; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、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. Scope1.1 This test method covers the visual evaluation of glossdifferences of coating surfaces, using special types
3、 of lamps forillumination. It identifies six aspects or types of gloss that onemay look for when using the lamp to assess gloss differencesbetween surfaces. It describes the conditions for using thelamps to best identify small differences in each of the six typesof gloss. Four levels of visual gloss
4、 differences are distin-guished.1.2 While this technique is useful for both weathered andunweathered specimens, it has not been applied to metallics.1.3 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that a
5、re provided for information onlyand are not considered standard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of whoever uses this standard to consult andestablish appropriate safety and health practices and deter-mi
6、ne the applicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 3964 Practice for Selection of Coating Specimens forAppearance MeasurementsE 284 Terminology of Appearance3. Terminology3.1 Definitions: For definitions of terms used in this method,see Terminolo
7、gy E 284.3.2 Descriptions of Terms Specific to This Standard:3.2.1 directionality of surface, nperceived change ofglossy appearance of a surface with rotation of the surface in itsown plane (see Fig. 1).3.2.2 gloss, distinctness-of-image, nperceived sharpnessof images reflected by an object surface
8、(see Fig. 2).3.2.3 gloss, of a surface, nperceived directionally selec-tive reflecting properties responsible for the degree to whichreflected highlights or images of objects may be seen assuperimposed on the surface.3.2.4 reflection haze, ncloudy or milky appearance of asurface adjacent to directio
9、ns of specular reflection (see Fig. 3).3.2.5 sheen, nperceived shininess at a near-grazing angleof incidence for an otherwise matte specimen (difficult tophotograph).3.2.6 specular gloss, nthe relative luminous reflectancefactor of a specimen in the specular direction. The luminousreflectance factor
10、 is the ratio of the luminous flux reflectedfrom, to that incident on, a specimen for specified solid angles(see Fig. 4).3.2.7 texture, nperceived structure, pattern, or topographyor combination thereof, of a surface (see Fig. 5).4. Summary of Test Method4.1 Test specimens are illuminated by special
11、 light sourcesthat provide reflected images suitable for rating the gloss ofcoating surfaces. Two types of lamps may be used to producereflected images. Lamp A consists of a modified fluorescentdesk lamp covered with screen mesh. Lamp B consists of anincandescent bare filament bulb installed in an a
12、djustable anglefixture.4.2 Light from the selected lamp illuminates the test speci-mens. The reflected images reveal specular gloss reflection; thesharpness of the images of the screen or lamp filament revealsthe detail and quality of the surface reflection (distinctness ofimage); and spreading of t
13、he reflected light into dark areas,such as the space between fluorescent tubes or near the filamentimage, reveals the presence of near-specular haze.1This test method is under the jurisdiction of ASTM Committee E12 on Colorand Appearance and is the direct responsibility of Subcommittee E12.11 on Vis
14、ualMethods.Current edition approved Dec. 1, 2008. Published December 2008. Originallyapproved in 1985. Last previous edition approved in 2004 as D 4449 90 (2004).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book
15、of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.NOTE 1The left panel is free of directionality. The right panel is highly directiona
16、l because of buffing marks.FIG. 1 Reflection of Bright Incandescent Lamp in Two PanelsNOTE 1The panels exhibit a difference in distinctness-of-reflected image.FIG. 2 Two White Porcelain Enamel PanelsD44490825. Significance and Use5.1 Gloss3is associated with the capacity of a surface toreflect more
17、light in some directions than in others. Thedirections associated with mirror (or specular) reflection nor-mally have the highest reflectances. Gloss is best seen andanalyzed when the surfaces studied are illuminated by a lightsource that provides strong contrasting patterns of light anddark. Such a
18、 light source is described in this test method.5.2 The simplest concept of gloss is that it corresponds tothe mirror-like reflectances of surfaces. However, the distribu-tions and intensities of this surface-reflected light are (for realmaterials) highly variable and affected by a variety of factors
19、:surface smoothness and contour, refractive index, absorptance,angle of incidence, and (to a generally small extent) wave-length. From the great variety of surface-reflection patterns metin materials of commerce, it has been possible to identify sevensurface-reflection criteria or “types of gloss” r
20、egularly used byskilled technologists for intercomparing and rating their prod-ucts for gloss. Six of the seven criteria, or “types of gloss,” areidentified in the section on definitions. The seventh, luster orcontrast gloss, is seldom of concern to the coatings industry.6. Apparatus6.1 Lamp AThe re
21、commended apparatus is constructedby modifying a conventional fluorescent desk lamp that hastwo 15-W, 18-in. (450-mm) tubes. Fig. 6 is a photograph; Fig.7 is a drawing of this lamp. The conventional lamp is modifiedby painting matte black the normally white reflector behind thelamp tubes. Then, afte
22、r replacing the tubes, a piece of14-in.(6.3-mm) mesh hardware cloth is fastened to the front of thereflector.6.2 Lamp BThe recommended apparatus is an incandes-cent bare filament bulb mounted on an adjustable anglefixture.47. Preparation of Specimens7.1 Since gloss is ascribable largely to the top l
23、ayer of thesurface of any given object, dirt and other surface contamina-tion significantly affect gloss. Therefore, the conditions andcare of the surface, while preparing and examining it for gloss,are critically important.7.2 Methods for preparing paint surfaces for examinationare described in Pra
24、ctice D 3964.3For a more detailed account of gloss, its measurement, and relationship toappearance generally, see R. S. Hunter and R. W. Harold, The Measurement ofAppearance, 2ndEdition , John Wiley and Sons, New York, NY, 1986.4Suitable bare filament bulbs and mounting fixtures such as a night ligh
25、t bulbmounted in a“ goose-necked” desk lamp equipped with a screw-in receptacle ormounted in a hanging lamp socket equipped with screw-in receptacle, or an autobulb, installed in an adjustable microscope lamp fixture, or a 120V 25-W tubularbulb, installed in a “goose-necked” desk lamp or installed i
26、n a hanging lamp sockethave been found suitable for this purpose.FIG. 3 Two Blue Plastic Wall Tiles Exhibiting a Difference in Reflection HazeNOTE 1The panel is polished on left end to produce higher speculargloss than the right end.FIG. 4 Panel Coated with an Automobile FinishD44490837.3 Specimen S
27、izesPreferred sizes of specimens for theindicated use are from 234 to 12 in. (70 to 300 mm) wide and512 to 16 in. (140 to 400 mm) long.8. Procedure8.1 Placement of Lamp and Specimens for StudyFromFig. 8, select the relative positions of lamp, specimen surfaces,and observer appropriate to the gloss d
28、ifferences in the speci-mens under study. Level of ambient illumination must be suchthat a photometer, placed in the specimen plane, decreases inreading with the gloss lamp turned off to less than110 the valuewith the gloss lamp on.8.2 Visual Examination of Gloss of SurfacesPlace thespecimen surface
29、s side by side. Examine the light from thegloss lamp reflected to the observer by looking for theappropriate gloss attributes described in 3.2.8.3 Interchange positions of surfaces being compared anumber of times to ensure that comparisons are free of bias asthe result of specific position relations
30、hips. Record:8.3.1 Each attribute or type of gloss for which judgment ismade.8.3.2 Nature and magnitude to the nearest whole number ofgloss difference (see 9.1.3). Add specimen identification to therecord before proceeding to the next intercomparison. Recordthe mean of two readings.9. Report9.1 Repo
31、rt the following information:9.1.1 Specimens and their method of preparation, includingany pretreatment of test surfaces by cleaning, polishing,wetting, drying, or other action.9.1.2 Lamp-specimen relationship used from those shownin Fig. 8.FIG. 5 Two Painted Panels Differing in TextureD44490849.1.3
32、 Type and magnitude of gloss differences observed.Identify differences between each pair of surfaces compared aseither:None (or indistinguishable) = 0Very slight (barely distinguishable) = 1Moderate (easily seen) = 2Considerable = 39.1.4 Which of the pair appears glossier (except in firstcase).10. P
33、recisionNOTE 1The precision study has not been completed.10.1 RepeatabilityTwo results obtained by the same op-erator should be considered suspect if they differ by more thantwo in ratings.10.2 ReproducibilityTwo results, each the mean of tworuns, obtained by operators in different laboratories shou
34、ld beconsidered suspect if they differ by more than 2.2 in ratings.NOTE 1The lamp is used to demonstrate gloss or geometric differences in the appearances of surfaces.FIG. 6 Desk LampNOTE 1The lamp is modified by the addition of a black reflecting surface behind tubes and a wire screen in front.FIG.
35、 7 Modified Desk LampD444908511. Keywords11.1 distinctness of image; gloss; haze; visual glossASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determinat
36、ion of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withd
37、rawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your
38、 comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (singl
39、e or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).(a) For high specular gloss, distinctness-of-image gloss, and reflection haze(b) For intermediate and low specular gloss and directionality of plane surfaces(c) For sheenFIG. 8 Recommended Positions of Gloss Inspection Lamp, Observer, and Surfaces of Different Levels of Gloss Being IntercomparedD4449086
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