1、Designation: D4449 15Standard Test Method forVisual Evaluation of Gloss Differences Between Surfaces ofSimilar Appearance1This standard is issued under the fixed designation D4449; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, th
2、e 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 o
3、f 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 d
4、ifferences 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 are
5、 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-mine
6、 the applicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D3964 Practice for Selection of Coating Specimens forAppearance MeasurementsE284 Terminology of Appearance3. Terminology3.1 DefinitionsFor definitions of terms used in thismethod, see Terminology E28
7、4.3.2 Definitions 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 (see Fig
8、. 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 directions of sp
9、ecular 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 is the
10、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 light s
11、ourcesthat 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 adjustabl
12、e 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 the refle
13、cted 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 VisualMetho
14、ds.Current edition approved April 1, 2015. Published June 2015. Originallyapproved in 1985. Last previous edition approved in 2008 as D4449 08. DOI:10.1520/D4449-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Bo
15、ok of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1NOTE 1The left panel is free of directionality. The right panel is highly directio
16、nal 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 PanelsD4449 1525. Significance and Use5.1 Gloss3is associated with the capacity of a surface toreflect mo
17、re 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. Suc
18、h a 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 fact
19、ors: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
20、” regularly 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
21、 recommended apparatus is constructed bymodifying a conventional fluorescent desk lamp that has two15-W, 18-in. (450-mm) tubes. Fig. 6 is a photograph; Fig. 7 isa drawing of this lamp. The conventional lamp is modified bypainting matte black the normally white reflector behind the3For a more detaile
22、d 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.FIG. 3 Two Blue Plastic Wall Tiles Exhibiting a Difference in Reflection HazeNOTE 1The panel is polished
23、on left end to produce higher speculargloss than the right end.FIG. 4 Panel Coated with an Automobile FinishD4449 153lamp tubes. Then, after 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-c
24、ent bare filament bulb mounted on an adjustable anglefixture.47. Preparation of Specimens7.1 Since gloss is ascribable largely to the top layer of thesurface of any given object, dirt and other surface contamina-tion significantly affect gloss. Therefore, the conditions andcare of the surface, while
25、 preparing and examining it for gloss,are critically important.7.2 Methods for preparing paint surfaces for examinationare described in Practice D3964.7.3 Specimen SizesPreferred 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.
26、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 differences in the speci-mens under study. Level of ambient illumination must be suchthat a photometer, placed in the specimen plane, de
27、creases 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 surfaces side by side. Examine the light from thegloss lamp reflected to the observer by looking for theappropriate gloss attributes described
28、 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 relationships. 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 ofg
29、loss difference (see 9.1.3). Add specimen identification to therecord before proceeding to the next intercomparison. Recordthe mean of two readings.9. Report9.1 Report the following information:4Suitable bare filament bulbs and mounting fixtures such as a night light bulbmounted in a“ goose-necked”
30、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 in a hanging lamp sockethave been f
31、ound suitable for this purpose.FIG. 5 Two Painted Panels Differing in TextureD4449 1549.1.1 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. 8.9.
32、1.3 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
33、. Precision and Bias10.1 The precision of this test method is based on aninterlaboratory study of ASTM D4449, Standard Test Methodfor Visual Evaluation of Gloss Differences Between Surfacesof Similar Appearance, conducted in 2013. Observers from 16laboratories participated in this study. Each of the
34、 observerswas asked to report the gloss difference rating of 16 samples(representing eight pairs of blind duplicates). Every “testNOTE 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
35、reflecting surface behind tubes and a wire screen in front.FIG. 7 Modified Desk LampD4449 155(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
36、 Inspection Lamp, Observer, and Surfaces of Different Levels of Gloss Being IntercomparedFIG. 9 Probability of Scale Value versus Gloss DifferenceD4449 156result” reported represents an individual gloss difference de-termination. The data was analyzed to determine the probabil-ity of an observer rep
37、orting a given rating based uponcalculated absolute gloss differences for each duplicate samplepair;5the details are given in ASTM Research Report No.RR:E12-1008.610.2 Probability of Scale Value versus Gloss Difference(Fig. 9):10.2.1 Calculated absolute gloss difference=|gloss1-gloss2|for example: |
38、45-37|=8.10.2.2 Calculated probability of scale value based on ob-servers responses at each gloss difference levels.10.2.2.1 Probability of scale 3 at gloss difference 27 andabove is more than 0.7.10.2.2.2 Probability of scale 0 at gloss difference 20 andabove is zero.10.2.2.3 Probability of scale 2
39、 at gloss difference 20 is about0.6.(1) There is an uncertainty in scale 2 and 3 at glossdifference 20.10.2.2.4 Probability of scale 3 at gloss difference 8 andbelow is less than 0.1.(1) There is uncertainty in scale 0 and 1 at gloss difference7to8.NOTE 1The term scale is used as an alternative term
40、 for magnitude.10.3 Sensitivity of Visual Scaling Based on DuplicateSamples (Fig. 10):10.3.1 Calculated probability of scale value based on ob-servers responses at each gloss level for duplicate samples.10.3.1.1 Probability of scale 3 is zero for duplicate samplesat all gloss levels.10.3.1.2 Probabi
41、lity of scale 0 is more than 0.6 at glosslevels 37 and 73.(1) There is uncertainty in scale 0 and 1 at gloss level 45and 66.10.4 The precision statement was determined through sta-tistical examination of 256 results, from 16 observers on 8pairs of samples (described in the following table).No. Sampl
42、e 60 Gloss Duplicates Pairs1 A 46.0 F-A P-I2 B 73.1 E-B O-K3 C 65.8 H-C M-J4 D 37.4 G-D N-L5 E 72.86 F 46.57 G 37.78 H 65.99 I 44.410 J 65.411 K 73.112 L 36.613 M 65.114 N 36.915 O 72.516 P 45.010.5 There are several factors causing variation in observ-ers responses including, but not limited to:10.
43、5.1 Nature of visual experiment as a subjective experi-ment.10.5.2 Inconsistencies in illumination/viewing geometrywithin laboratories.10.5.3 Observers at different levels of experience.5Data analysis completed by Mahnaz Mohammadi, Axalta Coating Systems,onFebruary 13, 2014.6Supporting data have bee
44、n filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:E12-1008. ContactASTM CustomerService at serviceastm.org.FIG. 10 Probability of Scale Value versus Gloss Level for Duplicate SamplesD4449 15710.5.4 Ordinal-based experiment instead of scaling.11. Keywords1
45、1.1 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 determination of the validity of any such patent rig
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