ASTM_D_4449_-_15.pdf

Designation:D444915Standard 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,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 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 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 are provided for information onlyand are not considered standard.1.4This 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 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 E284.3.2 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.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 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 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 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 adjustable 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 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 VisualMethods.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 Book 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 States1 NOTE1The left panel is free of directionality.The right panel is highly directional because of buffing marks.FIG.1 Reflection of Bright Incandescent Lamp in Two PanelsNOTE1The panels exhibit a difference in distinctness-of-reflected image.FIG.2 Two White Porcelain Enamel PanelsD4449 152 5.Significance and Use5.1 Gloss3is associated with the capacity 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.Gloss is best seen andanalyzed when the surfaces studied are illuminated by a lightsource that provides strong contrasting patterns o