ASTM D4449-15(2021)
(Test Method)Standard Test Method for Visual Evaluation of Gloss Differences Between Surfaces of Similar Appearance
Standard Test Method for Visual Evaluation of Gloss Differences Between Surfaces of Similar Appearance
SIGNIFICANCE AND USE
5.1 Gloss3 is associated with the capacity of a surface to reflect more light in some directions than in others. The directions associated with mirror (or specular) reflection normally have the highest reflectances. Gloss is best seen and analyzed when the surfaces studied are illuminated by a light source that provides strong contrasting patterns of light and dark. Such a light source is described in this test method.
5.2 The simplest concept of gloss is that it corresponds to the mirror-like reflectances of surfaces. However, the distributions and intensities of this surface-reflected light are (for real materials) highly variable and affected by a variety of factors: surface smoothness and contour, refractive index, absorptance, angle of incidence, and (to a generally small extent) wavelength. From the great variety of surface-reflection patterns met in materials of commerce, it has been possible to identify seven surface-reflection criteria or “types of gloss” regularly used by skilled technologists for intercomparing and rating their products for gloss. Six of the seven criteria, or “types of gloss,” are identified in the section on definitions. The seventh, luster or contrast gloss, is seldom of concern to the coatings industry.
SCOPE
1.1 This test method covers the visual evaluation of gloss differences of coating surfaces, using special types of lamps for illumination. It identifies six aspects or types of gloss that one may look for when using the lamp to assess gloss differences between surfaces. It describes the conditions for using the lamps to best identify small differences in each of the six types of gloss. Four levels of visual gloss differences are distinguished.
1.2 While this technique is useful for both weathered and unweathered specimens, it has not been applied to metallics.
1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of whoever uses this standard to consult and establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation:D4449 −15 (Reapproved 2021)
Standard Test Method for
Visual Evaluation of Gloss Differences Between Surfaces of
Similar Appearance
This standard is issued under the fixed designation D4449; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope E284 Terminology of Appearance
1.1 This test method covers the visual evaluation of gloss
3. Terminology
differencesofcoatingsurfaces,usingspecialtypesoflampsfor
illumination. It identifies six aspects or types of gloss that one 3.1 Definitions—For definitions of terms used in this
may look for when using the lamp to assess gloss differences method, see Terminology E284.
between surfaces. It describes the conditions for using the
3.2 Definitions of Terms Specific to This Standard:
lamps to best identify small differences in each of the six types
3.2.1 directionality of surface, n—perceived change of
of gloss. Four levels of visual gloss differences are distin-
glossyappearanceofasurfacewithrotationofthesurfaceinits
guished.
own plane (see Fig. 1).
1.2 While this technique is useful for both weathered and
3.2.2 gloss, distinctness-of-image, n—perceived sharpness
unweathered specimens, it has not been applied to metallics.
of images reflected by an object surface (see Fig. 2).
1.3 The values stated in inch-pound units are to be regarded
3.2.3 gloss, of a surface, n—perceived directionally selec-
as standard. The values given in parentheses are mathematical
tive reflecting properties responsible for the degree to which
conversions to SI units that are provided for information only
reflected highlights or images of objects may be seen as
and are not considered standard.
superimposed on the surface.
1.4 This standard does not purport to address all of the
3.2.4 reflection haze, n—cloudy or milky appearance of a
safety concerns, if any, associated with its use. It is the
surfaceadjacenttodirectionsofspecularreflection(seeFig.3).
responsibility of whoever uses this standard to consult and
3.2.5 sheen, n—perceived shininess at a near-grazing angle
establish appropriate safety, health, and environmental prac-
of incidence for an otherwise matte specimen (difficult to
tices and determine the applicability of regulatory limitations
photograph).
prior to use.
3.2.6 specular gloss, n—the relative luminous reflectance
1.5 This international standard was developed in accor-
factor of a specimen in the specular direction. The luminous
dance with internationally recognized principles on standard-
reflectance factor is the ratio of the luminous flux reflected
ization established in the Decision on Principles for the
from, to that incident on, a specimen for specified solid angles
Development of International Standards, Guides and Recom-
(see Fig. 4).
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee. 3.2.7 texture, n—perceived structure, pattern, or topography
or combination thereof, of a surface (see Fig. 5).
2. Referenced Documents
4. Summary of Test Method
2.1 ASTM Standards:
D3964 Practice for Selection of Coating Specimens for
4.1 Test specimens are illuminated by special light sources
Appearance Measurements
that provide reflected images suitable for rating the gloss of
coating surfaces. Two types of lamps may be used to produce
reflected images. Lamp A consists of a modified fluorescent
This test method is under the jurisdiction of ASTM Committee E12 on Color
desk lamp covered with screen mesh. Lamp B consists of an
and Appearance and is the direct responsibility of Subcommittee E12.11 on Visual
Methods.
incandescent bare filament bulb installed in an adjustable angle
Current edition approved June 1, 2021. Published June 2021. Originally
fixture.
approved in 1985. Last previous edition approved in 2015 as D4449 – 15. DOI:
10.1520/D4449-15R21.
4.2 Light from the selected lamp illuminates the test speci-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
mens.The reflected images reveal specular gloss reflection; the
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
sharpness of the images of the screen or lamp filament reveals
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. the detail and quality of the surface reflection (distinctness of
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4449−15 (2021)
NOTE 1—The left panel is free of directionality. The right panel is highly directional because of buffing marks.
FIG. 1Reflection of Bright Incandescent Lamp in Two Panels
NOTE 1—The panels exhibit a difference in distinctness-of-reflected image.
FIG. 2Two White Porcelain Enamel Panels
image); and spreading of the reflected light into dark areas,
D4449−15 (2021)
FIG. 3Two Blue Plastic Wall Tiles Exhibiting a Difference in Reflection Haze
NOTE 1—The panel is polished on left end to produce higher specular
gloss than the right end.
FIG. 4Panel Coated with an Automobile Finish
suchasthespacebetweenfluorescenttubesornearthefilament source that provides strong contrasting patterns of light and
image, reveals the presence of near-specular haze. dark. Such a light source is described in this test method.
5.2 The simplest concept of gloss is that it corresponds to
5. Significance and Use
the mirror-like reflectances of surfaces. However, the distribu-
5.1 Gloss is associated with the capacity of a surface to
tions and intensities of this surface-reflected light are (for real
reflect more light in some directions than in others. The
materials) highly variable and affected by a variety of factors:
directions associated with mirror (or specular) reflection nor-
surface smoothness and contour, refractive index, absorptance,
mally have the highest reflectances. Gloss is best seen and
angle of incidence, and (to a generally small extent) wave-
analyzed when the surfaces studied are illuminated by a light
length.Fromthegreatvarietyofsurface-reflectionpatternsmet
inmaterialsofcommerce,ithasbeenpossibletoidentifyseven
surface-reflection criteria or “types of gloss” regularly used by
For a more detailed account of gloss, its measurement, and relationship to
skilled technologists for intercomparing and rating their prod-
appearance generally, see R. S. Hunter and R. W. Harold, The Measurement of
nd
Appearance, 2 Edition, John Wiley and Sons, New York, NY, 1986. ucts for gloss. Six of the seven criteria, or “types of gloss,” are
D4449−15 (2021)
FIG. 5Two Painted Panels Differing in Texture
identified in the section on definitions. The seventh, luster or care of the surface, while preparing and examining it for gloss,
contrast gloss, is seldom of concern to the coatings industry. are critically important.
7.2 Methods for preparing paint surfaces for examination
6. Apparatus
are described in Practice D3964.
6.1 LampA—The recommended apparatus is constructed by
7.3 Specimen Sizes—Preferred sizes of specimens for the
modifying a conventional fluorescent desk lamp that has two
indicated use are from 2 ⁄4 to 12 in. (70 to 300 mm) wide and
15-W, 18-in. (450-mm) tubes. Fig. 6 is a photograph; Fig. 7 is
5 ⁄2 to 16 in. (140 to 400 mm) long.
a drawing of this lamp. The conventional lamp is modified by
painting matte black the normally white reflector behind the
8. Procedure
lamp tubes. Then, after replacing the tubes,
...
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