ASTM D2457-97
(Test Method)Standard Test Method for Specular Gloss of Plastic Films and Solid Plastics
Standard Test Method for Specular Gloss of Plastic Films and Solid Plastics
SCOPE
1.1 This test method describes procedures for the measurement of gloss of plastic films and solid plastics, both opaque and transparent. It contains three separate gloss angles (Note 1):
1.1.1 60-deg, recommended for intermediate-gloss films,
1.1.2 20-deg, recommended for high-gloss films, and
1.1.3 45-deg, recommended for intermediate and low-gloss films.
Note 1-The 60-deg and 20-deg apparatus and method of measurement duplicate those in Test Method D 523; those for the 45° procedure are similarly taken from Test Method C 346.
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Note 2- There is no similar or equivalent ISO standard.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 2457 – 97
Standard Test Method for
Specular Gloss of Plastic Films and Solid Plastics
This standard is issued under the fixed designation D 2457; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.2.1 specular gloss, n—(1) ratio of flux reflected in specu-
lar direction to incident flux for a specified angle of incidence
1.1 This test method describes procedures for the measure-
and source and receptor angular apertures. (2) perceived
ment of gloss of plastic films and solid plastics, both opaque
surface brightness associated with the luminous specular (regu-
and transparent. It contains three separate gloss angles (Note
lar) reflection of a surface. (CIE)
1):
3.2.2 gloss reflectance factor, R , n—ratio of the specularly
S
1.1.1 60-deg, recommended for intermediate-gloss films,
reflected part of the (whole) flux reflected from the specimen to
1.1.2 20-deg, recommended for high-gloss films, and
the flux reflected from a specified gloss standard under the
1.1.3 45-deg, recommended for intermediate and low-gloss
same geometric and spectral conditions of measurement.
films.
3.2.2.1 Discussion—The gloss standard may be a black
NOTE 1—The 60-deg and 20-deg apparatus and method of measure-
glass or a mirror and may be assigned one of a variety of scale
ment duplicate those in Test Method D 523; those for the 45° procedure
values as specified.
are similarly taken from Test Method C 346.
4. Significance and Use
1.2 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4.1 Specular gloss is used primarily as a measure of the
responsibility of the user of this standard to establish appro-
shiny appearance of films and surfaces. Precise comparisons of
priate safety and health practices and determine the applica-
gloss values are meaningful only when they refer to the same
bility of regulatory limitations prior to use.
measurement procedure and same general type of material. In
particular, gloss values for transparent films should not be
NOTE 2—There is no similar or equivalent ISO standard.
compared with those for opaque films, and vice versa. Gloss is
2. Referenced Documents
a complex attribute of a surface which cannot be completely
measured by any single number.
2.1 ASTM Standards:
4.2 Specular gloss usually varies with surface smoothness
C 346 Test Method for 45° Specular Gloss of Ceramic
and flatness. It is sometimes used for comparative measure-
Materials
ments of these surface properties.
D 523 Test Method for Specular Gloss
E 284 Terminology of Appearance
5. Apparatus
E 691 Practice for Conducting an Interlaboratory Study to
5.1 Instrumental Components—Each apparatus (Note 3)
Determine the Precision of a Test Method
shall consist of an incandescent light source furnishing an
E 1347 Test Method for Color and Color-Difference Mea-
incident beam, means for locating the surface of the specimen,
surement by Tristimulus (Filter) Colorimetry
and a receptor located to receive the required pyramid of rays
E 1349 Test Method for Reflectance Factor and Color by
reflected by the specimen. The receptor shall be a photosensi-
Spectrophotometry Using Bidirectional Geometry
tive device responding to visible radiation.
3. Terminology
NOTE 3—The 60 and 20-deg procedures require apparatus identical to
3.1 Definitions—For definitions of terms used in this test
that specified in Test Method D 523. The 45° procedure requires apparatus
method, see Terminology E 1284. like that specified in Test Method C 346.
3.2 Definitions of Terms Specific to This Standard:
5.2 Geometric Conditions—The axis of the incident beam
shall be at one of the specified angles from the perpendicular to
the specimen surface. The axis of the receptor shall be at the
This test method is under the jurisdiction of ASTM Committee D-20 on Plastics
and is the direct responsibility of Subcommittee D20.40 on Optical Properties.
mirror reflection of the axis of the incident beam. With a flat
Current edition approved Jan. 10, 1997. Published May 1997. Originally
piece of polished black glass or other front-surface mirror in
published as D 2457 – 65 T. Last previous edition D 2457 – 90.
specimen position, an image of the source shall be formed at
Annual Book of ASTM Standards, Vol 02.05.
Annual Book of ASTM Standards, Vol 06.01. the center of the receptor field stop (receptor window). The
Annual Book of ASTM Standards, Vol 14.02.
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NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 2457
length of the illuminated area of the specimen shall be equal to 7. Preparation and Selection of Test Specimens
not more than one third of the distance from the center of this
7.1 This test method does not cover preparation techniques.
area to the receptor field stop. The angular dimensions and
Whenever a test for gloss requires the preparation of a test
tolerances of the geometry of the source and receptor shall be
specimen, report the technique of specimen preparation.
as indicated in Table 1. The angular dimensions of the receptor
7.2 Specimen surfaces shall have good planarity, since
field stop are measured from the center of the test surface. The
surface warpage, waviness, or curvature may seriously affect
angular dimensions of the source field stop are mostly easily
test results. The directions of machine marks, or similar texture
measured by the specimen-to-window angular size of the
effects, shall be parallel to the plane of the axes of the two
mirror image of the source formed in the receptor field stop.
beams, unless otherwise specified. (Note that this does not
(See Fig. 1 for a generalized illustration of the dimensions.)
avoid the second-surface reflection.)
The tolerances are chosen so that errors of no more than one
7.3 Surface test areas shall be kept free of soil and abrasion.
gloss unit at any point on the scale will result from errors in the
Gloss is due chiefly to reflection at the surface; therefore,
source and receptor aperture.
anything that changes the surface physically or chemically is
5.3 Vignetting—There shall be no vignetting of rays that lie
likely to affect gloss.
within the field angles specified in 5.2.
8. Mounting Films for Measurement
5.4 Spectral Conditions—Results should not differ signifi-
8.1 Any nonrigid film must be mounted in a device that will
cantly from those obtained with a source-filter-photocell com-
hold it flat, but will not stretch the film while it is measured.
bination that is spectrally corrected to yield CIE luminous
Three different filmholding devices have each proved satisfac-
efficiency with CIE Source C. Since specular reflection is, in
tory for at least some types of films:
general, spectrally nonselective, spectral corrections need be
8.1.1 Vacuum Plate (see Fig. 2) is required for stiff films.
applied only to highly chromatic, low-gloss specimens upon
Connect the vacuum plate by rubber tube to a vacuum pump or
agreement of users of this test method.
vacuum line. With thin, soft films it is sometimes necessary to
5.5 Measurement Mechanism—The receptor-measurement
use a valve and pressure gage and to limit the vacuum so as to
mechanism shall give a numerical indication that is propor-
keep from collapsing the soft film into the pores of the ground
tional to the light flux passing the receptor field stop within 61
plate.
percent of full-scale reading.
8.1.2 Flat Plate with two-side pressure-sensitive tape (see
6. Reference Standards Fig. 3). Make sure each specimen is pulled smooth, but not
stretched before holding it by the two strips of adhesive tape.
6.1 Primary Working Standards may be highly polished,
Replace the tape whenever it loses its adhesiveness.
plane, black glass surfaces. The specular reflectance, in per-
8.1.3 Telescoping Ring or Hoop (see Fig. 4)—To mount the
cent, (R ) of such surfaces shall be computed by the following
s
specimen in the telescoping ring, lay the flexible film over the
equation:
base (male) section and drop the top over the base. Push down
R ~percent! 5
s
carefully, taking care to pull the test film taut without stretching
2 2
cos i 2 =n 2 sin i
it. Measure the taut area.
FF G
2 2
cos i 1 =n 2 sin i
8.2 Backing for Films That Transmit Light—A matt black
2 2 2
backing or (even better) a black cavity must be placed behind
n cos i 2 n 2 sin i
=
1 (1)
F G G
any film that transmits light. Erroneous measurements will
2 2 2
n cos i 1 n 2 sin i
=
occur without a suitable trap or backing.
where:
9. Procedure
i = the specular (incidence) angle, and
9.1 Operate the glossmeter in accordance with the manufac-
n = the index of refraction of the surface.
turer’s instructions.
Multiply the computed R at each angle by the scale factors
s
9.2 Calibrate the instrument at the start and completion of
shown in Table 2.
every period of glossmeter operation and during the operation
NOTE 4—On the 45 and 60° scales, a perfect mirror measures 1000.
at sufficiently frequent intervals to assure that the instrument
6.2 Secondary Working Standards of ceramic tile, glass,
response is practically constant. If at any time an instrument
porcelain enamel, or other materials having hard, flat, and fails to repeat readings of the standard to within 2 percent of
uniform surfaces may be calibrated from the primary standard
the prior setting, the intervening results should be rejected. To
on a glossmeter determined to be in strict conformance with the calibrate, adjust the instrument to read correctly the gloss of a
requirements prescribed in 5.2. highly polished standard, and then read the gloss of a standard
TABLE 1 Angular Dimensions and Tolerances of Geometry of Source and Receptor Field Stops
Source Field Stop Receptor Field Stop
In Plane of Measurement, Perpendicular to Plane of Perpendicular to Plane of
Geometry, deg Incidence Angle, deg In Plane of Measurement, deg
deg Measurement, deg Measurement, deg
60 60 6 0
...
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