ASTM C346-87(2014)
(Test Method)Standard Test Method for 45-deg Specular Gloss of Ceramic Materials
Standard Test Method for 45-deg Specular Gloss of Ceramic Materials
SIGNIFICANCE AND USE
4.1 This test method may be used to compare the gloss of porcelain enamel, ceramic, and other finishes or to provide a comparison of their resistance to attack from acid, alkali, or other environmental factors by measurement of gloss loss.
SCOPE
1.1 This test method covers the determination of the specular gloss of porcelain enameled specimens, but may be applicable to other specimens having similar reflection characteristics. This test method may be used to compare the gloss of porcelain enameled specimens or to provide an index of acid or abrasion resistance by measurement of gloss loss. Note 1—Specular gloss is one of several related appearance attributes that produce the sensation of glossiness. For this reason, specular gloss measurements may not always correlate well with visual rankings of glossiness. Note 2—Improved correlations with visual judgments can sometimes be achieved by the use of instruments with different geometries than those specified herein. Refer to Test Method D523 for 20, 60, and 85-deg geometries. Values generally cannot be predicated for one geometry from measurements made with another.
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.
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Designation: C346 − 87 (Reapproved 2014)
Standard Test Method for
45-deg Specular Gloss of Ceramic Materials
This standard is issued under the fixed designation C346; 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 tionwhentheaxisofreceptioncoincideswiththemirrorimage
of the axis of illumination.
1.1 This test method covers the determination of the specu-
lar gloss of porcelain enameled specimens, but may be appli-
NOTE 3—In this operational definition, the quantity defined as specular
gloss is composed of surface-reflected and body-reflected components.
cable to other specimens having similar reflection characteris-
For some low-gloss measurements, an approximate evaluation of the
tics. This test method may be used to compare the gloss of
surface-reflected component of specular gloss may be required (see
porcelainenameledspecimensortoprovideanindexofacidor
Section 9).
abrasion resistance by measurement of gloss loss.
3.1.2 45-deg specular gloss—fraction of visible light inci-
NOTE 1—Specular gloss is one of several related appearance attributes
dent upon the specimens at 45° to the normal that is reflected
that produce the sensation of glossiness. For this reason, specular gloss
in the direction of mirror reflection.
measurements may not always correlate well with visual rankings of
glossiness.
NOTE 4—Under ideal conditions, the incident beam should consist of
NOTE 2—Improved correlations with visual judgments can sometimes
parallel light, and only light reflected in the true direction of mirror
be achieved by the use of instruments with different geometries than those
reflection should be accepted for measurement.
specified herein. Refer to Test Method D523 for 20, 60, and 85-deg
3.1.3 source aperture—angularsize(solidangle)ofthelight
geometries. Values generally cannot be predicated for one geometry from
source (lamp filament, if an incandescent source is used)
measurements made with another.
measured from the center of the incident beam lens.
1.2 This standard does not purport to address all of the
3.1.4 receptor aperture—angular size (solid angle) of the
safety concerns, if any, associated with its use. It is the
receptor window, measured from the center of the receptor
responsibility of the user of this standard to establish appro-
lens.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
4. Significance and Use
2. Referenced Documents
4.1 This test method may be used to compare the gloss of
porcelain enamel, ceramic, and other finishes or to provide a
2.1 ASTM Standards:
comparison of their resistance to attack from acid, alkali, or
D523 Test Method for Specular Gloss
other environmental factors by measurement of gloss loss.
E97 Method of Test for Directional Reflectance Factor,
45-Deg 0-Deg, of Opaque Specimens by Broad-Band
5. Apparatus
Filter Reflectometry (Withdrawn 1991)
5.1 Instrumental Components—The apparatus shall consist
3. Terminology
of an incandescent light source and lens furnishing an incident
beam of rays of required aperture, means for locating the
3.1 Definitions:
surface of the specimen, and a receptor located to receive the
3.1.1 specular gloss—ratio of reflected to incident light,
required pyramid of rays reflected from the specimen. The
times 1000, for specified apertures of illumination and recep-
receptor shall be a photosensitive device having maximum
response near the middle of the visible region of the spectrum.
This test method is under the jurisdiction ofASTM Committee B08 on Metallic
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.12 on
5.2 Geometric Conditions—The axis of the incident beam
Materials for Porcelain Enamel and Ceramic-Metal Systems. 19th St., Suite 200,
shall be 45° from the perpendicular to the specimen surface.
Arlington, VA 22209.
The axis of the receptor beam shall be coincident with the
Current edition approved May 1, 2014. Published May 2014. Originally
approved in 1954. Last previous edition approved in 2009 as C346 – 87 (2009).
mirror image of the axis of the incident beam. A flat piece of
DOI: 10.1520/C0346-87R14.
polished black glass in the specimen position shall form an
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
image of the source in the center of the receptor window. The
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
angular dimensions of the source and receptor shall be as
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
specified below:
The last approved version of this historical standard is referenced on
www.astm.org.
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C346 − 87 (2014)
8.2 Set the instrument to read the assigned gloss value of a
highly polished working standard; then read the gloss of lower
glass standards having poorer image-forming characteristics. If
In Plane of Perpendicular to Plane
A A
Apertures Measurement, deg of Measurement, deg
the instrument readings for the latter standards do not agree
Source 1.4 ± 0.4 3.0 ± 1.0
with the assigned values to within two gloss units, the
Receiver 8.0 ± 0.1 10.0 ± 0.2
instrument optics may require readjustment; preferably, this
should be done by the manufacturer.
A
“Plane of measurement” is the plane containing axes of illuminating and viewing
8.3 Measure the gloss of at least three portions of each
beams.
specimen surface. This will give an indication of gloss unifor-
mity.
8.4 For evaluation of change of gloss of a single specimen,
which may be used as a measurement of surface deterioration
6. Specular Gloss Standards
of porcelain enameled or ceramic specimens, exercise particu-
6.1 Specular Gloss Standards— Primary working standards
lar care to see that the glossmeter is in exactly the same
shall be
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