ASTM C346-87(2018)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: C346 − 87 (Reapproved 2018)
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 Scope Filter Reflectometry (Withdrawn 1991)
1.1 This test method covers the determination of the specu-
3. Terminology
lar gloss of porcelain enameled specimens, but may be appli-
3.1 Definitions:
cable to other specimens having similar reflection characteris-
3.1.1 specular gloss—ratio of reflected to incident light,
tics. This test method may be used to compare the gloss of
times 1000, for specified apertures of illumination and recep-
porcelain enameled specimens or to provide an index of acid or
tion when the axis of reception coincides with the mirror image
abrasion resistance by measurement of gloss loss.
of the axis of illumination.
NOTE 1—Specular gloss is one of several related appearance attributes
NOTE 3—In this operational definition, the quantity defined as specular
that produce the sensation of glossiness. For this reason, specular gloss
gloss is composed of surface-reflected and body-reflected components.
measurements may not always correlate well with visual rankings of
For some low-gloss measurements, an approximate evaluation of the
glossiness.
surface-reflected component of specular gloss may be required (see
NOTE 2—Improved correlations with visual judgments can sometimes
Section 9).
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
3.1.2 45-deg specular gloss—fraction of visible light inci-
geometries. Values generally cannot be predicated for one geometry from
dent upon the specimens at 45° to the normal that is reflected
measurements made with another.
in the direction of mirror reflection.
1.2 This standard does not purport to address all of the
NOTE 4—Under ideal conditions, the incident beam should consist of
safety concerns, if any, associated with its use. It is the
parallel light, and only light reflected in the true direction of mirror
responsibility of the user of this standard to establish appro-
reflection should be accepted for measurement.
priate safety, health, and environmental practices and deter-
3.1.3 source aperture—angular size (solid angle) of the light
mine the applicability of regulatory limitations prior to use.
source (lamp filament, if an incandescent source is used)
1.3 This international standard was developed in accor-
measured from the center of the incident beam lens.
dance with internationally recognized principles on standard-
3.1.4 receptor aperture—angular size (solid angle) of the
ization established in the Decision on Principles for the
receptor window, measured from the center of the receptor
Development of International Standards, Guides and Recom-
lens.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
4. Significance and Use
2. Referenced Documents 4.1 This test method may be used to compare the gloss of
2 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
5.1 Instrumental Components—The apparatus shall consist
of an incandescent light source and lens furnishing an incident
This test method is under the jurisdiction of ASTM Committee B08 on Metallic
beam of rays of required aperture, means for locating the
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.12 on
surface of the specimen, and a receptor located to receive the
Materials for Porcelain Enamel and Ceramic-Metal Systems. 19th St., Suite 200,
Arlington, VA 22209. required pyramid of rays reflected from the specimen. The
Current edition approved Oct. 1, 2018. Published October 2018. Originally
receptor shall be a photosensitive device having maximum
approved in 1954. Last previous edition approved in 2014 as C346 – 87 (2014).
response near the middle of the visible region of the spectrum.
DOI: 10.1520/C0346-87R18.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
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C346 − 87 (2018)
5.2 Geometric Conditions—The axis of the incident beam 8. Procedure
shall be 45° from the perpendicular to the specimen surface.
8.1 Operate the glossmeter according to the instructions of
The axis of the receptor beam shall be coincident with the
the manufacturer.
mirror image of the axis of the incident beam. A flat piece of
8.2 Set the instrument to read the assigned gloss value of a
polished black glass in the specimen position shall form an
highly polished working standard; then read the gloss of lower
image of the source in the center of the receptor window. The
glass standards having poorer image-forming characteristics. If
angular dimensions of the source and receptor shall be as
the instrument readings for the latter standards do not agree
specified below:
with the assigned values to within two gloss units, the
In Plane of Perpendicular to Plane
A A
instrument optics may require readjustment; preferably, this
Apertures Measurement, deg of Measurement, deg
Source 1.4 ± 0.4 3.0 ± 1.0 should be done by the manufacturer.
Receiver 8.0 ± 0.1 10.0 ± 0.2
8.3 Measure the gloss of at least three portions of each
specimen surface. This will give an indication of gloss unifor-
mity.
A
“Plane of measurement” is the plane containing axes of illuminating and viewing
beams.
8.4 For evaluation of change of gloss of a single specimen,
which may be used as
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