ASTM E430-97
(Test Method)Standard Test Methods for Measurement of Gloss of High-Gloss Surfaces by Goniophotometry
Standard Test Methods for Measurement of Gloss of High-Gloss Surfaces by Goniophotometry
SCOPE
1.1 These test methods cover the measurement of the reflection characteristics responsible for the glossy appearance of high-gloss surfaces. Two test methods, A and B, are provided for evaluating such surface characteristics at specular angles of 30° and 20°, respectively. These test methods are not suitable for diffuse finish surfaces nor do they measure color, another appearance attribute.
1.2 As originally developed by Tingle and others (see Refs 1 and 2), the test methods were applied only to bright metals. Recently they have been applied to high-gloss automotive finishes and other nonmetallic surfaces.
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Designation: E 430 – 97
Standard Test Methods for
Measurement of Gloss of High-Gloss Surfaces by
Goniophotometry
This standard is issued under the fixed designation E 430; 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 (1) Discussion—The term reflectance is often used in a
general sense or as an abbreviation for reflectance factor. Such
1.1 These test methods cover the measurement of the
usage is not assumed in this method. The definition may
reflection characteristics responsible for the glossy appearance
require that the term be modified by adjectives denoting the
of high-gloss surfaces. Two test methods, A and B, are
spectral and geometric conditions of measurement.
provided for evaluating such surface characteristics at specular
3.1.1.2 reflectance factor, R, n—ratio of the flux reflected
angles of 30° and 20°, respectively. These test methods are not
from the specimen to the flux reflected from the perfect
suitable for diffuse finish surfaces nor do they measure color,
reflecting diffuser under the same spectral and geometric
another appearance attribute.
conditions of measurement. (E 284)
1.2 As originally developed by Tingle and others (see Refs
2 3.1.1.3 gloss reflectance factor, R,n—ratio of the specu-
1 and 2), the test methods were applied only to bright metals. s
larly reflected part of the (whole) flux reflected from the
Recently they have been applied to high-gloss automotive
specimen to the flux reflected from a specified gloss standard
finishes and other nonmetallic surfaces.
under the same geometric and spectral conditions of measure-
2. Referenced Documents ment.
(1) Discussion—The gloss standard may be a black glass or
2.1 ASTM Standards:
a mirror, and may be assigned one of a variety of scale values
D 523 Test Method for Specular Gloss
G as specified. (E 284)
D 2457 Test Method for Specular Gloss of Plastic Films and s
3.1.2 Gloss and Types of Gloss:
Solid Plastics
3.1.2.1 gloss, n—angular selectivity of reflected light, re-
E 171 Specification for Standard Atmospheres for Condi-
sponsible for the degree to which reflected highlights or images
tioning and Testing Flexible Barrier Materials
of objects may be seen as superimposed on a surface. (E 284)
E 179 Guide for Selection of Geometric Conditions for
(1) Discussion—Gloss is responsible for the object’s glossy
Measurement of Reflectance and Transmission Properties
appearance, not for an observer’s perception of the appearance.
of Materials
At least six types or characteristics of gloss may be observed
E 284 Terminology of Appearance
depending upon the character of the surface and the spatial
E 308 Practice for Computing the Colors of Objects by
distribution of the reflected light (3).
Using the CIE System
3.1.2.2 specular gloss, n—ratio of flux reflected in specular
E 1347 Test Method for Color and Color-Difference Mea-
direction to incident flux for a specified angle of incidence and
surement of Object-Color Specimens by Tristimulus
source and receptor angular apertures. (E 284)
(Filler) Colormetry
3.1.2.3 distinctness-of-image gloss, n—aspect of gloss char-
3. Terminology
acterized by the sharpness of images of objects produced by
reflection at a surface. (E 284)
3.1 Definitions:
3.1.2.4 sheen, n—the specular gloss at a large angle of
3.1.1 Reflectance and Related Terms:
incidence for an otherwise matte specimen. (The usual angle
3.1.1.1 reflectance, r,n—ratio of the reflected radiant or
for measurement is 85°.) (E 284)
luminous flux to the incident flux in the given conditions.
3.1.3 Terms Relating to Surface Characteristics:
(E 284)
3.1.3.1 directionality, n—perceived, the degree to which the
appearance of a surface changes as the surface is rotated in its
These test methods are under the jurisdiction of ASTM Committee E-12 on
own plane, under fixed conditions of illumination and viewing.
Appearance and are the direct responsibility of Subcommittee E 12.03 on Geometry.
Current edition approved July 10, 1997. Published September 1997. Originally
(E 284)
published as E 430 – 71. Last previous edition E 430 – 91.
3.1.3.2 texture, n—the visible surface structure depending
The boldface numbers in parentheses refer to the list of references at the end of
on the size and organization of small constituent parts of a
this method.
Annual Book of ASTM Standards, Vol 06.01. material; typically, the surface structure of a woven fabric.
Annual Book of ASTM Standards, Vol 08.02.
(E 284)
Annual Book of ASTM Standards, Vol 15.09.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
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E 430
3.1.4 Other Terms: appearance. The present method identifies by measurements
3.1.4.1 aperture angle, 2 ,n—angle subtended at a point on important aspects of finishes. Those having identical sets of
k
a specimen by the maximum dimension of the illuminator or numbers normally have the same gloss characteristics. It
receiver, within which the flux in a directional beam is usually requires more than one measurement to identify
contained. properly the glossy appearance of any finish (see Refs 3 and 4).
(1) Discussion—In optics, the symbol k is used for the half
6. Apparatus
angle; hence the recommended symbol here is 2 . (E 284)
k
3.1.4.2 goniophotometer, n—instrument that measures flux 6.1 The apparatus shall be either an abridged goniophotom-
as a function of angles of illumination or observation. (E 284) eter (see Fig. 1 and Fig. 2) or a full goniophotometer (see Fig.
3.2 Terms Specific to This Test Method: 3) that can be set to the specified specular, off-specular, and
3.2.1 Terms Relating to Reflection Haze: aperture angles given in Table 1 and Table 2. The abridged
3.2.1.1 reflection haze, H, n—for a specified specular angle, goniophotometer may have a fixed angle of incidence (for Test
ratio of flux reflected at a specified angle (or angles) from the Method A, 30°; for Test Method B, 20°) and specific fixed
specular direction to the flux similarly reflected at the specular directions of view at which the flux from the specimen is
angle by a specified gloss standard. measured (see Table 1 and Table 2).
(1) Discussion—Modifiers may be used to specify the angles 6.1.1 Geometric Conditions for Test Method A—The direc-
at which the haze is measured (for example, 2° or 5°); whether tion of incidence shall be 30°. The directions of view shall be
H or a logarithmic form is to be stated; or whether H is to be opposite the direction of incidence at 30° for specular reflec-
compensated for the luminance of the specimen by multipli- tance, 29.7 or 30.3° for distinctness of image comparisons, 28
cation by Y /Y , where n denotes the reference white; or
or 32° for narrow-angle haze comparisons, and 25 or 35° for
specimen n
any combination of these. wide-angle haze comparisons. The angular dimensions of the
3.2.2 Terms Relating to Metallic Reflection:
mirror reflected image of the source slit in the plane of
3.2.2.1 metallic brightness, n—freedom of a metal surface measurement and the angular dimensions of the receiver
from diffuse haze or texture.
windows in this plane of measurement shall be as shown in
3.2.3 Terms Relating to Specimen Directionality: Table 1.
3.2.3.1 8with-machine’ direction, n—the axis of a specimen
6.1.2 Geometric Conditions for Test Method B—The direc-
that is parallel to the direction of mill rolling or extrusion, or tion of incidence shall be 20 6 0.1°. The directions of view
other surface-finish texture. shall be opposite the direction of incidence, at 20° for specular
3.2.3.2 8across-machine’ direction, n—the perpendicular to gloss measurement and at 18.1 and 21.9° for narrow-angle
8with-machine’ direction. reflection haze measurement. The angular dimensions of the
3.3 Other appearance terms and definitions in Terminology specularly reflected image of the source slit in the plane of
E 284 are applicable to this test method. measurement and the angular dimensions of the receiver
windows in this plane of measurement shall be as shown in
4. Summary of Test Method
Table 2.
4.1 Several geometrically different measures of light re-
6.1.3 Spectral Conditions—The measurement shall be made
flected by a surface are proposed for use in describing its gloss
with visible light to give results in accordance with the CIE
appearance. In Test Method A, gloss reflectance factor is
spectral luminous efficiency function V (l identical with y¯) in
measured at 30° to the specimen normal using narrow illumi-
the CIE 1931 standard observer and CIE standard illuminant C
nator and receiver aperture angles (0.5° wide maximum).
(see Practice E 308 and Test Method E 1347). If another
Distinctness-of-image gloss is measured at 29.7 or 30.3° or
illuminant A, is used, this shall be specified in the report.
both. Narrow-angle (2°) reflection haze is measured at 28 or
6.1.4 Polarization—The incident flux shall be unpolarized
32° or both, and wide-angle (5°) reflection haze at 25 or 35° or
and the receiver shall be insensitive to the state of polarization
both. The ratio of reflectance factors for 28 or 32° or both,
of the reflected luminous flux.
perpendicular and parallel to the machine direction of the
6.1.5 Clamp—For Test Method A, a rotatable clamp of the
specimen, is computed as a measure of directionality. In
type shown in Fig. 4 may be used for flattening and positioning
Method B, specular gloss is measured at 20° according to Test
the specimen during measurement.
Method D 523, and narrow-angle reflection haze is measured at
7. Standards
18.1 and 21.9°. For additional information on the selection of
geometric conditions, see Guide E 179.
7.1 Three calibrated standards of good planarity shall be
available in either a set of metals or a set of nonmetals,
5. Significance and Use
depending upon which type of surface is measured.
5.1 The gloss of metallic finishes is important commercially
7.2 High-Gloss Standards:
on metals for automotive, architectural, and other uses where
these metals undergo special finishing processes to produce the
appearances desired. It is important for the end-products which
The sole source of supply of the apparatus known to the committee at this time
for Method A is Hunter Associates Laboratory, Reston, VA, and for Method B is
use such finished metals that parts placed together have the
BVK-Gardner USA, Columbia, MD. If you are aware of alternative suppliers,
same glossy appearance.
please provide this information to ASTM Headquarters. Your comments will receive
5.2 It is also important that automotive finishes and other
careful consideration at a meeting of the responsible technical committee, which
high-gloss nonmetallic surfaces possess the desired finished you may attend.
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.
E 430
FIG. 1 Optical Diagram of the Abridged Goniophotometer
7.2.1 High-Gloss Standard for Metals shall be of alumi- protective coating and calibrated for specular gloss and
num, evaporated onto glass and covered with a protective distinctness-of-image gloss.
coating of silicon monoxide, and calibrated for specular gloss
7.3.2 Intermediate Standard for Nonmetals shall be of a
and distinctness-of-image gloss.
ceramic material, such as porcelain enamel on steel, and
7.2.2 High-Gloss Standard for Nonmetals shall be of highly
calibrated for specular gloss and distinctness-of-image gloss.
polished black glass with a refractive index of approximately
7.4 Diffuse Standards shall have a reflectance factor sub-
n 5 1.527, calibrated for specular gloss and reflection haze,
D
stantially constant over the angular range of the instrument.
and assigned a scale value of G 5 89.4 for a specular angle of
s
7.5 Care of Standards—It is essential that the standards be
30° (Test Method A) or G 5 89.2 for a specular angle of 20°
s
kept clean and free of scratches as well as from contact with
(Test Method B).
contaminating materials. The cleaning method specified by the
instrument manufacturer shall be followed and the standards
NOTE 1—To determine the scale value, calculate the first-surface
(Fresnel) reflectance (Test Method D 2457, Section 5.1) for n 5 1.567
should be checked at regular intervals against reference stan-
D
and the specular angle of interest; for 30° it is 5.0436 % and for 20° it is
dards held in reserve.
4.9078 %. Assign this a scale value of 100 (Test Method D 523, Section
7.1). Repeat the calculation for n 5 1.527 and the same specular angle;
p
8. Specimens
the result for 30° is 4.5069 % and for 20°, 4.3769 %. The new scale value
for 30° is 100 3 (4.5069/5.0436) 5 89.4, and for 20°, 100 3 (4.3769/
8.1 Specimens shall be obtained from test samples by
4.9078) 5 89.2. (The latter value is also given in Test Method D 523.)
selecting areas that are plane and representative of each sample
7.3 Intermediate Standards: being tested. Every specimen must be at least 2 ⁄4 in. (70 mm)
7.3.1 Intermediate Standard for Metals shall be of either in the smallest dimension. Specimens may be larger so long as
chromium evaporated onto glass and covered with a protective it is possible to insert them and flatten them properly for
coating of silicon monoxide, or of bright sheet aluminum with measurement.
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.
E 430
full goniophotometer, shown in Fig. 3, identifies the specular
direction by the peak of the goniophotometric curve.
10.3 Rotate the specimen in its own plane to find the
orientation, giving the maximum specular signal. This speci-
men orientation is called the “machine direction” because it
generally coincides with the direction of travel of a sheet or
film material through a processing machine.
10.4 Record the following quantities:
10.4.1 For Test Method A, readings of (a) gloss reflectance
factor (specular gloss), R at 30°; (b) distinctness-of-image
s,30
gloss; (c) 2° reflection haze; H ; and (d) 5° reflection haze, H .
2 5
The quantities in (b), (c), and (d) may be either gloss
reflectance factors or values of H, which are their ratios to the
specular gloss reflectance factor recorded in (a).
10.4.2 For Test Method B, readings of (a)
...
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