ASTM D1729-96
(Practice)Standard Practice for Visual Appraisal of Colors and Color Differences of Diffusely-Illuminated Opaque Materials
Standard Practice for Visual Appraisal of Colors and Color Differences of Diffusely-Illuminated Opaque Materials
SCOPE
1.1 This practice specifies the equipment and procedures for visual appraisal of the colors and color differences of opaque materials that are diffusely illuminated. These specification are of critical importance in color matching. This practice requires judgments by observers with normal color vision.
1.2 Critical visual appraisal of colors and color differences of materials such as metallic and pearlescent paints requires illumination that is nearly a geometric simulation of sunlight, because such directional illumination permits observation of the glitter and goniochromatism that characterize such materials. Such viewing conditions are beyond the scope of this practice.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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 the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
Designation: D 1729 – 96
Standard Practice for
Visual Appraisal of Colors and Color Differences of
Diffusely-Illuminated Opaque Materials
This standard is issued under the fixed designation D 1729; 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.
This standard has been approved for use by agencies of the Department of Defense to replace Method 4249.1 of Federal Test Method
Standard No 141. Consult the DoD Index of Specifications and Standards for the specific year of issue which has been adopted by the
Department of Defense.
INTRODUCTION
The colors of materials depend on the geometric and spectral nature of the illuminating and viewing
conditions. This practice specifies standard conditions for appraising the colors and color differences
of opaque specimens that are diffusely illuminated. Daylight, the natural illuminant, is usually of
primary interest, but natural daylight is highly variable and is not available at night or in interior
rooms, so simulated daylight is generally used. Colors may match under a light source with one
spectral power distribution, but not under another, so the match is usually confirmed under another
very different source. An incandescent lamp of low correlated color temperature has long been used
to detect mismatches likely to appear under yellower phases of daylight or incandescent light.
Industrial color matchers often verify the match with the kind of light likely to be found where the
product is sold or used. Judgments must be made by observers with normal color vision. Even so, there
may be substantial individual differences in judgments.
1. Scope 2. Referenced Documents
1.1 This practice specifies the equipment and procedures for 2.1 ASTM Standards:
visual appraisal of the colors and color differences of opaque D 523 Test Method for Specular Gloss
materials that are diffusely illuminated. These specification are D 1535 Practice for Specifying Color by the Munsell Sys-
of critical importance in color matching. This practice requires tem
judgments by observers with normal color vision. D 4086 Practice for Visual Evaluation of Metamerism
1.2 Critical visual appraisal of colors and color differences D 5531 Guide for the Preparation, Maintenance, and Distri-
of materials such as metallic and pearlescent paints requires bution of Physical Product Standards for Color and Geo-
illumination that is nearly a geometric simulation of sunlight, metric Appearance of Coatings
because such directional illumination permits observation of E 284 Terminology of Appearance
the glitter and goniochromatism that characterize such materi- E 308 Practice for Computing the Colors of Objects by
als. Such viewing conditions are beyond the scope of this Using the CIE System
practice. E 1164 Practice for Obtaining Spectrophotometric Data for
1.3 The values stated in SI units are to be regarded as the Object-Color Evaluation
standard. The values given in parentheses are for information E 1499 Guide to the Selection, Evaluation, and Training of
only. Observers
1.4 This standard does not purport to address all of the 2.2 ISO/CIE Standard:
safety concerns, if any, associated with its use. It is the 10526 CIE Standard Colorimetric Illuminants (1991)
responsibility of the user of this standard to establish appro-
3. Terminology
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. 3.1 For definitions of appearance terms used in this practice,
refer to Terminology E 284.
This practice is under the jurisdiction of ASTM Committee E-12 on Appear-
ance and is the direct responsibility of Subcommittee E-12.11 on Visual Methods. Annual Book of ASTM Standards, Vol 06.01.
Current edition approved Nov. 10, 1996. Published March 1997. Originally Available from CIE/USA Publications, c/o Mr. Thomas M. Lemmons, TLA
published as D 1729 – 60 T. Last previous edition D 1729 – 89. Lighting Consultants, Inc., 7 Pond Street, Salem, MA 01870.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
D1729–96
4. Significance and Use method specified in the latest revision of CIE Publication 51
(under revision in 1996). For critical appraisal of colors and
4.1 Although color measuring instruments are widely used,
color differences, the category determined by that method shall
color matches are usually checked visually. The standardiza-
be BC(CIELAB) or better. This rating ensures that the source
tion of visual examination has greatly improved the uniformity
provides ultraviolet and visible power in the right proportions
of products and the accuracy of color matches.
to make both nonfluorescent and fluorescent materials look
4.2 The use of this practice is essential for critical color
very nearly the way they would in the corresponding phase of
matching but is also recommended for any color appraisal,
natural daylight. Users of this practice should be aware of the
such as the choice or approval of a color. This practice is
fact that neither correlated color temperature nor chromaticity
widely used in industry to choose colors, exhibit colors
alone qualifies simulated daylight for this purpose.
reproducibly, inspect incoming materials, monitor color pro-
6.1.1.2 Incandescent illumination shall have the spectral
ducing processes, and inspect finished goods. Visual appraisal
quality of the light from an incandescent lamp commonly used
is particularly important when the product inspected is not of
for home and business lighting, approximately simulating CIE
the same material as the color standard to which it is compared.
Illuminant A, specified in Practice E 308 and ISO/CIE 10526.
4.2.1 Observers—This practice is based on the fundamental
6.1.1.3 Incandescent illumination of low correlated color
assumption that the observer has normal color vision and is
temperature shall have spectral quality similar to that of a
trained and experienced in observing and classifying color
Planckian radiator having a color temperature of 2300 K. This
differences. The significance of the results depends on that
light is commonly produced by incandescent lamps operated at
being so. The selection, evaluation, and training of observers
half their rated voltage.
are treated in Guide E 1499.
6.1.1.4 Fluorescent lamps are often provided. Those most
4.2.2 Illumination—Simulated average daylight is recom-
often used are of the type known as “cool white” approxi-
mended by the International Commission on Illumination
mately simulated by CIE Illuminant F2, and the type known as
(CIE), but a slightly bluer simulated north-sky daylight came
“three-band” approximately simulated by CIE Illuminant F11.
into widespread use in North America, because it provides a
The spectra of these illuminants are specified in Practice E 308
slightly greater distinction between very pale yellow and white,
and ISO/CIE 10526.
a distinction of great commercial importance.
6.1.1.5 One or several of these kinds of illumination, or
other kinds, as specified, may be provided in a luminaire or
5. Observers
viewing booth. Provision must be made for selecting any one
5.1 The validity of the results obtained by this practice
of the sources independently.
depends on visual judgments by an observer or observers with
6.1.2 Photometric Conditions—For critical evaluation of
normal color vision. Even among normal observers, there may
color differences of materials of medium lightness, the illumi-
be substantial individual variations. Color specifications de-
nation at the center of the viewed area shall be 1080 to 1340 lx
pendent on this practice may require averaging the results
(100 to 125 fc). For general evaluation of materials of medium
obtained by a specified number of observers. The nature of an
lightness, the illumination shall be between 810 and 1880 lx
observer’s color vision can be ascertained by visual tests.
(75 and 175 fc). In either case, for viewing very light materials,
Observers should be tested periodically, because an individu-
the illumination may be as low as 540 lx (50 fc), and for
al’s color vision can change (see Guide E 1499).
viewing very dark materials it may be as high as 2150 lx (200
fc). This higher level of illumination is usually obtained by
6. Apparatus
holding the specimens nearer the source.
6.1 The apparatus shall consist of luminaires, specimen
6.1.3 Geometric Conditions—The illumination shall be pro-
table, surround, and ambient field having the following spec-
vided by an extended-area source located above the specimens
tral, photometric, and geometric characteristics:
and shall be sufficiently directional to reveal the texture of
6.1.1 Spectral Power Distribution—The spectral power dis-
specimens. The illuminance shall be uniform
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