ASTM E97-82(1987)

Method of Test for Directional Reflectance Factor, 45-Deg 0-Deg, of Opaque Specimens by Broad-Band Filter Reflectometry (Withdrawn 1991)

General Information

• Status: Withdrawn
• ICS: 71.040.50 - Physicochemical methods of analysis
• Technical Committee: E12 - Color and Appearance
• Drafting Committee: E12.03 - Geometry

Standards Content (Sample)

IND-STD ASTM E77-82Rô7 VALID NOTICE 1 ô0 W 7777978 OOOLI237 ô I
NOTICE OF
VALIDATION NO'i'ICR 1
VALIDATION
22 June i990 for
ASTM E97-82R87
26 April 1984
ASTM 397-82R87 adopted on 26 April 1984 has been reviewed and determined
to be current.
Custodians:
Military Coordinating activity:
Army - MR
Army - PíR
Air Force - 11
Review activities:
Navy - SH, YD
FSC 8010
DISTRIBUTION STATEMENT A Approved for public release; distribution uniimited.

ASTM E77 82 E 0759510 0047L74 3 W
(i!# E97
two specimens will appear lighter when viewed in daylight at an angle at
6.2 Secondary Standards'-Porcelain-enameled metal
which the observation of highlights is avoided.
plaques, or other materials known to be reasonably perma-
nent in reflectance and uniform over the surface, may be
4.3 blue-light 45-deg, O-deg directional reflectance fac-
calibrated and used as secondary reflectance standards.
tor-the ratio of the light flux from the specimen illuminated
at an angle of 45 deg by CIE standard source C, and viewed
perpendicularly by a receptor whose response is equivalent to
7. Preparation of Test Specimens
the Z-function of the CIE standard observer, to the light flux
7.1 Paint-Unless otherwise speciñed, prepare panels for
from the perfect reflecting diffuser simiiarly illuminated and
the determination of reflectance factor by applying the paint
viewed (see Definitions E 284).
to a suitable flat background with a doctor blade in accord-
NOTE 6-CIE standard sources and functions are defined in Method
ance with Method D823. Use sufficient thickness so that
E 308.
additional coats produce no measurable change in reflec-
tance factor. Allow 72 h for the paint to dry. It is recom-
mended that 60-deg gloss as described in Method D 523 and
5. Apparatus
unusual surface structure be noted.
5.1 The apparatus shall consist of a reflectometer, either
7.2 Porcelain Enamel-Laboratory-prepared specimens,
visual or photoelectric type, having source, filter, receptor,
articles of commerce, or sections cut from articles of
and design characteristics such that it will measure reflec-
commerce may be tested; The area to be tested shall be flat
tance factors accurately to within 1 .O % of full-scale reading.
and reasonably free of surface defects. Laboratory specimens
The apparatus shall have the following characteristics:
shall be at least 60 by 90 mm (2V2 by 3% in.) in size;
5.1.1 Spectral Characteristics:
however, specimens 100 by 100 mm (4 by 4 in.) are
5.1.1.1 For Measurement of Daylight Luminous Reflec-
preferred.
tance Factor-The spectral energy distribution of the illumi-
nator and the spectral sensitivity of the receptor, in combi-
NOTE 9-The method of preparation of the specimen, such as weight
nation, shall provide the equivalent of illumination by CIE
of application or firing treatment, may affect the reflectance factor but is
standard source C and observation by the luminosity (y)
not a part of this test method; however, each manufacturer should
investigate the effect of such variables on the reflectance factor of his
function of the 193 1 CIE standard observer.
products (see Method C 347).
NOTE 7-Spectral characteristics based on CIE standard illuminant
DS5 or any other CIE daylight standard illuminant, or on the 7 function
7.3 Paper-Sample in accordance with Method D 585.
of the CE 1964 supplementary standard observer (which is not the
Handle the test specimen carefully to avoid soiling, and take
luminosity function) may be used as an alternative.
care not to touch the areas to be tested. The test specimen
5.1.1.2 For Measurement of Blue-Light Reflectance Fac-
shall consist of a pad of sheets sufficiently thick that doubling
tor-The product of spectral energy of source, spectral
the number of sheets causes no measurable change in
transmission of filters, and spectral response of receptor shall
reflectance factor,
be equivalent to the product of the 2-function of the CIE
7.4 Other Materials-Prepare test specimens of materials
standard observer multiplied by the energy distribution of
other than those listed in 7.2 and 7.3 in accordance with
CIE standard source C.
accepted practice, and record the method of preparation in
5.1.2 Geometric Characteristics-Illumination shall be
the report.
within 4 deg of, and centered about, a single direction of 45
deg from the perpendicular to the test surface. It shall be NOTE 10-All high-reflectance dimisely reflecting materials are
somewhat translucent since most of their reflectance is due to internal
effectively aonpolarized. Viewing shall be within 15 deg of,
scattering. Roughly 95 % of the incident light is transmitted through the
and centered about, the perpendicular.
surface, and partially absorbed. What is not absorbed is multiply
NOTE 8-Any instrument that meets these apparatus specifications scattered back to the surface, at a point dflerent from the point of
may be used. Instruments should also meet the precision requirements
incidence, where it is retransmitted as reflected light. The maximum
prescribed in Section 11. In general, commercial instruments do not
distance between the points of incidence and exitance is primarily a
conform exactly to the apparatus requirements. The suitability of a function of the extinction coefficient of the material. For materials such
given instrument depends in large measure on the spectral selectivity of
as most white paints and porcelain enamels, the extinction coefficient is
the specimens being measured, and on the availability of standards of large, and the maximum distance of travel is small, and errors due to
similar reflectance and spectral character? this internal travel may be small enough to be neglected. Other
high-reflectance materials, such as opal glass and white plastics, may
have smaller extinction coefficients, and the maximum distance of
6. Standards
internal travel may be large enough (several miiiimetres is not un-
common) that significant light losses can occur unless the reflectometer
6.1 Primary Standard-The primary standard for reflec-
has been designed to eliminate such losses. The maximum errors occur
tance is the perfect reflecting diffuser as described in Defini-
in measurements of reflection factor when comparing sample and
tions E 284. It is assigned a value of 100 for the conditions of
standard of markedly different extinction coefficients. See NBS Tech-
nical Note 59
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