Standard Test Method for Reflectance Factor and Color by Spectrophotometry Using Bidirectional (45°:0° or 0°:45°) Geometry

SIGNIFICANCE AND USE
5.1 The most direct and accessible methods for obtaining the color coordinates of object colors are by instrumental measurement using spectrophotometers or spectrocolorimeters with either hemispherical or bidirectional optical measuring systems. This test method provides procedures for such measurement by spectrophotometry using a bidirectional (0:45 or 45:0) optical measuring system. The method for color and color difference measurement using filter colorimeters is contained in Test Method E1347.  
5.2 This test method is especially suitable for measurement of the following types of specimens for the indicated uses (see also Guide E179 and Practice E805):  
5.2.1 Object-color specimens of any gloss level for color assessment.  
5.2.2 Object-color specimens with physically flat, smooth surfaces from which to obtain data for use in computer colorant formulation.  
5.2.3 Retroreflective specimens.
Note 1: To ensure inter-instrument agreement in the measurement of specimens with intermediate gloss, for formulation, or of retroreflective specimens, significantly tighter tolerances than those given in Practice E1164, Influx and Efflux Conditions, 45°:Normal (45:0) and Normal:45° (0:45) Reflectance Factor section, may be required for the instrument angles of illumination and viewing. Information on the required tolerances is being developed.  
5.3 This test method is not recommended for measurement of specimens with bare metal surfaces for color assessment, for which the use of hemispherical measurement geometry, as with an integrating-sphere type instrument, is preferable (see Guide E179).
SCOPE
1.1 This test method covers the instrumental measurement of the reflection properties and color of object-color specimens by use of a spectrophotometer or spectrocolorimeter with a bidirectional optical measuring system, such as annular, circumferential, or uniplanar 45:0 or 0:45 geometry.  
1.2 This test method is generally suitable for any non-fluorescent, flat object-color specimen. It is especially recommended for measuring retroreflective specimens and specimens of intermediate gloss.  
1.3 Procedures required for the measurement of fluorescent object color are given in Practice E991 and Practice E2153.  
1.4 Procedures required for the measurement of color using filter colorimeters are contained in Test Method E1347 and this standard does not address those instruments.  
1.5 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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ASTM E1349-06(2022) - Standard Test Method for Reflectance Factor and Color by Spectrophotometry Using Bidirectional (45°:0° or 0°:45°) Geometry
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E1349 −06 (Reapproved 2022)
Standard Test Method for
Reflectance Factor and Color by Spectrophotometry Using
Bidirectional (45°:0° or 0°:45°) Geometry
This standard is issued under the fixed designation E1349; 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 E179 Guide for Selection of Geometric Conditions for
Measurement of Reflection and Transmission Properties
1.1 This test method covers the instrumental measurement
of Materials
of the reflection properties and color of object-color specimens
E284 Terminology of Appearance
by use of a spectrophotometer or spectrocolorimeter with a
E308 PracticeforComputingtheColorsofObjectsbyUsing
bidirectional optical measuring system, such as annular,
the CIE System
circumferential, or uniplanar 45:0 or 0:45 geometry.
E694 Specification for Laboratory Glass Volumetric Appa-
1.2 This test method is generally suitable for any non-
ratus
fluorescent, flat object-color specimen. It is especially recom-
E805 Practice for Identification of Instrumental Methods of
mendedformeasuringretroreflectivespecimensandspecimens
Color or Color-Difference Measurement of Materials
of intermediate gloss.
E991 Practice for Color Measurement of Fluorescent Speci-
mens Using the One-Monochromator Method
1.3 Procedures required for the measurement of fluorescent
object color are given in Practice E991 and Practice E2153. E1164 PracticeforObtainingSpectrometricDataforObject-
Color Evaluation
1.4 Procedures required for the measurement of color using
E1345 Practice for Reducing the Effect of Variability of
filter colorimeters are contained inTest Method E1347 and this
Color Measurement by Use of Multiple Measurements
standard does not address those instruments.
E1347 Test Method for Color and Color-Difference Mea-
1.5 This standard does not purport to address all of the
surement by Tristimulus Colorimetry
safety concerns, if any, associated with its use. It is the
E1767 Practice for Specifying the Geometries of Observa-
responsibility of the user of this standard to establish appro-
tion and Measurement to Characterize the Appearance of
priate safety, health, and environmental practices and deter-
Materials
mine the applicability of regulatory limitations prior to use.
E2153 Practice for Obtaining Bispectral Photometric Data
1.6 This international standard was developed in accor-
for Evaluation of Fluorescent Color
dance with internationally recognized principles on standard-
E2214 Practice for Specifying and Verifying the Perfor-
ization established in the Decision on Principles for the
mance of Color-Measuring Instruments
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
3. Terminology
Barriers to Trade (TBT) Committee.
3.1 Definitions:
2. Referenced Documents 3.1.1 ThedefinitionscontainedinGuideE179,Terminology
2 E284, Practice E1164, Practice E1767, and Practice E2214 are
2.1 ASTM Standards:
applicable to this test method.
D2244 Practice for Calculation of Color Tolerances and
Color Differences from Instrumentally Measured Color
4. Summary of Test Method
Coordinates
4.1 Thistestmethodprovidesaprocedureformeasuringthe
reflectance factors of reflecting object-color specimens by
This test method is under the jurisdiction of ASTM Committee E12 on Color
usingaspectrophotometerorspectrocolorimeterequippedwith
and Appearance and is the direct responsibility of Subcommittee E12.02 on
Spectrophotometry and Colorimetry.
a bidirectional optical measuring system.
Current edition approved Oct. 1, 2022. Published November 2022. Originally
4.2 When the specimens exhibit directionality, and an in-
approved in 1990. Last previous edition approved in 2018 as E1349 – 06 (2018).
DOI: 10.1520/E1349-06R22.
strument with uniplanar geometry is used, information on
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
directionality may be obtained by measuring the specimens at
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
more than one rotation angle, typically at two angles 90° apart
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. as described in Practice E1345. When such information is not
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1349 − 06 (2022)
required, these measurements may be averaged, or an instru- 6.2.1 White Standard of Bidirectional Reflectance Factor
ment with annular or circumferential geometry may be used. (mandatory)—(A standard of hemispherical reflectance factor
However, even with annular or circumferential influx or efflux is not suitable and should not be used.)
optics, some of the variability induced by specimen — optical 6.2.2 Standardization Materials, (1) for setting or verifying
system interactions may remain and the application of the zero on the reflectance scale; (2) for verifying the wavelength
methods in Practice E1345 may help to further reduce those scale; and (3) for evaluating stray light (optional).
measurement errors. 6.2.3 Verification Standards (recommended)—(See Practice
E1164, Standardization and Material Standards, System Veri-
4.3 This test method includes procedures for standardizing
fication section.)
the instrument or verifying its standardization, and for select-
ing specimens suitable for precision measurement.
NOTE 2—If retroreflective specimens are to be measured, the set of
verification standards should include appropriate retroreflective product
4.4 Most modern spectrometers have the capacity to com-
standards.
pute the color coordinates of the specimen immediately fol-
lowing the measurement. When this is the case, the user must
7. Test Specimen
preselect the color system, observer, and illuminant (see
7.1 For highest precision and accuracy, select specimens
Practice E308, Procedure section).
with the following properties:
7.1.1 High material uniformity and freedom from blemishes
5. Significance and Use
in the area to be measured.
5.1 The most direct and accessible methods for obtaining
7.1.2 Opaquespecimensthathaveatleastoneplanesurface;
the color coordinates of object colors are by instrumental
translucent specimens that have two essentially plane and
measurement using spectrophotometers or spectrocolorimeters
parallel surfaces and that have a standard thickness, when one
with either hemispherical or bidirectional optical measuring
is specified (see Practice E1164, Test Specimens section).
systems. This test method provides procedures for such mea-
7.2 If specimens exhibit directionality, use appropriate pro-
surement by spectrophotometry using a bidirectional (0:45 or
cedures (see 9.7) and calculations (see 10.1.1, Practice E1164,
45:0) optical measuring system. The method for color and
Test Specimens section, and Practice E1345).
color difference measurement using filter colorimeters is con-
tained in Test Method E1347.
8. Standardization and Verification
5.2 This test method is especially suitable for measurement
8.1 Standardize or verify the calibration of the following:
of the following types of specimens for the indicated uses (see
(See Practice E1164, Standardization and Material Standards
also Guide E179 and Practice E805):
section.)
5.2.1 Object-color specimens of any gloss level for color
8.1.1 Zero setting of the reflectance scale (mandatory),
assessment.
8.1.2 Wavelength scale (recommended), and
5.2.2 Object-color specimens with physically flat, smooth
8.1.3 Stray-light level (optional).
surfacesfromwhichtoobtaindataforuseincomputercolorant
8.2 Standardize the full-scale value of the reflectance scale
formulation.
of the instrument by use of the white reflectance standard
5.2.3 Retroreflective specimens.
(mandatory). Follow the instrument manufacturer’s instruc-
NOTE 1—To ensure inter-instrument agreement in the measurement of
tions.
specimens with intermediate gloss, for formulation, or of retroreflective
specimens, significantly tighter tolerances than those given in Practice
8.3 Verifytheaccuracyoftheinstrumentaldatabymeasure-
E1164, Influx and Efflux Conditions, 45°:Normal (45:0) and Normal:45°
ment of a series of verification standards (recommended). (See
(0:45) Reflectance Factor section, may be required for the instrument
Practice E1164, Standardization and Material Standards sec-
anglesofilluminationandviewing.Informationontherequiredtolerances
tion.)
is being developed.
5.3 This test method is not recommended for measurement
9. Procedure
ofspecimenswithbaremetalsurfacesforcolorassessment,for
9.1 When required, select the color scales, observer, and
whichtheuseofhemisphericalmeasurementgeometry,aswith
illuminant for the computation of color coordinates (see
an integrating-sphere type instrument, is preferable (see Guide
Practice E308, Procedure
...

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