ASTM E259-98(2003)

Standard Practice for Preparation of Pressed Powder White Reflectance Factor Transfer Standards for Hemispherical and Bi-Directional Geometries

SCOPE
1.1 This practice covers procedures for preparing pressed powder transfer standards. These standards can be used in the near-ultraviolet, visible and near-infrared region of the electromagnetic spectrum. Procedures for calibrating the reflectance factor of materials on an absolute basis are contained in CIE Publication No. 44. Pressed powder standards are used as transfer standards for such calibrations because they have a high reflectance factor that is nearly constant with wavelength, and because the geometric distribution of reflected flux resembles that from the perfect reflecting diffuser.
1.2 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only.
1.3 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

• Status: Historical
• Publication Date: 09-Jul-2003
• ICS: 17.180.20 - Colours and measurement of light
• Technical Committee: E12 - Color and Appearance
• Drafting Committee: E12.02 - Spectrophotometry and Colorimetry

Relations

• Replaces: ASTM E259-98 - Standard Practice for Preparation of Pressed Powder White Reflectance Factor Transfer Standards for Hemispherical Geometry and Bi-Directional Geometries
• Effective Date: 10-Jul-2003
• Replaced By: ASTM E259-06 - Standard Practice for Preparation of Pressed Powder White Reflectance Factor Transfer Standards for Hemispherical and Bi-Directional Geometries
• Effective Date: 01-Sep-2006
• Referred By: ASTM C609-20 - Standard Test Method for Measurement of Light Reflectance Value and Small Color Differences Between Pieces of Ceramic Tile
• Effective Date: 10-Jul-2003
• Referred By: ASTM D1003-21 - Standard Test Method for Haze and Luminous Transmittance of Transparent Plastics
• Effective Date: 10-Jul-2003
• Referred By: ASTM E491-73(2020) - Standard Practice for Solar Simulation for Thermal Balance Testing of Spacecraft
• Effective Date: 10-Jul-2003
• Referred By: ASTM E805-22 - Standard Practice for Identification of Instrumental Methods of Color or Color-Difference Measurement of Materials
• Effective Date: 10-Jul-2003
• Referred By: ASTM E1791-96(2021) - Standard Practice for Transfer Standards for Reflectance Factor for Near-Infrared Instruments Using Hemispherical Geometry
• Effective Date: 10-Jul-2003
• Referred By: ASTM D3210-95(2023) - Standard Test Method for Comparing Colors of Films from Water-Emulsion Floor Polishes
• Effective Date: 10-Jul-2003
• Referred By: ASTM E1164-12(2023)e1 - Standard Practice for Obtaining Spectrometric Data for Object-Color Evaluation
• Effective Date: 10-Jul-2003
• Referred By: ASTM E424-71(2023) - Standard Test Methods for Solar Energy Transmittance and Reflectance (Terrestrial) of Sheet Materials
• Effective Date: 10-Jul-2003

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: E 259 – 98 (Reapproved 2003)
Standard Practice for
Preparation of Pressed Powder White Reflectance Factor
Transfer Standards for Hemispherical and Bi-Directional
Geometries
This standard is issued under the fixed designation E259; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
The internationally accepted standard of reflectance is the perfect reflecting diffuser. This ideal
reflecting surface reflects 100% of the incident radiant power such that the radiance is the same for
all directions within the hemisphere above the surface. No physical realization of this standard exists.
Optical properties of standards prepared from pressed plaques of magnesium carbonate (MgCO ),
barium sulfate (BaSO ), or polytetrafluoroethylene (PTFE) can approximate an ideal standard. For
further information see CIE Publication No. 46 (1). The principal use of a white reflectance factor
standard is to transfer an absolute scale of reflectance to a more durable material or from one
instrument to another. In theory, it should be easy to do this transfer from first principles. In practice,
one is likely to need values for parameters that are unknown, proprietary, or require a high level of
skill. Some, but not all, of those parameters are discussed in this practice.
1. Scope 2. Referenced Documents
1.1 This practice covers procedures for preparing pressed 2.1 ASTM Standards:
powder transfer standards. These standards can be used in the E284 Terminology of Appearance
near-ultraviolet, visible and near-infrared region of the electro-
3. Terminology
magnetic spectrum. Procedures for calibrating the reflectance
3.1 Terms and definitions in Terminology E284 are appli-
factor of materials on an absolute basis are contained in CIE
Publication No. 44 (2). Pressed powder standards are used as cable to this practice.
3.2 Definitions—The following definitions are particularly
transfer standards for such calibrations because they have a
high reflectance factor that is nearly constant with wavelength, important to this practice:
3.2.1 perfect reflecting diffuser—idealreflectingsurfacethat
and because the geometric distribution of reflected flux re-
sembles that from the perfect reflecting diffuser. neither absorbs nor transmits light, but reflects diffusely, with
the radiance of the reflecting surface being the same for all
1.2 The values stated in SI units are to be regarded as the
standard. The values in parentheses are for information only. reflecting angles, regardless of the angular distribution of the
incident light. (1990)
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 3.2.2 reflectance, r, n—ratio of the reflected radiant or
responsibility of the user of this standard to establish appro- luminous flux to the incident flux in the given conditions.
A
[CIE]
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. 3.2.3 Theterm reflectanceisoftenusedinageneralsenseor
as an abbreviation for reflectance factor. Such usage may be
assumed unless the above definition is specifically required by
This practice is under the jurisdiction ofASTM Committee E12 on Color and
the context. (1989b)
Appearance and is the direct responsibility of Subcommittee E12.02 on Spectro-
3.2.4 reflectance factor, R, n—ratio of the flux reflected
photometry and Colorimetry.
from the specimen to the flux reflected from the perfect
Current edition approved July 10, 2003. Published July 2003. Originally
approved in 1965. Last previous edition approved in 1998 as E259–98.
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
this practice. Annual Book of ASTM Standards, Vol 06.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E 259 – 98 (2003)
reflecting diffuser under the same geometric and spectral Fig. 1. The optical surface of the plaque should be pressed
B
conditions of measurement. [CIE] (1988) against a surface of ground glass or poly(methyl methacrylate)
to provide a matte finish on the pressed plaque. Powder
4. Summary of Practice
receptaclesshouldbeatleast5mmdeepforBaSO andatleast
10 mm deep for PTFE.
4.1 Procedures are given for the preparation of white
reference standards of diffuse reflectance factor and diffuse
7. Reagents and Materials
radiancefactor.Therecommendedmaterialsarewhitepowders
7.1 Barium Sulfate—the barium sulfate should be of the
that are pressed into plaques. These plaques provide close
highest purity. It should be specially refined for optical and
approximations to the optical properties of the perfect reflect-
spectroscopic use (3).
ing diffuser, and may be used to transfer a scale of absolute
7.2 Polytetrafluoroethylene—the PTFE (4) should also be
reflectance to another material or to an instrument.
specially refined for optical and spectroscopic use but some
5. Significance and Use commercial grades have been found to be acceptable substi-
tutes. (5) There is currently no commercial source for small
5.1 All commercial reflectometers measure relative reflec-
quantities of optical grade PTFE powder. Large quantities
tance.Theinstrumentreadingisthereflectancefactor,theratio
(drums) of commercial grade PTFE can be obtained from
of the light reflected by a reference specimen to that reflected
manufacturers.
by a test specimen. That ratio is dependent on specific
instrument parameters.
8. Procedure
5.2 National standardizing laboratories and some research
8.1 Store all powdered reflectance standards in tightly
laboratories measure reflectance on instruments calibrated
capped glass containers. If the powder is purchased in plastic
from basic principles, thereby establishing a scale of absolute
containers, transfer it to a glass container as soon as possible.
reflectance as described in CIE Publication No. 44 (2). These
Before using the powder, place it in a glass blender equipped
measurementsaresufficientlydifficultthattheyareusuallyleft
with stainless-steel or PTFE-coated blades and pulverize to a
to laboratories that specialize in them.
uniform consistency. Transfer the quantity of powder to be
5.3 Astandard that has been measured on an absolute scale
used with stainless steel or PTFE-coated spoons. Perform the
could be used to transfer that scale to a reflectometer. While
whole operation in a draft-free location, away from sources of
suchproceduresexist,theconstraintsplacedonthemechanical
small particulate contamination, filters, sweaters, windows,
properties restrict the suitability of some optical properties,
ovens, etc. Perform all measurements (weight, height, width,
especiallythosepropertiesrelatedtothegeometricdistribution
depth, volume, area, etc.) with adequate precision to ensure
of the reflected light. Thus, reflectance factor standards which
that the final density is within 5% of the specified value. The
are sufficiently rugged and able to be cleaned, depart consid-
most reproducible standards are made by pressing the powder
erablyfromtheperfectdiffuserinthegeometricdistributionof
toaspecificdensity.Thus,determinethemassofthepowderto
reflected radiance.
be used from the volume of the receptacle.
5.4 The geometric distribution of reflected radiance from a
8.2 Barium Sulfate—Press BaSO to a density of 2000
pressed powder plaque is sufficiently diffuse to provide a 4
3 3
kg/m (2.0 gm/cm ) and a thickness of at least 5 mm. Press
dependable calibration of a directional-hemispherical reflecto-
several specimens in succession. Select matched pairs to be
meter. Although pressed powder standards are subject to
representativeofthecontentsofthebottleofpowder.Keepthe
contamination and breakage, the directional-hemispherical re-
pressed plaques in a covered desiccator when not in use. Some
flectancefactorofpressedpowderstandardscanbesufficiently
suppliers of BaSO provide calibration values with each bottle
reproduciblefromspecimentospecimenmadefromagivenlot 4
ofpowder,othersuppliersprovideonly3or4qualityreference
of powder, so as to allow one to assign absolute reflectance
checks and a reference to published values of reference
factor values to all the powder in a lot.
5.5 Thispracticedescribeshowtopreparewhitereflectance
factor standards from a powder in a manner that allows a
standardizing laboratory to assign the absolute scale of reflec-
tance to the plaque.
6. Apparatus
6.1 The basic apparatus for producing a pressed powder
standard includes a powder press, powder containers and a
balance. There are presently two commercial suppliers of
powderpresses. Thepressandreceptaclescanalsobemadein
a local machine sh
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