ASTM D8163-18(2023)

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: D8163 − 18 (Reapproved 2023)
Standard Test Method for
Determination of Strength of Colorants and Bases for
Architectural, Marine, Maintenance, Commercial, and
Industrial Coatings
This standard is issued under the fixed designation D8163; 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 ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
1.1 This test method covers the determination of strength of
mendations issued by the World Trade Organization Technical
colorant dispersions, colored and white bases, for architectural,
Barriers to Trade (TBT) Committee.
marine, maintenance, commercial, and industrial coatings.
1.2 This test method applies to colorant dispersions and
2. Referenced Documents
colored and white bases regardless of the methods used to
2.1 ASTM Standards:
disperse these materials.
D823 Practices for Producing Films of Uniform Thickness
1.3 The resultant test value is in terms of percent strength in
of Paint, Coatings and Related Products on Test Panels
which a material stronger than standard is implied by values
D1475 Test Method for Density of Liquid Coatings, Inks,
larger than 100 % and weaker than standard is implied by
and Related Products
values less than 100 %. The value of 100 % implies exact
D3964 Practice for Selection of Coating Specimens for
strength conformance to the test method.
Appearance Measurements
1.4 This test method is suitable for the determination of
E284 Terminology of Appearance
strength when tolerances are set about standards that are
E308 Practice for Computing the Colors of Objects by Using
prepared either by weight concentration or volume concentra-
the CIE System
tion.
E1164 Practice for Obtaining Spectrometric Data for Object-
Color Evaluation
1.5 The test result is empirically determined. The user
determines and supplies the standard for strength of the product E1331 Test Method for Reflectance Factor and Color by
under test and the test result is relative to that supplied Spectrophotometry Using Hemispherical Geometry
standard. E1349 Test Method for Reflectance Factor and Color by
Spectrophotometry Using Bidirectional (45°:0° or 0°:45°)
1.6 The values stated in either SI units or inch-pound units
Geometry
are to be regarded separately as standard. The values stated in
each system are not necessarily exact equivalents; therefore, to
3. Terminology
ensure conformance with the standard, each system shall be
used independently of the other, and values from the two
3.1 Definitions: Terms and definitions in Terminology E284
systems shall not be combined.
are applicable to this test method.
1.7 This standard does not purport to address all of the 3.1.1 reflection factor, n—in strength of colorant or base, a
safety concerns, if any, associated with its use. It is the value representative of the fraction of incident radiant energy
responsibility of the user of this standard to establish appro- that is reflected from a surface under conditions specified.
priate safety, health, and environmental practices and deter-
3.1.2 strength, n—of a colorant or base, a value that is
mine the applicability of regulatory limitations prior to use.
quantitatively related to the effective concentration of a test
1.8 This international standard was developed in accor-
colorant or test base relative to the effective concentration of
dance with internationally recognized principles on standard-
the standard or reference for that colorant or base.
This test method is under the jurisdiction of ASTM Committee D01 on Paint
and Related Coatings, Materials, and Applications and is the direct responsibility of
Subcommittee D01.26 on Optical Properties. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved July 1, 2023. Published August 2023. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2017. Last previous edition approved in 2018 as D8163 – 18. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D8163-18R23. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D8163 − 18 (2023)
4. Summary of Test Method usually marked with values that are half these dimensions and
so would be marked 100 μm and 150 μm [4 mils and 6 mils],
4.1 The user supplies a standard base and a standard
respectively. Under some circumstances, drawdown bars with
colorant. A standard sample is prepared from these ingredients
other clearances may be appropriately used.
by a predetermined formula that will achieve a target reflec-
tance. A test sample is made using the same formula by mixing 7.5 Apparatus to hold the drawdown chart in place while the
the material being tested with the appropriate standard material drawdown is made and this may consist of a glass plate or a
depending upon whether the material under test is a colorant or vacuum plate to hold the drawdown flat on a smooth and level
a base. surface.
4.2 The standard sample and the test sample are drawn 7.6 Color Measuring Instrument: a colorimetric spectropho-
down side by side on a black-and-white test chart. tometer meeting the requirements of Practice E1164 having a
spectral range of at least 400 nm to 700 nm at 10 nm intervals
4.3 The drawdown is dried by appropriate means, and the
and having a measuring port ideally 25 mm in size, and
spectral reflectance factor of each standard and sample are
measuring Total:Normal (di:0), sometimes called SPIN or SIN.
measured on a spectrophotometer.
Alternatively, but less desirably, one may utilize a smaller
4.4 A value is selected, or calculated, from among the
measuring aperture and measuring geometry Diffuse:Normal
spectrophotometric reflection functions to represent the relative
(de:0), 45°:Normal (45:0) or (0:45).
reflection factors of each of the two specimens.
8. Reagents and Materials
4.5 These two values are converted by calculation to optical
parameters, K-over-S, where K is the Kubelka-Munk absorp-
8.1 Users are responsible for providing standard strength
tion coefficient and S the Kubelka-Munk scattering coefficient.
white base and standard strength colorants for each colorant or
These values are appropriately put in ratio with each other and
base put under test. These materials will have to be replaced
multiplied by 100 to achieve the test value, relative strength in
when they are depleted, and special care shall be taken that the
percent of the standard value. The ratio assumes that the optical
replacement materials have exact continuity of strength with
parameters are directly, linearly proportional to the relative
the materials they are replacing.
concentration of the dispersed media in the range of concen-
9. Calibration and Standardization
tration used in the test.
9.1 Verify the calibration of the weight per gallon cup at
5. Significance and Use
least once each month in accordance with the instructions for
5.1 The test method results are suitable for use by manu-
doing so in accordance with Test Method D1475.
facturers of colorants and bases for quality control purposes on
9.2 Verify the calibration of the spectrophotometer at least
manufactured product.
once each month in accordance with Practice E1164 in which
5.2 The test method results are suitable for use by purchas-
this process is called standardization and verification.
ers of colorants and bases for incoming quality control or the
determination of money value of colorants and bases. 10. Conditioning
10.1 Assure that all materials have been shaken on a paint
6. Interferences
shaker for at least 2 min on the day on which they will be used.
6.1 Differences between the standard and the test materials
10.2 The viscosity ranges of most materials within the scope
in the following properties may be interpreted by the test
of this test method are such that the vigorous shaking necessary
method as a strength difference and thus comprise an interfer-
to homogenization of the materials causes air to be entrapped
ence with the test: color difference between the standard
in the liquid. As part of the sample conditioning, users shall
specimen and the test specimen in the hue or chroma
employ at least one of the three methods given in Test Method
directions, gloss difference, metamerism, measurement geom-
D1475 for the removal of air from the sample. The methods are
etry differences, hiding differences, and flocculation differ-
centrifugation, vacuum deaeration, and reduction of viscosity
ences.
with solvent, including water if applicable. Only the sample
6.2 The presence of any one or more of these interferences
under current consideration need be deaerated, not the entire
could invalidate the test results.
stored standard material.
7. Apparatus
11. Procedure
7.1 Electronic Scale, with readability of at least 0.001 g and
METHOD A
resolution of at least 0.01 g.
11.1 Colorant Test Method:
7.2 Weight per gallon cup if strength is assessed by volume.
11.1.1 Prepare a wet standard by blending an amount of
7.3 Black-and-white sealed drawdown charts.
standard white base and standard colorant to achieve a reflec-
7.4 Drawdown Bars, capable of applying a coating typically tance at the wavelength of maximum absorption of between
15.25 cm [6 in.] wide. The applicators shall be capable of 35 % and 50 % reflectance with 40 % reflectance considered
applying 200 μm and 300 μm [8 mils and 12 mils] wet film or ideal. Prepare this sample by weight even though the strength
other wet film thickness as appropriate. Bird type bars are value sought may be by volume.
D8163 − 18 (2023)
11.1.2 Prepare a wet sample by blending the identical METHOD B
weight of standard white base as is contained in the wet
11.2 Base Test Method:
standard and an identical weight of test colorant as is contained
11.2.1 Prepare a wet standard by blending an amount of
in the wet standard if the test colorant is to be assessed by
standard white base and standard colorant to achieve a reflec-
weight, otherwise an identical volume as contained in the wet
tance of between 35 % and 50 % reflectance factor with 40 %
standard.
reflectance factor considered ideal. Prepare this sample by
11.1.3 The standard white base used in both samples shall
weight even though the strength value sought is by volume.
be of the same lot and from the same deaerated subsample of
11.2.2 The standard colorant used in both samples shall be
standard white base.
of the same lot and from the same deaerated subsample of
11.1.4 Drawdown the two wet samples side by side on a
standard colorant.
black-and-white sealed drawdown card in accordance with
11.2.3 Prepare a wet sample by blending the identical
Practices D823 Method C for motor-driven blade or Method E
weight of test white base, if the test result is to be assessed by
for hand-held blade. Use a drawdown bar that will achieve a
weight; otherwise, an identical volume, as is contained in the
film thick enough to be opaque when dry. This is usually
wet standard and an identical weight; otherwise, an identical
considered to be met by a contrast ratio of 0.98 or more. Place
volume of standard colorant as is contained in the wet standard.
the test sample on the left half of the card and the standard
The standard colorant used in both samples shall be taken from
sample on the right.
the same lot and the same deaerated subsample of standard
11.1.5 Rub up both samples immediately after the draw-
colorant.
down by rubbing a small circle in the wet paint several times
11.2.4 Follow the procedure of 11.1.4 – 11.1.10 as the
with light pressure from a finger to assess for differences in
balance of the test method procedure is identical for test base
flocculation. Perform this rub up over the black portion of the
to that of the test colorant.
card. Inspect the drawdown for differences in color as a result
of flocculation in either sample. Any visual differences in these METHOD C
properties shall cause a termination of the test at this juncture
11.3 White Colorant Method:
in the test process.
11.3.1 Prepare a wet standard by blending an amount of
11.1.6 Dry the specimen card by air dry overnight, force
standard white colorant and standard black colorant to achieve
drying in a low (approximately 25 °C (77 °F) oven with
a reflectance in neutral base of between 35 and 50 %
moving air), or in a microwave oven.
reflectance factor with 40 % reflectance factor considered
11.1.7 Inspect the drawdown for differences in color in the
ideal. Prepare this sample at an appropriate level of total
hue difference direction, metamerism, or gloss. Any visual
colorant concentration to achieve hiding in the neutral base.
differences in these properties shall cause a termination of the
Prepare this sample by weight even though the strength
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