ASTM D2745-00(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: D2745 − 00 (Reapproved 2023)
Standard Test Method for
Relative Tinting Strength of White Pigments by Reflectance
Measurements
This standard is issued under the fixed designation D2745; 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 3. Summary of Test Method
1.1 This test method describes the procedure for determin-
3.1 Pigment is dispersed in a vehicle and let down with
ing the relative tinting strength of white pigments by reflec- additional vehicle that has been tinted. Dispersion and letdown
tance measurements of black tints.
are accomplished with a mechanical muller. Both the test and
standard pigments are treated identically. Opaque drawdowns
1.2 This test method is applicable only for comparing the
are made of the paint and the Y tristimulus values (green-filter
test pigment with a reference standard of the same type and
reflectance) of the wet films are measured. The relative tinting
grade.
strength of the test pigment is calculated directly from the
NOTE 1—Test Method D332 describes a procedure for visual assess-
reflectance values.
ment of blue-tinted samples.
1.3 The values stated in SI units are to be regarded as the
4. Significance and Use
standard. The values given in parentheses are for information
4.1 Tinting strength is one of the most important properties
only.
of a white pigment. This test method provides a means of
1.4 This standard does not purport to address all of the
testing this property for quality control.
safety concerns, if any, associated with its use. It is the
4.2 This test method is a referee method, and the vehicle for
responsibility of the user of this standard to establish appro-
preparing the dispersion and the black for tinting are suggested,
priate safety, health, and environmental practices and deter-
but others may be used provided both the purchaser and the
mine the applicability of regulatory limitations prior to use.
seller agree to the changes.
1.5 This international standard was developed in accor-
4.3 The results obtained with a muller do not necessarily
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the agree with industrial situations where different dispersing
Development of International Standards, Guides and Recom- conditions exist. However, dispersing with a muller is a fast,
mendations issued by the World Trade Organization Technical relatively inexpensive way of testing tinting strength for
Barriers to Trade (TBT) Committee. routine quality control.
2. Referenced Documents
5. Apparatus and Materials
2.1 ASTM Standards:
5.1 Muller, automatic, equipped with a weight that exerts a
D332 Test Method for Relative Tinting Strength of White
permanent 220 N (50 lbf) and an additional weight exerting a
Pigments by Visual Observation
50 lbf making a total of 445 N (100 lbf). The two glass plates
D2244 Practice for Calculation of Color Tolerances and
shall be kept sharp by removing from the machine and grinding
Color Differences from Instrumentally Measured Color
them face-to-face with No. 303 optical emery or equivalent,
Coordinates
and water.
5.2 Spatula—A flexible spatula having a chromium-plated
or plastic blade 75 mm to 150 mm (3 in. to 6 in.) long, and
This test method is under the jurisdiction of ASTM Committee D01 on Paint
another with a 75 mm (3 in.) tapered blade.
and Related Coatings, Materials, and Applications and is the direct responsibility of
Subcommittee D01.26 on Optical Properties.
5.3 Balances—(1) A balance sensitive to 20 mg and (2) an
Current edition approved July 1, 2023. Published August 2023. Originally
analytical balance sensitive to 0.4 mg.
approved in 1968. Last previous edition approved in 2017 as D2745 – 00 (2017).
DOI: 10.1520/D2745-00R23.
5.4 Vehicle—Because the choice of vehicle may affect
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
results, a solvent-free vehicle (excluding refined or low-bodied
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
linseed oil) should be agreed upon by the purchaser and the
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. seller.
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D2745 − 00 (2023)
5.5 Tinting Black—A lamp black predispersed in a vehicle times more. Prepare a reference standard with each series of
similar in nature to the test vehicle. Tinting black should be test pigments by this same procedure.
agreed upon between the purchaser and the seller.
NOTE 2—An analytical balance is specified for referee-type of testing;
for routine work, weighing to 20 mg has been found satisfactory as an
5.6 Chart—Either gray or white lacquered charts cut to a
alternative procedure. Among the methods of accurately weighing ve-
convenient size.
hicles (either the clear or black letdown vehicles) are these two alterna-
tives: (1) Place a small beaker of vehicle on the weighing pan of the
5.7 Color Measuring Instruments, meeting the requirements
balance. Remove and transfer vehicle employing the spatula ultimately
of Practice D2244.
intended for preparing a paste on the muller. Use the weigh-by-difference
5.8 Film Applicator—50 mm or 75 mm (2 in. or 3 in.) wide
method. (2) Add the vehicle to a tared metal or plastic plate till the correct
weight is reached; transfer to the muller by scraping off the plate with the
with a clearance of 150 μm (6 mils) to produce wet films about
spatula. If the vehicle tends to run, weigh both pigment and vehicle on the
75 μm (3 mils ) thick. This applicator when used as suggested
plate making a crater in the pile of pigment to contain the vehicle.
in the test method will produce an R film.
∞
7.4 Standardize the color measuring instrument for mea-
surement of the green filter reflectance (that is, Y-value) with,
6. Standard
if necessary, a wet-film adapter in place. Adjust the color
6.1 A standard white pigment of the same type as the sample
instrument to the approximate expected reading. Draw down
to be tested, as agreed upon by the purchaser and the seller.
the sample paint on the chart (lacquered side) with the
applicator blade (5.8). Place the film immediat
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