ASTM D387-00
(Test Method)Standard Test Method for Color and Strength of Chromatic Pigments with a Mechanical Muller
Standard Test Method for Color and Strength of Chromatic Pigments with a Mechanical Muller
SIGNIFICANCE AND USE
Color and tinting strength are the most important properties of a color pigment. This test method provides a means of testing these properties for quality control.
This test method is intended as a referee method so that such matters as the vehicle for preparing the dispersions and the white for making tints have been suggested. However, other vehicles and whites may be suitable for quality control purposes, and changes in this test method are allowed by agreement between the parties to a test.
It is assumed that the most exact comparison of mass color and tinting strength occurs when the pigment is completely dispersed. By following the procedure described in Annex A1, the conditions for achieving the maximum practical degree of dispersion with a mechanical muller may be determined. Color and strength tests should be carried out under these conditions.
The results obtained with a mechanical muller do not necessarily correlate directly with an industrial situation where different dispersing conditions exist. However, dispersion with a mechanical muller is a quick and inexpensive way of testing the color and strength of a pigment for routine quality control.
SCOPE
1.1 This test method is intended to be used to compare the color and strength of a pigment under test with a reference standard of the same type and grade.
1.2 This test method does not apply to white pigments. Note 1-Test Method D3022 is similar to this test method, but it utilizes a miniature sandmill rather than a mechanical muller, to disperse the color pigment. Note 2-Test Method D332 and Test Method D2745 are similar to this test method, but they are intended for use with white pigments, rather than color pigments.
1.3 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems 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.> Specific hazard statements are given in Section 7.
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Designation:D387–00
Standard Test Method for
Color and Strength of Chromatic Pigments with a
Mechanical Muller
This standard is issued under the fixed designation D 387; 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 (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope D 3964 Practice for Selection of Coating Specimens for
Appearance Measurements
1.1 This test method is intended to be used to compare the
D 4838 Test Method for Determining the Relative Tinting
color and strength of a pigment under test with a reference
Strength of Chromatic Paints
standard of the same type and grade.
E 284 Terminology of Appearance
1.2 This test method does not apply to white pigments.
NOTE 1—Test Method D 3022 is similar to this test method, but it 3. Terminology
utilizes a miniature sandmill rather than a mechanical muller, to disperse
3.1 Definitions of appearance terms used in this test method
the chromatic pigment.
may be found in Terminology E 284.
NOTE 2—Test Method D 332 and Test Method D 2745 are similar to
this test method, but they are intended for use with white pigments, rather
4. Summary of Test Method
than cohromatic pigments.
4.1 Pigments are dispersed in a suitable vehicle with a
1.3 The values stated in SI units are the preferred unit of
mechanical muller. Test and standard pigments are treated
measurement. The values given in parentheses are for infor-
identically. Opaque drawdowns are made from the dispersions
mation only.
and compared, either visually or instrumentally, for color and
1.4 This standard does not purport to address all of the
strength differences.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
5. Significance and Use
priate safety and health practices and determine the applica-
5.1 Color and tinting strength are the most important prop-
bility of regulatory limitations prior to use. Specific hazard
erties of a color pigment.This test method provides a means of
statements are given in Section 8.
testing these properties for quality control.
5.2 This test method is intended as a referee method so that
2. Referenced Documents
such matters as the vehicle for preparing the dispersions and
2.1 ASTM Standards:
the white for making tints have been suggested. However,
D 332 Test Method for Relative Tinting Strength of White
other vehicles and whites may be suitable for quality control
Pigments by Visual Observation
purposes, and changes in this test method are allowed by
D 1729 Practice for Visual Evaluation of Color Differences
agreement between the parties to a test.
of Opaque Materials
5.3 It is assumed that the most exact comparison of mass
D 2244 Test Method for Calculation of Color Differences
color and tinting strength occurs when the pigment is com-
from Instrumentally Measured Color Coordinates
pletely dispersed. By following the procedure described in
D 2745 Test Method for Relative Tinting Strength of White
AnnexA1, the conditions for achieving the maximum practical
Pigments by Reflective Measurements
degree of dispersion with a mechanical muller may be deter-
D 3022 Test Method for Color and Strength of Color
mined. Color and strength tests should be carried out under
Pigments by Use of a Miniature Sandmill
these conditions.
5.4 The results obtained with a mechanical muller do not
necessarily correlate directly with an industrial situation where
This test method is under the jurisdiction of ASTM Committee D-1 on Paint
and Related Coatings, Materials, andApplications and is the direct responsibility of
different dispersing conditions exist. However, dispersion with
Subcommittee D01.26 on Optical Properties.
Current edition approved June 00, 2000. Published August 2000. Originally
published as D 387 – 34 T. Last previous edition D 387 – 86 (1994).
2 3
Annual Book of ASTM Standards, Vol 06.01. Annual Book of ASTM Standards, Vol 06.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D387
a mechanical muller is a quick and inexpensive way of testing vehicle. The conditions for obtaining the maximum tinting
the color and strength of a pigment for routine quality control. strength with the mechanical muller can be determined by
following the procedure in Annex A1.
6. Apparatus 9.2 If these conditions are known for a particular pigment
with a particular vehicle, or if the purchaser and seller agree
6.1 Balances—(1) A balance sensitive to 10 mg and (2)an
upon a particular set of conditions, there is no need to carry out
analytical balance sensitive to 1.0 mg.
the procedure in Annex A1.
6.2 Muller, Mechanical, equipped with ground-glass plates
to which a variable but known force may be added in 220-N
10. Dispersion Procedure
(50-lbf) increments. The driven glass plate shall have a speed
of rotation of between 70 and 120 r/min and the apparatus shall 10.1 Decide, by agreement or by experimentation, as dis-
have an arrangement for pre-setting the number of revolutions cussed in Section 9, the following dispersing conditions:
in multiples of 50. 10.1.1 Force applied to the muller plates;
6.3 Rubbing Surfaces—The rubbing surfaces of the ground 10.1.2 Number of revolutions;
glass plates shall be kept sharp by removing them from the 10.1.3 Mass of the pigment; and
muller and grinding them face-to-face with No. 303 optical 10.1.4 Mass of the vehicle.
emery, or its equivalent, and water. 10.2 Applying these decisions, prepare a dispersion of the
6.4 Small Glass Slab or other nonabsorbent material, reference standard pigment. Weigh onto a glass slab to within
suitable for weighing and mixing pigment pastes. 2 mg, the appropriate quantities of the standard pigment and
6.5 Spatula—Aflexiblespatulahavinga75to150-mm(3to the dispersing vehicle. Mix the pigment and vehicle together
6-in.) blade. thoroughly with the spatula and transfer the mixture to the
6.6 Paper Charts, white with a black band and a surface lower plate of the muller. Spread the mixture in a path
impervious to paint liquids. approximately 100 mm wide and halfway between the center
and rim of the lower plate, and clean the spatula as much as
6.7 Film Applicator, at least 75 mm (3 in.) wide with a
clearance of 100 µm (4 mils) to produce wet films about 50 µm possiblebywipingitontheupperplateofthemuller.Closethe
plates and carry out the mulling stages of 50 revolutions; after
(2 mils) thick.
6.8 Color-Measuring Instrument, meeting the requirements each stage collect the paste from both plates with the spatula
and spread it around the 100-mm path on the lower plate,
of Test Method D 2244.
wiping the spatula on the upper plate as before. When the
7. Materials mulling has been carried out for the prescribed number of
revolutions, collect the paste and store it. Clean the glass slab,
7.1 Reference Standard—A standard pigment of the same
the muller plates, and the spatula, and repeat the procedure
type and grade as the pigment to be tested, as agreed upon
with exactly the same quantities of the test sample and vehicle.
between the purchaser and the seller.
Collect the paste from this sample and store it. Clean the glass
7.2 Vehicle—A solvent-free vehicle, such as No. 1 litho-
slab, the muller plates, and the spatula.
graphic varnish, with 0.8 % each of cobalt and manganese
driers (6 % types).
NOTE 4—The most common sources of error in this procedure are
7.3 White Tinting Paste—Awhite paint compatible with the inaccurate weighing, incomplete transfer of the pigment and vehicle
mixture, and contamination of the plates by previous samples.
dispersion vehicle, such as 57 parts of rutile titanium dioxide
dispersed in 43 parts of the vehicle described in 7.2.
11. Masstone Color Procedure
NOTE 3—Because the choice of vehicle and white tinting pigment may
11.1 Draw down a portion of the test and standard pastes in
affect the results, they should be agreed upon between the purchaser and
juxtaposition on a paper chart over a vacuum-drawdown plate
the seller.
or other suitable plane surface with the film applicator. Make
8. Hazards sure that the coating is opaque.
11.2 Immediately compare the colors visually while still
8.1 Some pigments may be potentially toxic and therefore
wet, using Practice D 1729, and record the results. Set the
should be handled with care. Obtain specific precautions from
drawdowns aside in a dust-free area to dry. When dry, repeat
the manufacturer or supplier.
the visual color difference evaluation and record the results.
8.2 Manysolventsandpaintvehiclespresentexplosion,fire,
See Practice D 3964.
and toxicity hazards, and they should accordingly be handled
11.3 If desired, evaluate the color difference instrumentally
with care. Again, obtain specific precautions from the manu-
using Test Method D 2244, and report the color difference in
facturer or supplier.
units as agreed upon between the purchaser and seller.
9. Dispersing Conditions
NOTE 5—Wet color difference evaluations may not agree with dry color
difference evaluations because of such phenomena as flooding and
9.1 The conditions for dispersing the pigment on the me-
flocculation. In the case of a difference between the wet and dry
chanical muller should be such that the maximum tinting
evaluations, the purchaser and the seller should agree upon which
strength is developed. For each pigment and each dispersing
condition is the standard.
vehicle the development of tinting strength by the mechanical
NOTE 6—Color difference measurements of wet paints may require a
muller is influenced by the force applied, the number of
special adapter to protect the instrument from fouling. Because color
revolutions, the mass of the pigment, and the mass of the difference-measuring instruments differ widely in their design, the user
D387
2 2
may have to develop his own adapter.
TS 5 @~1 2 R ! /2R # / @~1 2 R ! /2R # ~T!
` ` u ` ` s
12. Tint Color Procedure
where:
TS 5 tinting strength of test pigment,
12.1 Determine by calculation the amount of white pigment
R 5 measured reflectant factor (as a decimal),
paste that must be added to 0.5 g of the color pigment paste so `
T 5 assigned tinti
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