ASTM D4838-88(1998)

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 4838 – 88 (Reapproved 1998)
Standard Test Method for
Determining the Relative Tinting Strength of Chromatic
Paints
This standard is issued under the fixed designation D 4838; 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.
1. Scope 3.1.1 tinting strength—measure of the effectiveness with
which a unit quantity of a colorant alters the color of a material.
1.1 This test method describes the determination of the
For scattering and absorbing colorants (pigments), both ab-
absorption tinting strength of a chromatic test paint relative to
sorption and scattering tinting strength must be specified.
that of a standard or reference paint of the same chemical type.
3.1.2 tinting strength, absorption—relative change in the
The procedures are based on dilution of the paints with a
absorption properties of a standard white material when a
standard mixing white paint, followed by instrumental mea-
specified amount of an absorbing pigment, black or chromatic,
surement and calculation. Provision is made for correcting the
is added to it.
results for small differences in hue or chroma, or both, between
3.1.2.1 Discussion—This is the common definition of tint-
the test and reference chromatic paints.
ing strength; however, this definition of the term can be
1.2 This test method is intended for the comparison of
misleading. For example, the tinting strength of a yellow
paints containing the same type of vehicle (acrylic, alkyd, or
colorant depends on its scattering as well as its absorption. Its
oil) and single-pigment colorants of the same Colour Index
tinting strength as determined from a mixture with white
name and number. The amounts of the pigment and of the other
provides no information about its behavior when mixed with
components of the paint need not be known.
low-scattering colorants, such as a black.
1.3 This standard does not purport to address all of the
3.1.3 tinting strength, scattering—relative change in the
safety concerns, if any, associated with its use. It is the
scattering properties of a standard black material (with no
responsibility of the user of this standard to establish appro-
white pigment present) when a specified amount of a white or
priate safety and health practices and determine the applica-
chromatic scattering pigment is added to it.
bility of regulatory limitations prior to use.
3.1.4 For other definitions, see Terminology E 284.
2. Referenced Documents 3.2 Definitions of Terms Specific to This Standard:
3.2.1 drawdown—a layer of paint deposited on a substrate
2.1 ASTM Standards:
by use of a drawdown bar to evaluate the characteristics of the
D 1640 Test Methods for Drying, Curing, or Film Forma-
paint.
tion of Organic Coatings at Room Temperature
3.2.2 drawdown bar—a bar designed to deposit a specified
D 4303 Test Methods for Lightfastness of Pigments Used in
thickness of wet paint film uniformly on a specified test panel
Artists’ Paints
or other substrate.
E 284 Terminology of Appearance
E 308 Practice for Computing the Colors of Objects by
4. Summary of Test Method
Using the CIE System
4.1 Chromatic paints are diluted with white paint to obtain
E 1164 Practice for Obtaining Spectrophotometric Data for
3 mixtures that will produce a drawdown having 35 to 45 %
Object-Color Evaluation
reflectance factor at the wavelength of maximum absorption.
3. Terminology 4.2 Drawdowns of these mixture paints are produced at
complete hiding.
3.1 Definitions:
4.3 The drawdowns are measured to obtain tristimulus filter
readings R, G, B either directly or by computation from CIE
This test method is under the jurisdiction of ASTM Committee D-1 on Paint
tristimulus values X, Y, Z.
and Related Coatings, Materials, and Applications and is the direct responsibility of
4.4 One of the samples is designated the standard, and the
Subcommittee D01.57 on Artist Paints and Related Materials.
percents of tinting strength, % TS, of the others are calculated
Current edition approved June 24, 1988. Published November 1988.
Colour Index, The Society of Dyers and Colourists, London, 1987. Available
relative to that of the standard. Provision is made for correcting
from the American Association of Textile Chemists and Colorists, P.O. Box 12215,
this tinting strength for small differences in hue, chroma, or
Research Triangle Park, NC 27709.
3 both, between the standard and the test specimen, and for
Annual Book of ASTM Standards, Vol 06.01.
obtaining an average tinting strength and a range.
Annual Book of ASTM Standards, Vol 06.02.
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NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 4838 – 88 (1998)
5. Significance and Use 6.4 Color-Measuring Instrument, either a spectrophotom-
eter providing 1931 CIE tristimulus values X, Y, Z for CIE
5.1 Tinting strength may be one factor in judging the
standard illuminant C, or a tristimulus colorimeter providing
relative economic value of paints, since pigment concentration
either such tristimulus values or colorimeter readings R, G, B.
contributes to strength in a major way; other factors are
6.5 Mixing White Paint, prepared as described in the Speci-
formulation and color development in grinding. The user may
men Preparation, Mixing Whites for Dilution of Colors section
also select products for other properties, such as transparency,
that are accompanied by different tinting strengths. The results of Test Method D 4303. Alternatively, a commercial titanium-
of this test method may be used for production control or dioxide white artists’ paint may be used. The mixing white
quality comparisons. paint must be made with the same vehicle type (acrylic, alkyd,
or oil) as the paints to be tested.
5.2 The product with the greatest or the least tinting strength
may not be the most desirable for a given artistic use. For
example, low tinting strength may lead to the need to use an 7. Specimen Preparation
excessively high pigment concentration to obtain a desired
7.1 Obtain representative samples of the chromatic paints to
color effect, and this may lead to defects in the dry paint film.
be tested. For tube paints, expel the entire contents of the tube
5.3 This test method applies only to single-pigment paints.
and mix thoroughly before sampling.
The tinting strength of paints that contain two or more
7.2 Determine the approximate amount of chromatic paint
chromatic pigments with different optical properties cannot be
to be added to 20 g of mixing white paint to obtain a drawdown
evaluated by this test method.
with 35 to 45 % reflectance factor at the wavelength of
5.4 The term “similar chemical type” used in 1.1 does not
maximum absorption. If the amount of chromatic paint is not
limit the ingredients in the paints to identity, but refers to
known in advance, consult the tables in Appendix X1. For
compatibility in the case of vehicles and to similarity in the
pigments other than those listed, use as the general guideline
case of pigment types.
the addition of5gof chromatic paint containing an inorganic
5.5 While the instrumental evaluation of tinting strength is
pigment or1gof chromatic paint containing an organic
described, visual comparisons can also be used, with lower
pigment to the 20 g of mixing white paint.
precision, and should be made to provide confirmation of the
instrumental and computational results.
NOTE 1—Appendix X1 of Test Method D 4303 describes a method for
5.6 If the sample and standard are widely different in
computing the necessary adjustments in quantities required if additional
trials are needed to obtain the desired level of reflectance factor.
appearance when prepared at the same ratio of chromatic to
white paint, another sample should be prepared to bring the
7.3 Weigh out the chromatic and mixing white paints to the
two closer in appearance, to obtain the most accurate results.
nearest 0.01 g, and mix thoroughly.
5.7 The quantities of chromatic and white paints mixed
7.4 Prepare drawdowns by placing the paint mixture at one
must be accurately known, on either a weight or a volume
end of an opacity chart and pulling the drawdown bar smoothly
basis, but the concentration of pigment in the chromatic paint
through the paint and across the chart. Paste paints should be
need not be known.
spread with a spatula or palette knife over the entire chart area
5.8 When the paints being compared have the same vehicle
to be covered before pulling the bar down the chart.
and pigment (same Colour Index name and number) the values
7.5 Allow the drawdowns to reach the dry-to-touch time as
of uncorrected tinting strength from 9.1 and corrected tinting
described in the Procedure section of Test Method D 1640.
strength from 9.2 should be nearly the same. If they are not, an
Acrylic paints should dry in air overnight. Alkyd paints may
average of the two tinting strengths is recommended as the best
require 5 days to dry. Oil paints may require 2 months to dry.
estimate of the true value, and a range provides a measure of
7.6 Determine whether each drawdown is at complete
the magnitude of the uncertainty, which is due to differences in
hiding by measuring the portions of it over the black and over
hue or chroma, o
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