ASTM D4838-88(2010)
(Test Method)Standard Test Method for Determining the Relative Tinting Strength of Chromatic Paints
Standard Test Method for Determining the Relative Tinting Strength of Chromatic Paints
SIGNIFICANCE AND USE
Tinting strength may be one factor in judging the relative economic value of paints, since pigment concentration contributes to strength in a major way; other factors are formulation and color development in grinding. The user may also select products for other properties, such as transparency, that are accompanied by different tinting strengths. The results of this test method may be used for production control or quality comparisons.
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 excessively high pigment concentration to obtain a desired color effect, and this may lead to defects in the dry paint film.
This test method applies only to single-pigment paints. The tinting strength of paints that contain two or more chromatic pigments with different optical properties cannot be evaluated by this test method.
The term “similar chemical type” used in 1.1 does not limit the ingredients in the paints to identity, but refers to compatibility in the case of vehicles and to similarity in the case of pigment types.
While the instrumental evaluation of tinting strength is described, visual comparisons can also be used, with lower precision, and should be made to provide confirmation of the instrumental and computational results.
If the sample and standard are widely different in appearance when prepared at the same ratio of chromatic to white paint, another sample should be prepared to bring the two closer in appearance, to obtain the most accurate results.
The quantities of chromatic and white paints mixed must be accurately known, on either a weight or a volume basis, but the concentration of pigment in the chromatic paint need not be known.
When the paints being compared have the same vehicle and pigment (same Colour Index name and number) the values of uncorrected tinting strength from 9.1 and corrected tinting strength from 9....
SCOPE
1.1 This test method describes the determination of the absorption tinting strength of a chromatic test paint relative to that of a standard or reference paint of the same chemical type. The procedures are based on dilution of the paints with a standard mixing white paint, followed by instrumental measurement and calculation. Provision is made for correcting the results for small differences in hue or chroma, or both, between the test and reference chromatic paints.
1.2 This test method is intended for the comparison of paints containing the same type of vehicle (acrylic, alkyd, or oil) and single-pigment colorants of the same Colour Index name and number. The amounts of the pigment and of the other components of the paint need not be known.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.4 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.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D4838 − 88 (Reapproved2010)
Standard Test Method for
Determining the Relative Tinting Strength of Chromatic
Paints
This standard is issued under the fixed designation D4838; 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 E284 Terminology of Appearance
E308 PracticeforComputingtheColorsofObjectsbyUsing
1.1 This test method describes the determination of the
the CIE System
absorption tinting strength of a chromatic test paint relative to
E1164 PracticeforObtainingSpectrometricDataforObject-
that of a standard or reference paint of the same chemical type.
Color Evaluation
The procedures are based on dilution of the paints with a
standard mixing white paint, followed by instrumental mea-
3. Terminology
surement and calculation. Provision is made for correcting the
resultsforsmalldifferencesinhueorchroma,orboth,between
3.1 Definitions:
the test and reference chromatic paints.
3.1.1 tinting strength, n—measure of the effectiveness with
whichaunitquantityofacolorantaltersthecolorofamaterial.
1.2 This test method is intended for the comparison of
For scattering and absorbing colorants (pigments), both ab-
paints containing the same type of vehicle (acrylic, alkyd, or
sorption and scattering tinting strength must be specified.
oil) and single-pigment colorants of the same Colour Index
nameandnumber.Theamountsofthepigmentandoftheother
3.1.2 tinting strength, absorption, n—relative change in the
components of the paint need not be known.
absorption properties of a standard white material when a
specified amount of an absorbing pigment, black or chromatic,
1.3 The values stated in SI units are to be regarded as the
is added to it.
standard. The values given in parentheses are for information
3.1.2.1 Discussion—This is the common definition of tint-
only.
ing strength; however, this definition of the term can be
1.4 This standard does not purport to address all of the
misleading. For example, the tinting strength of a yellow
safety concerns, if any, associated with its use. It is the
colorant depends on its scattering as well as its absorption. Its
responsibility of the user of this standard to establish appro-
tinting strength as determined from a mixture with white
priate safety and health practices and determine the applica-
provides no information about its behavior when mixed with
bility of regulatory limitations prior to use.
low-scattering colorants, such as a black.
2. Referenced Documents
3.1.3 tinting strength, scattering, n—relative change in the
scattering properties of a standard black material (with no
2.1 ASTM Standards:
white pigment present) when a specified amount of a white or
D1640 Test Methods for Drying, Curing, or Film Formation
chromatic scattering pigment is added to it.
of Organic Coatings at Room Temperature
D4303 Test Methods for Lightfastness of Colorants Used in
3.1.4 For other definitions, see Terminology E284.
Artists’ Materials
3.2 Definitions of Terms Specific to This Standard:
3.2.1 drawdown,n—alayerofpaintdepositedonasubstrate
by use of a drawdown bar to evaluate the characteristics of the
This test method is under the jurisdiction of ASTM Committee D01 on Paint
paint.
and Related Coatings, Materials, andApplications and is the direct responsibility of
Subcommittee D01.57 on Artist Paints and Related Materials.
3.2.2 drawdown bar, n—a bar designed to deposit a speci-
CurrenteditionapprovedJune1,2010.PublishedJuly2010.Originallyapproved
fied thickness of wet paint film uniformly on a specified test
in 1988. Last previous edition approved in 2003 as D4838 - 88 (2003). DOI:
10.1520/D4838-88R10. panel or other substrate.
Colour Index, The Society of Dyers and Colourists, London, 1987. Available
from theAmericanAssociation of Textile Chemists and Colorists, P.O. Box 12215,
4. Summary of Test Method
Research Triangle Park, NC 27709.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
4.1 Chromatic paints are diluted with white paint to obtain
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
mixtures that will produce a drawdown having 35 to 45 %
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. reflectance factor at the wavelength of maximum absorption.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4838 − 88 (2010)
4.2 Drawdowns of these mixture paints are produced at 5.9 Strictly speaking, the Kubelka-Munk-type analysis of
complete hiding. this test method should not be applied to the tristimulus filter
readings used, but only to spectral data. For the purposes of the
4.3 The drawdowns are measured to obtain tristimulus filter
relative comparisons of this test method, however, the errors
readings R, G, B either directly or by computation from CIE
introduced by the calculations used cancel to an adequate
tristimulus values X, Y, Z.
degree.
4.4 One of the samples is designated the standard, and the
percents of tinting strength, % TS, of the others are calculated
6. Apparatus and Materials
relativetothatofthestandard.Provisionismadeforcorrecting
6.1 Laboratory Balance, top-loading, having a sensitivity of
this tinting strength for small differences in hue, chroma, or
0.01 g.
both, between the standard and the test specimen, and for
6.2 Drawdown bars, capable of producing smooth paint
obtaining an average tinting strength and a range.
films with wet-film thicknesses between 0.075 and 0.25 mm
(0.003 and 0.010 in.).
5. Significance and Use
6.3 Opacity charts, sealed-paper type with black and white
5.1 Tinting strength may be one factor in judging the
areas.
relative economic value of paints, since pigment concentration
contributes to strength in a major way; other factors are 6.4 Color-Measuring Instrument , either a spectrophotom-
eter providing 1931 CIE tristimulus values X, Y, Z for CIE
formulation and color development in grinding. The user may
standard illuminant C, or a tristimulus colorimeter providing
also select products for other properties, such as transparency,
either such tristimulus values or colorimeter readings R, G, B.
that are accompanied by different tinting strengths. The results
of this test method may be used for production control or
6.5 Mixing White Paint, prepared as described in the Speci-
quality comparisons.
men Preparation, MixingWhites for Dilution of Colors section
of Test Methods D4303.Alternatively, a commercial titanium-
5.2 Theproductwiththegreatestortheleasttintingstrength
dioxide white artists’ paint may be used. The mixing white
may not be the most desirable for a given artistic use. For
paint must be made with the same vehicle type (acrylic, alkyd,
example, low tinting strength may lead to the need to use an
or oil) as the paints to be tested.
excessively high pigment concentration to obtain a desired
color effect, and this may lead to defects in the dry paint film.
7. Specimen Preparation
5.3 This test method applies only to single-pigment paints.
7.1 Obtain representative samples of the chromatic paints to
The tinting strength of paints that contain two or more
be tested. For tube paints, expel the entire contents of the tube
chromatic pigments with different optical properties cannot be
and mix thoroughly before sampling.
evaluated by this test method.
7.2 Determine the approximate amount of chromatic paint
5.4 The term “similar chemical type” used in 1.1 does not
tobeaddedto20gofmixingwhitepainttoobtainadrawdown
limit the ingredients in the paints to identity, but refers to
with 35 to 45 % reflectance factor at the wavelength of
compatibility in the case of vehicles and to similarity in the
maximum absorption. If the amount of chromatic paint is not
case of pigment types.
known in advance, consult the table in Appendix X1. For
5.5 While the instrumental evaluation of tinting strength is
pigments other than those listed, use as the general guideline
described, visual comparisons can also be used, with lower
the addition of5gof chromatic paint containing an inorganic
precision, and should be made to provide confirmation of the
pigment or1gof chromatic paint containing an organic
instrumental and computational results. pigment to the 20 g of mixing white paint.
5.6 If the sample and standard are widely different in NOTE 1—Appendix X1 of Test Methods D4303 describes a method for
computing the necessary adjustments in quantities required if additional
appearance when prepared at the same ratio of chromatic to
trials are needed to obtain the desired level of reflectance factor.
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
endofanopacitychartandpullingthedrawdownbarsmoothly
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 c
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