ASTM D4838-88(2003)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information.
Designation:D4838–88(Reapproved2003)
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 E308 Practice for Computing the Colors of Objects by
Using the CIE System
1.1 This test method describes the determination of the
E1164 Practice for Obtaining Spectrometric Data for
absorption tinting strength of a chromatic test paint relative to
Object-Color Evaluation
that of a standard or reference paint of the same chemical type.
The procedures are based on dilution of the paints with a
3. Terminology
standard mixing white paint, followed by instrumental mea-
3.1 Definitions:
surement and calculation. Provision is made for correcting the
3.1.1 tinting strength—measure of the effectiveness with
resultsforsmalldifferencesinhueorchroma,orboth,between
whichaunitquantityofacolorantaltersthecolorofamaterial.
the test and reference chromatic paints.
For scattering and absorbing colorants (pigments), both ab-
1.2 This test method is intended for the comparison of
sorption and scattering tinting strength must be specified.
paints containing the same type of vehicle (acrylic, alkyd, or
3.1.2 tinting strength, absorption—relative change in the
oil) and single-pigment colorants of the same Colour Index
absorption properties of a standard white material when a
nameandnumber.Theamountsofthepigmentandoftheother
specified amount of an absorbing pigment, black or chromatic,
components of the paint need not be known.
is added to it.
1.3 The values stated in SI units are to be regarded as the
3.1.2.1 Discussion—This is the common definition of tint-
standard. The values given in parentheses are for information
ing strength; however, this definition of the term can be
only.
misleading. For example, the tinting strength of a yellow
1.4 This standard does not purport to address all of the
colorant depends on its scattering as well as its absorption. Its
safety concerns, if any, associated with its use. It is the
tinting strength as determined from a mixture with white
responsibility of the user of this standard to establish appro-
provides no information about its behavior when mixed with
priate safety and health practices and determine the applica-
low-scattering colorants, such as a black.
bility of regulatory limitations prior to use.
3.1.3 tinting strength, scattering—relative change in the
2. Referenced Documents scattering properties of a standard black material (with no
white pigment present) when a specified amount of a white or
2.1 ASTM Standards:
chromatic scattering pigment is added to it.
D1640 TestMethodsforDrying,Curing,orFilmFormation
3.1.4 For other definitions, see Terminology E284.
of Organic Coatings at Room Temperature
3.2 Definitions of Terms Specific to This Standard:
D4303 Test Methods for Lightfastness of Colorants Used in
3.2.1 drawdown—a layer of paint deposited on a substrate
Artists’ Materials
by use of a drawdown bar to evaluate the characteristics of the
E284 Terminology of Appearance
paint.
3.2.2 drawdown bar—a bar designed to deposit a specified
This test method is under the jurisdiction of ASTM Committee D01 on Paint
thickness of wet paint film uniformly on a specified test panel
and Related Coatings, Materials, andApplications and is the direct responsibility of
or other substrate.
Subcommittee D01.57 on Artist Paints and Related Materials.
Current edition approved May 10, 2003. Published June 2003. Originally
4. Summary of Test Method
approved in 1988. Last previous edition approved in 1988 as D4838 - 88 (1998).
DOI: 10.1520/D4838-88R03.
4.1 Chromatic paints are diluted with white paint to obtain
Colour Index, The Society of Dyers and Colourists, London, 1987. Available
mixtures that will produce a drawdown having 35 to 45 %
from theAmericanAssociation of Textile Chemists and Colorists, P.O. Box 12215,
reflectance factor at the wavelength of maximum absorption.
Research Triangle Park, NC 27709.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
4.2 Drawdowns of these mixture paints are produced at
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
complete hiding.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D4838–88 (2003)
4.3 The drawdowns are measured to obtain tristimulus filter 6. Apparatus and Materials
readings R, G, B either directly or by computation from CIE
6.1 Laboratory Balance, top-loading, having a sensitivity of
tristimulus values X, Y, Z.
0.01 g.
4.4 One of the samples is designated the standard, and the
6.2 Drawdown bars, capable of producing smooth paint
percents of tinting strength, % TS, of the others are calculated
films with wet-film thicknesses between 0.075 and 0.25 mm
relativetothatofthestandard.Provisionismadeforcorrecting
(0.003 and 0.010 in.).
this tinting strength for small differences in hue, chroma, or
6.3 Opacity charts, sealed-paper type with black and white
both, between the standard and the test specimen, and for
areas.
obtaining an average tinting strength and a range.
6.4 Color-Measuring Instrument, either a spectrophotom-
eter providing 1931 CIE tristimulus values X, Y, Z for CIE
5. Significance and Use
standard illuminant C, or a tristimulus colorimeter providing
either such tristimulus values or colorimeter readings R, G, B.
5.1 Tinting strength may be one factor in judging the
6.5 Mixing White Paint, prepared as described in the Speci-
relative economic value of paints, since pigment concentration
men Preparation, MixingWhites for Dilution of Colors section
contributes to strength in a major way; other factors are
of Test Methods D4303.Alternatively, a commercial titanium-
formulation and color development in grinding. The user may
dioxide white artists’ paint may be used. The mixing white
also select products for other properties, such as transparency,
paint must be made with the same vehicle type (acrylic, alkyd,
that are accompanied by different tinting strengths. The results
or oil) as the paints to be tested.
of this test method may be used for production control or
quality comparisons.
7. Specimen Preparation
5.2 Theproductwiththegreatestortheleasttintingstrength
7.1 Obtain representative samples of the chromatic paints to
may not be the most desirable for a given artistic use. For
be tested. For tube paints, expel the entire contents of the tube
example, low tinting strength may lead to the need to use an
and mix thoroughly before sampling.
excessively high pigment concentration to obtain a desired
7.2 Determine the approximate amount of chromatic paint
color effect, and this may lead to defects in the dry paint film.
tobeaddedto20gofmixingwhitepainttoobtainadrawdown
5.3 This test method applies only to single-pigment paints.
with 35 to 45 % reflectance factor at the wavelength of
The tinting strength of paints that contain two or more
maximum absorption. If the amount of chromatic paint is not
chromatic pigments with different optical properties cannot be
known in advance, consult the tables in Appendix X1. For
evaluated by this test method.
pigments other than those listed, use as the general guideline
5.4 The term “similar chemical type” used in 1.1 does not
the addition of5gof chromatic paint containing an inorganic
limit the ingredients in the paints to identity, but refers to
pigment or1gof chromatic paint containing an organic
compatibility in the case of vehicles and to similarity in the
pigment to the 20 g of mixing white paint.
case of pigment types.
5.5 While the instrumental evaluation of tinting strength is NOTE 1—Appendix X1 of Test Methods D4303 describes a method for
computing the necessary adjustments in quantities required if additional
described, visual comparisons can also be used, with lower
trials are needed to obtain the desired level of reflectance factor.
precision, and should be made to provide confirmation of the
instrumental and computational results.
7.3 Weigh out the chromatic and mixing white paints to the
5.6 If the sample and standard are widely different in nearest 0.01 g, and mix thoroughly.
appearance when prepared at the same ratio of chromatic to 7.4 Prepare drawdowns by placing the paint mixture at one
white paint, another sample should be prepared to bring the endofanopacitychartandpullingthedrawdownbarsmoothly
two closer in appearance, to obtain the most accurate results.
through the paint and across the chart. Paste paints should be
spread with a spatula or palette knife over the entire chart area
5.7 The quantities of chromatic and white paints mixed
must be accurately known, on either a weight or a volume to be covered before pulling the bar down the chart.
7.5 Allow the drawdowns to reach the dry-to-touch time as
basis, but the concentration of pigment in the chromatic paint
need not be known. described in the Procedure section of Test Methods D1640.
Acrylic paints should dry in air overnight. Alkyd paints may
5.8 When the paints being compared have the same vehicle
require
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