ASTM D4303-10(2022)
(Test Method)Standard Test Methods for Lightfastness of Colorants Used in Artists' Materials
Standard Test Methods for Lightfastness of Colorants Used in Artists' Materials
SIGNIFICANCE AND USE
5.1 The retention of chromatic properties by a colorant over a long period of years is essential in a work of art. Accelerated exposure simulates color changes that may reasonably be expected. The producer and the user of artists' materials, therefore, can be apprised of suitable colorants.
5.2 Variations in results may be expected between the test methods. Also, some variation may be expected when the same test is repeated. Variations in Methods A and B are due to differences in outdoor conditions that are not accounted for in testing to equivalent radiant exposures. Information on sources of variability and strategies for addressing variability in laboratory accelerated exposure tests is found in Guide G141.
5.3 This standard does not cover factors other than lightfastness that can affect the permanence of art materials.
SCOPE
1.1 Four test methods to accelerate the effects of long term indoor illumination on artists’ materials are described below. One of the natural daylight methods and one of the xenon-arc methods are used to categorize the lightfastness of colorants.
1.1.1 Test Method A—Exposure in southern Florida to natural daylight filtered through window glass.
1.1.2 Test Method B—Exposure in Arizona to natural daylight filtered through window glass.
1.1.3 Test Method C—Exposure in a non-humidity controlled xenon-arc device simulating daylight filtered through window glass.
1.1.4 Test Method D—Exposure in a humidity controlled xenon-arc device simulating daylight filtered through window glass.
1.2 These test methods are used to approximate the color change that can be expected over time in colorants used in artists' materials exposed indoors to daylight through window glass.
Note 1: The color changes that result from accelerated exposure may not duplicate the results of normal indoor exposure in a home, art gallery, or museum. The relative resistance to change, however, can be established so colored materials can be assigned to categories of relative lightfastness.
Note 2: Users who wish to test colored materials under fluorescent illumination should consult Practice D4674.
1.3 Lightfastness categories are established to which colorants are assigned based on the color difference between specimens before and after exposure.
1.4 Color difference units are calculated by the CIE 1976 L*a*b* color difference equation.
1.5 These test methods apply to colored artists’ materials.
1.6 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.7 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.8 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.
General Information
Relations
Standards Content (Sample)
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: D4303 − 10 (Reapproved 2022)
Standard Test Methods for
Lightfastness of Colorants Used in Artists’ Materials
This standard is issued under the fixed designation D4303; 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 responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
1.1 Four test methods to accelerate the effects of long term
mine the applicability of regulatory limitations prior to use.
indoor illumination on artists’ materials are described below.
1.8 This international standard was developed in accor-
One of the natural daylight methods and one of the xenon-arc
dance with internationally recognized principles on standard-
methods are used to categorize the lightfastness of colorants.
ization established in the Decision on Principles for the
1.1.1 Test Method A—Exposure in southern Florida to
Development of International Standards, Guides and Recom-
natural daylight filtered through window glass.
mendations issued by the World Trade Organization Technical
1.1.2 Test Method B—Exposure in Arizona to natural day-
Barriers to Trade (TBT) Committee.
light filtered through window glass.
1.1.3 Test Method C—Exposure in a non-humidity con-
2. Referenced Documents
trolled xenon-arc device simulating daylight filtered through
2.1 ASTM Standards:
window glass.
D2244 Practice for Calculation of Color Tolerances and
1.1.4 Test Method D—Exposure in a humidity controlled
Color Differences from Instrumentally Measured Color
xenon-arc device simulating daylight filtered through window
Coordinates
glass.
D4302 Specification for Artists’ Oil, Resin-Oil, and Alkyd
1.2 These test methods are used to approximate the color
Paints
change that can be expected over time in colorants used in
D4674 PracticeforAcceleratedTestingforColorStabilityof
artists’ materials exposed indoors to daylight through window
Plastics Exposed to Indoor Office Environments
glass.
D5067 Specification for Artists’ Watercolor Paints
NOTE 1—The color changes that result from accelerated exposure may
D5098 Specification for Artists’Acrylic Dispersion Paints
not duplicate the results of normal indoor exposure in a home, art gallery,
D5724 Specification for Gouache Paints
or museum.The relative resistance to change, however, can be established
D6901 Specification for Artists’ Colored Pencils
so colored materials can be assigned to categories of relative lightfastness.
E284 Terminology of Appearance
NOTE 2—Users who wish to test colored materials under fluorescent
illumination should consult Practice D4674. E1347 Test Method for Color and Color-Difference Mea-
surement by Tristimulus Colorimetry
1.3 Lightfastness categories are established to which colo-
E1348 Test Method for Transmittance and Color by Spec-
rants are assigned based on the color difference between
trophotometry Using Hemispherical Geometry
specimens before and after exposure.
E1349 Test Method for Reflectance Factor and Color by
1.4 Color difference units are calculated by the CIE 1976
Spectrophotometry Using Bidirectional (45°:0° or 0°:45°)
L*a*b* color difference equation.
Geometry
1.5 These test methods apply to colored artists’ materials. G24 Practice for Conducting Exposures to Daylight Filtered
Through Glass
1.6 The values stated in SI units are to be regarded as the
G113 Terminology Relating to Natural andArtificial Weath-
standard. The values given in parentheses are for information
ering Tests of Nonmetallic Materials
only.
G141 Guide for Addressing Variability in Exposure Testing
1.7 This standard does not purport to address all of the
of Nonmetallic Materials
safety concerns, if any, associated with its use. It is the
G151 Practice for Exposing Nonmetallic Materials inAccel-
erated Test Devices that Use Laboratory Light Sources
These test methods are under the jurisdiction of ASTM Committee D01 on
Paint and Related Coatings, Materials, and Applications and are the direct
responsibility of Subcommittee D01.57 on Artist Paints and Related Materials. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Dec. 1, 2022. Published December 2022. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1983. Last previous edition approved in 2016 as D4303 – 10 (2016). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D4303-10R22. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4303 − 10 (2022)
G155 Practice for Operating XenonArc LampApparatus for 6.3 Spectrophotometer, abridged spectrophotometer or colo-
Exposure of Materials rimeter capable of excluding specular reflectance in its mea-
surement.
3. Terminology
3.1 Definitions—Appearance terms used in these test meth-
7. Procedure
ods are defined in Terminology E284. Terms relating to natural
7.1 Prepare seven specimens of the art materials to be
and artificial lightfastness tests are defined in Terminology
tested, following the directions given in the appropriate speci-
G113.
fication. If there is no specification for the art material, seven
3.1.1 glass, n—as used in these test methods, glass refers to
specimens must be prepared that are as similar, uniform, and
single-strength window glass.
opaque as possible.
4. Summary of Test Method
7.1.1 Two specimens of each color shall be exposed in each
4.1 Color measurements are made on duplicate specimens of two test methods, either A or B and either C or D. One
that have been prepared as directed in the specification for that
specimen of each color shall be retained for a visual compari-
material. Examples of specifications are: D4302, D5067, son with the test specimens following exposure, and two
D5098, D5724, and D6901. Each contains colorants in a
specimens shall be retained for use in a third exposure if
different vehicle. The measurements are recorded for compari-
needed.
son with readings made after the specimens have been ex-
7.1.2 The retained, unexposed specimens are stored in the
posed.
dark unless the formulation contains oil. Store specimens that
4.2 Lightfastness is determined by exposing the specimens contain oil in a light level of 500 lux to 700 lux (50 fc to 75 fc)
to prevent yellowing. If specimens must be stored for as long
to daylight filtered through glass outdoors either in southern
Florida or inArizona and also to xenon arc radiation through a as 100 days, store all specimens in the dark, but remove those
window glass filter.
containing oil and place in the light level specified above to
prevent yellowing for at least 7 days before measurement or
4.3 The colorants are classified by the amount of color
visual evaluation.
change calculated as ∆E* units in accordance with Practice
7.1.3 Cut the specimen to a size that will fit the holder to be
D2244.
used for exposure and the port of the color measuring instru-
4.4 Variations in test results can be due to differences in
ment.
specimen preparation, surface irregularities, color measure-
7.1.4 Determine if test specimens are opaque. Colors mixed
ments and conditions of exposure. Allowance for these varia-
with white, as described in the specifications for artists’paints,
tions is made by assigning a wide range of color change n each
are opaque. Other materials must be applied over both a black
of the five lightfastness categories. Colorants are placed in one
substrate and a white substrate to determine opacity. Any
of these categories based on the mean of the ∆E* values
measured color difference between the color over black and
obtained from two or more types of exposure. Only colorants
over white indicates a lack of opacity.
that place in the first two categories conform to the require-
ments of this standard.
7.1.4.1 A measurement representative of the whole speci-
men must be obtained if the specimen is not opaque. To get a
5. Significance and Use
representative measure of the color, both before and after
5.1 The retention of chromatic properties by a colorant over
exposure.either(1)usealargemeasuringportof25mm(1in.)
a long period of years is essential in a work of art.Accelerated
diameter,or(2)usingasmallport,obtainthemeanofanumber
exposure simulates color changes that may reasonably be
of measurements of various areas of the specimens, and
expected. The producer and the user of artists’ materials,
compare it with the mean of a second set of measurements of
therefore, can be apprised of suitable colorants.
different areas. If the means agree, use that value as the
representative color. Otherwise, repeat the procedure until
5.2 Variations in results may be expected between the test
agreement is obtained.
methods.Also, some variation may be expected when the same
test is repeated. Variations in Methods A and B are due to
7.2 Immediately before exposure, measure all test speci-
differences in outdoor conditions that are not accounted for in
mens using a spectrophotometer or spectrocolorimeter (see
testing to equivalent radiant exposures. Information on sources
Test Method E1348 or E1349) or colorimeter (seeTest Method
of variability and strategies for addressing variability in labo-
E1347) using Illuminant D65 and the 1964 10° Observer and
ratory accelerated exposure tests is found in Guide G141.
excluding specular reflection from the measurement. Record
5.3 This standard does not cover factors other than light- the CIELAB measurement data.
fastness that can affect the permanence of art materials.
7.2.1 Measure specimen panels with any brush marks in the
same direction and measure the same area of the panel before
6. Apparatus
andaftereachexposureinterval.Ifthedesignoftheinstrument
6.1 Outdoor Exposure Facilities as described in Practice
allows, three readings at different locations on the panel should
G24, using an exposure angle of 45°, facing the equator.
be made and the mean calculated. If feasible, mark on the back
6.2 Xenon-Arc Lightfastness Apparatus as described in of the specimen the spot(s) measured, and remeasure these
Practice G155. same spots following exposure.
D4303 − 10 (2022)
NOTE 3—The set points specified for irradiance, temperature and
7.3 Expose duplicate specimens in each of two test
humidity are the target conditions for the sensor programmed by the user
methods, outdoor Test Method A or B and xenon arc Test
at the control point. Therefore, when a standard calls for a particular set
Method C or D, as described below:
point, the user programs that exact number. The operational fluctuation
7.3.1 Test Method A—Exposure in Southern Florida Below
specified with the set point does not imply that the user is allowed to
27° Latitude to Natural Daylight Filtered Through Window program a set point higher or lower than the exact set point specified.
Operational fluctuation is determined by the machine variable and is the
Glass—Test Method A can be used for under glass outdoor
maximum deviation allowable from the set point of the sensor at the
exposure if the material is an oil paint or acrylic dispersion
control point during equilibrium conditions.
paint on an aluminum substrate.
NOTE 4—To track the rate of color change in the xenon arc exposure,
7.3.1.1 Mount duplicate specimens of each color on an open
the total exposure time can be divided into three or more phases and the
device programmed to stop at the end of each phase so the specimens can
sided rack under glass and expose in southern Florida at a 45
be measured and recorded. Then specimens are returned to the test
degree angle to the horizontal facing south during October
chamber and exposure continues until the total required amount of
through May to a total global solar (290 nm to 2500 nm)
irradiation is reached.
radiation dose of 1260 MJ/m incident on the glass, in
7.3.4 Test Method D—Exposure Simulating Daylight Fil-
accordance with Practice G24.
tered Through Window Glass in a Humidity Controlled Xenon-
7.3.2 Test Method B—Exposure in Arizona to Natural Day-
Arc Device—This environment will typically have higher
light Filtered Through Window Glass—Use Test Method B if
relative humidity than Test Method C:
the test specimens are prepared on a paper substrate or the
7.3.4.1 Follow 7.3.3.1.
vehicle is affected by the combination of high moisture content
and temperature fluctuations that are characteristic of south 7.3.4.2 Mount specimens in unbacked holders and follow
Florida. Examples are watercolor and gouache paints, colored step (a)in 7.3.3.1. It is recommended that all unused spaces in
pencils, colored water-thinned inks, and pastels. the specimen exposure area be filled with blank metal panels
that are not highly reflective.
7.3.2.1 Mountduplicatespecimensinanenclosedblackbox
with a small fan to circulate the air and expose inArizona at a 7.3.4.3 Follow 7.3.3.2.
45 degree angle to the horizontal facing south during October
7.3.4.4 Follow 7.3.3.3.
through May to a total global solar (290 nm to 2500 nm)
7.3.4.5 Set the relative humidity at the control point in the
radiation dose of 1260 MJ/m incident on the glass, in
test chamber to 55 6 5 % RH.
accordance with Practice G24.
7.3.4.6 In machines that allow control of chamber air
7.3.3 Test Method C—Exposure Simulating Daylight Fil-
temperature, it shall be set at 43 °C 6 2 °C.
tered Through Window Glass in a Xenon Arc Device That Does
NOTE 5—Duplicate specimens should not be placed near one another
Not Control the Relative Humidity—This method will gener-
during the exposures.
ally have a low relative humidity.
NOTE 6—It has been found that Alizarin Crimson and other colorants
7.3.3.1 Use a xenon-arc device that conforms to the require-
are affected differently when exposed to a light/dark cycle rather than to
ments defined in Practices G151 and G155. Unless otherwise
continuouslight.Darkperiodsarecharacteristicofexposuretodaylightas
specified, the spectral power distribution of the xenon-arc shall
well as to indoor lighting. Therefore, when mutually agreed upon, the
followingalternativelightanddarkcyclemaybeemployedasanalternate
conform to the requirements in Practice G155 for xenon arc
constantlight:3.8hlightfollowedby1hdark.Duringthelightperiod,the
radiation through a window glass filter.
conditions of irradiance, temperature and humidity are as g
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