ASTM D4303-99

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.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 4303 – 99
Standard Test Methods for
Lightfastness of Pigments Used in Artists’ Paints
This standard is issued under the fixed designation D 4303; 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 D 4302 Specification for Artists’ Oil, Resin–Oil, and Alkyd
Paints
1.1 Four test methods to accelerate the effects of long term
D 4674 Test Method for Accelerated Testing for Color
indoor illumination on artists’ paints are described as follows:
Stability of Plastics Exposed to Indoor Fluorescent Light-
1.1.1 Test Method A—Exposure to natural daylight filtered
ing and Window Filtered Daylight
through glass,
D 5067 Specification for Artists’ Watercolor Paints
1.1.2 Test Method B—Exposure to irradiance from daylight
D 5098 Specification for Artists’ Acrylic Emulsion Paints
fluorescent lamps,
D 5724 Specification for Gouache Paints
1.1.3 Test Method C—Exposure in xenon-arc irradiance
E 284 Terminology of Appearance
simulating daylight filtered through glass, and
E 1347 Test Method for Color and Color–Difference Mea-
1.1.4 Test Method D—Exposure to irradiance from cool
surement by Tristimulus (Filter) Colorimetry
white fluorescent lamps and soda-lime glass filtered fluorescent
E 1348 Test Method for Transmittance and Color by Spec-
UV sunlamps.
trophotometry Using Hemispherical Geometry
1.2 These test methods are used to approximate the color
E 1349 Test Method for Reflectance Factor and Color by
change that can be expected over time in pigments used in
Spectrophotometry Using Bidirectional Geometry
artists’ paints in normal indoor exposure.
G 24 Practice for Conducting Natural Light Exposures Un-
NOTE 1—The color changes that result from accelerated exposure may 5
der Glass
not duplicate the results of normal indoor exposure in a home or gallery.
G 113 Terminology Relating to Natural and Artificial
The relative resistance to change, however, can be established so pigments
Weathering Tests of Nonmetallic Materials
can be assigned to categories of relative lightfastness.
G 151 Practice for Exposing Nonmetallic Materials in Ac-
1.3 Lightfastness categories are established to which pig- 5
celerated Test Devices that Use Laboratory Light Sources
ments are assigned based on the color difference between
G 155 Practice for Operating Xenon Arc Light Apparatus
specimens before and after exposure. 5
for Exposure of Nonmetallic Materials
1.4 Color difference units are calculated by the CIE 1976
L*a*b* color difference equation.
3. Terminology
1.5 These test methods apply to artists’ oil, resin-oil, acrylic
3.1 Definitions—Appearance terms used in these test meth-
emulsion, alkyd, watercolor paints, and gouache paints.
ods are defined in Definitions E 284. Terms relating to natural
1.6 This standard does not purport to address the safety
and artificial lightfastness tests are defined in Definitions
concerns, if any, associated with its use. It is the responsibility
G 113.
of the user of this standard to establish appropriate safety and
3.1.1 glass—as used in these test methods, glass refers to
health practices and determine the applicability of regulatory
single-strength window glass.
limitations prior to use.
4. Summary of Test Methods
2. Referenced Documents
4.1 Color measurements are made on specimens that have
2.1 ASTM Standards:
been prepared as directed in Specification D 4302, D 5067,
D 2244 Test Method for Calculation of Color Differences
D 5098 or D 5724 depending on the vehicle. The measure-
from Instrumentally Measured Color Coordinates
ments are recorded for comparison with readings made after
the specimens have been exposed.
These test methods are under the jurisdiction of ASTM Committee D-1 on Paint
and Related Coatings, Materials, and Applications and are the direct responsibility
of Subcommittee D01.57 on Artists’ Paints and Related Materials.
Current edition approved May 10, 1999. Published July 1999. Originally Annual Book of ASTM Standards, Vol 06.02.
published as D 4303 – 83. Last previous edition D 4303 – 98. Annual Book of ASTM Standards, Vol 08.03.
2 5
Annual Book of ASTM Standards, Vol 06.01. Annual Book of ASTM Standards, Vol 14.02.
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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.
D4303–99
4.2 Specimens are exposed to daylight filtered through glass 7.2.1 Read specimen panels always with any brush marks in
or to laboratory test sources to simulate and accelerate the the same direction and with panels in the same position so that
effects of indoor illumination using at least two of the four test the same area of the panel is measured before and after each
methods described in Section 7. exposure interval. If the design of the instrument allows, three
4.3 The pigments are classified by color difference calcu- readings at different locations on the panel should be made and
lated in accordance with Test Method D 2244. the mean calculated. If feasible, mark on the back of the
specimen the spot(s) measured, and remeasure these same
5. Significance and Use
spots following exposure.
5.1 The retention of chromatic properties by a pigment over 7.2.2 If it is necessary to store specimens in the dark for a
a long period of years is essential in an artistic painting. period of time, prior to measurement and exposure, those that
Accelerated exposure simulates color changes that may rea- contain oil in the vehicle shall be placed in subdued light for
sonably be expected. The producer and the user of artists’
seven days to eliminate any yellowing of the oil due to storage.
paints, therefore, can be apprised of suitable pigments.
7.2.3 Compare these pre-exposure measurements with sub-
5.2 There can be significant variations in results between the
sequent measurements of the test specimens made at the end of
different exposure procedures used in these test methods. In
exposure to calculate the amount of any color change. If
addition, there can also be significant differences in results
feasible, measure the test specimens at regular, frequent
between exposures conducted in accordance with a single
intervals during exposure to calculate the rate of any color
procedure because of variability inherent within the procedures
change.
themselves.
7.2.4 Retain a specimen of each paint in the dark. After the
test is complete, measure these retained specimens and com-
6. Apparatus
pare with the pre-exposure measurement of the test specimens
6.1 Sun Exposure Facilities as described in Practice G 24,
to verify that the retained specimens have not changed color
using an exposure angle of 45°, facing the equator.
significantly during storage.
6.2 Xenon-Arc Lightfastness Apparatus as described in
7.2.5 Compare visually the retained, unexposed specimens
Practice G 155.
with the exposed test specimens to verify that the measured
6.3 Daylight Fluorescent Lamp Apparatus, as described in
color difference agrees with the perceived color change be-
Annex A1.
tween the exposed and unexposed specimens. These retained
6.4 Fluorescent Cool White Lamp/Filtered Sunlamp Light-
specimens may also be needed for an additional test as
fastness Apparatus, using very high output cool white fluores-
described in 7.7.1 and 7.7.2.
cent lamps and soda-lime glass filtered fluorescent UV sun-
7.3 Expose specimen panels in at least two of the four test
lamps as described in Test Method D 4674.
methods described. Oil, resin-oil alkyd, and acrylic emulsion
6.5 Spectrophotometer, abridged spectrophotometer or
paint specimens shall be exposed by Test Method A and either
colorimeter capable of excluding specular reflectance in its
Test Method B, Test Method C or Test Method D. Watercolors,
measurement.
gouache, and other paints sensitive to moisture shall be
exposed by Test Methods C and either Test Method B or Test
7. Procedure
Method D.
7.1 Specimens of pigments to be tested in oil, resin-oil, or
7.3.1 Test Method A—Exposure to Natural Daylight Filtered
alkyd panels shall be prepared as directed in Specification
Through Glass:
D 4302. Specimens of pigments to be tested in acrylic emul-
7.3.1.1 Mount the specimens on an open-type rack and
sion paints shall be prepared as directed in Specification
expose at 45° angle to the vertical to a total radiation dose of
D 5098. Specimens of pigments to be tested in watercolors 2
1260 MJ/m in accordance with Practice G 24.
shall be prepared as directed in Specification D 5067.
7.3.1.2 For tests in southern Florida expose panels during
7.2 Immediately before exposure, measure all test speci-
the months of October through May.
mens on a spectrophotometer or spectrocolorimeter (see Test
7.3.2 Test Method B— Exposure to Irradiance from Day-
Method E 1348 or E 1349) or colorimeter (see Test Method
light Fluorescent Lamps:
E 1347) using Illuminant C and the 1931 2° observer and
7.3.2.1 Mount the specimens with the test face 3 in. (75
excluding specular reflection from the measurement. Record
mm) from the plane of the lamps.
the measurements.
7.3.2.2 Unless specified otherwise, expose the specimens to
a repeating cycle of 8 h light followed by 4 h dark until the
specimen has been exposed to a total radiant energy dose of
The Verlilux lamps F48T12VLX/HO, manufactured by Verilux, Inc., 9 Viaduct
1260 MJ/m . Rotate the specimen panels two positions to the
Rd., Stamford, CT 06906, used in the apparatus described in Annex A1 are not
available. Other fluorescent lamps that closely simulate daylight may be suitable,
right after each 100-MJ/m dose. This test method takes
and Subcommittee D01.57 seeks information that will allow these fluorescent lamps
approximately nine months to complete.
to be recommended. Lamps should have a related color temperature of 6000 6 500
7.3.2.3 Maintain the ambient room temperature at 24 6 3°C
K and a color rendenng index of at least 90 as calculated by Method of Measuring
and Specifying Colour-Rendering Properties of Light Sources, International Com-
and prevent the test chamber from exceeding room temperature
mission of Illumination (CIE) publication No. 13.2 (TC-3.2) 1974. Available from
by more than 6°C.
the U.S. National Committee of the CIE, c/o Director of Marketing, OEM Division,
7.3.2.4 Monitor irradiance at the specimen location for total
North American Philips Lighting Corp., Philip Square CN8800, Somerset, NJ
08873. radiation for each rotation period. Measure radiation 1 h after
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.
D4303–99
the lamps are turned on and at the end of the period. The mean both or the two reference paints show a color difference greater
of these readings in joules per square centimetre (J/cm ) per than four and less than 8 CIELAB units (CIELAB DE*>4.0
hour multiplied by the number of hours of radiation gives the and >8).
J/cm for that period.
7.3.4.2 Verify proper lamp function before starting test.
7.3.3 Test Method C— Exposure to Xenoc-Arc Irradiance Pre-age the lamps by leaving them on for a minimum of 48 h
Simulating Daylight Filtered Through Glass:
prior to the initial test. Radiometer readings at the start of the
7.3.3.1 Mount specimens in unbacked holders avoiding test shall not be less than 8.0 W/m for the 1500-mA lamps and
positions that place specimens at the extreme top or bottom of
1.0 W/m for the 430-mA lamps.
the specimen rack.
7.3.4.3 Adjust the specimens or specimen table so that the
7.3.3.2 Unless agreed otherwise, expose specimens in ac-
surface of all test specimens are within 3 mm of being coplanar
cordance with Practices G 151and G 155 to total radiation from
with the cosine receptor.
the filtered xenon arc to reach a radiant exposure of 510
7.3.4.4 Close the specimen drawer and verify lamp irradi-
kJ/m measured at 340 nm. Expose the specimens to 100 %
ance in accordance with 7.3.4.2.
light from the xenon arc apparatus equipped with window glass
7.3.4.5 Turn on both sets of lamps. After 20 min turn off
filters. Set the machine to maintain an irradiance level at 0.35
fluorescent sunlamps (FS) and record the cool white (CW)
W/m /nm at 340 nm and maintain the relative humidity in the
irradiance (radiometer reading) in W/m .
test chamber at 55 6 5 % RH. The black panel temperature
7.3.4.6 Turn off the CW lamps and turn on the FS lamps.
shall be 63 6 2°C. This radiant exposure measured at 340 nm
Record the radiometer reading (W/m ). Calculate the off-time
has been calculated to provide total UV radiant exposure
internal cycle of the FS lamp so the average nominal sunlamp
equivalent to the total UV behind glass-filtered daylight when
UV actinic exposure is set at 12 % of the value of the VHO
total spectral radiant exposure to glass-filtered daylight is 1260
lamps. An example calculation is as follows:
MJ/m . See Appendix X1.
Radiometer readings:
2 2
NOTE 2—When mutually agreed upon, the following alternative light
CW 5 10.3 W/m ,FS 5 2.4 W/m (1)
and dark cycle may be employed in accordance with Practices G 151 and
In1h:
G 155. Expose test specimens to the following cycle:
Set the xenon arc apparatus equipped with window glass filters to
CW radiation 5 10.3 W/m 3 3600 (2)
maintain an irradiance level of 0.35 W/m /nm at 340 nm.
5 s 37 080 J/m 3 0.12 5 4450
Light Cycle: 3.8 h light, at 35 6 5 % RH. The black panel temperature
2 2
shall be 63 6 2°C. Followed by:
FS radiation 5 2.4 W/m 3 3600 s 5 8640 J/m
Dark Cycle: 1 h dark, at 90 6 5 % RH. The black panel temperature
The On-Time required for the FS lamps is 4450/
shall be 35 6 3°C.
8640 = 0.515 h.
It has been found that Alizarin Crimson, and possibly other pigments,
The Off-Time interval is 0.485 h/h total operation of the unit.
are affected by a light and dark cycle, owing to the oxidation-reduction
effect of titanium dioxide changing valence with the changes from light to
7.3.4.7 Program the FS lamp cycling to a 1-h time on
dark and vice-versa, characteristic of daylight and indoor light.
interval/cycle.
Any variance from the specified test cycle must be detailed in the
7.3.4.8 Program the FS lamp timer to the off-time interval
Report section.
calculated in the example in 7.3.4.6.
7.3.4 Test Method D—Exposure to Irradiance From Very
7.3.4.9 Start the test. Do not add specimens once the test has
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