ASTM D8330-20

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: D8330 −20
Standard Specification for
Artists’ Pastels
This standard is issued under the fixed designation D8330; 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 G113 Terminology Relating to Natural andArtificial Weath-
ering Tests of Nonmetallic Materials
1.1 This specification establishes requirements for
G151 Practice for Exposing Nonmetallic Materials inAccel-
composition, performance, and labeling of artists’ pastels.
erated Test Devices that Use Laboratory Light Sources
1.2 This specification includes requirements for identifica-
G155 Practice for Operating XenonArc LightApparatus for
tion and lightfastness.
Exposure of Non-Metallic Materials
1.3 Pastel specimens are exposed to both natural daylight
through window glass and window glass-filtered simulated 3. Terminology
daylight radiation to determine the lightfastness category for
3.1 Definitions:
each pastel.
3.1.1 Refer to Terminology E284 for appearance terms used
1.4 The values stated in SI units are to be regarded as
in this specification and to Terminology G113 for terms
standard. The values given in parentheses after SI units are relating to natural and artificial lightness tests.
provided for information only and are not considered standard.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 pastel, n—a chalk-like stick, varying in hardness from
1.5 This international standard was developed in accor-
hard to soft, composed of minimal binder and colored and
dance with internationally recognized principles on standard-
white pigments for obtaining shades and tints.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
3.2.2 substrate, n—white, neutral pH, buffered, uncoated
mendations issued by the World Trade Organization Technical
paper, or board, without optical brighteners, to which pastel is
Barriers to Trade (TBT) Committee.
applied. Some substrates are coated with a gritty layer to aid in
adhesion—these are called sanded pastel papers or boards.
2. Referenced Documents
4. Significance and Use
2.1 ASTM Standards:
D1729 Practice for Visual Appraisal of Colors and Color
4.1 This specification establishes quality requirements and
Differences of Diffusely-Illuminated Opaque Materials
provides a basis for common understanding among producers,
D2244 Practice for Calculation of Color Tolerances and
distributors, and users.
Color Differences from Instrumentally Measured Color
4.2 It is not intended that all pastels meeting the require-
Coordinates
ments be identical nor of uniform excellence in all respects.
D4236 Practice for Labeling Art Materials for Chronic
Variations in manufacture, not covered by this specification,
Health Hazards
may cause some artists to prefer one brand to another, either of
D4303 Test Methods for Lightfastness of Colorants Used in
which may be acceptable under this specification.
Artists’ Materials
E284 Terminology of Appearance 4.3 Variation in test results can be due to differences in
G24 Practice for Conducting Exposures to Daylight Filtered pigment manufacture from time to time by a company, differ-
Through Glass ent properties of a pigment from company to company,
different combinations of pigments and other ingredients,
specimenpreparation,thicknessofpastelonsubstrate,different
instrumentsandinstrumentalreadings,variationsinthesurface
This test method is under the jurisdiction of ASTM Committee D01 on Paint
and Related Coatings, Materials, andApplications and is the direct responsibility of
of the specimen, and the conditions of exposure.Allowance for
Subcommittee D01.57 on Artist Paints and Related Materials.
thesevariationsismadebyestablishinglightfastnesscategories
Current edition approved June 1, 2020. Published June 2020. DOI: 10.1520/
that include a range of color differences.
D8330-20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
4.4 Since a specific pastel may be unusually sensitive to
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
some aspect of simulated daylight accelerated lightfastness
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. testing and show a change in color that would not occur in a
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D8330 − 20
normal home or gallery environment, two types of exposure 6.3 The pastel shall not crumble or break excessively when
are required, both natural daylight and simulated daylight. used with pressure sufficient to apply the color smoothly.
4.5 Some variation in test results is to be expected even
7. Specimen Preparation and Exposure
when the same type of exposure is repeated. Therefore, after
7.1 Materials:
triplicate specimens are exposed in each of the two types of
7.1.1 Soft, Medium, Hard Pastel Sticks, Pastel Pencils—
exposures, the lightfastness category of the pastel by each
Materials to be tested.
exposure method is based on the mean of the color change of
7.1.2 Substrate—White, uncoated, neutral pH, buffered
the three specimens, or two specimens if an outlier is dis-
100 % cotton watercolor paper or board without any optical
carded.
brighteners. Sanded pastel papers may be used that conform to
4.6 If the two methods place the pastel in the same light-
the watercolor paper or board criteria.
fastness category, the pastel is assigned to that category. If the
7.2 Preparation of Test Specimens:
pastel is placed in different lightfastness categories by the two
7.2.1 Prepare ten specimens of each pastel or stick to be
methods, either the pastel is placed in the poorer of the two
tested. For each specimen the substrate used is cut into a size
categories or a retest is conducted using the test method that
that fits the holder to be used for exposure. Draw a square 28
yielded the poorer lightfastness category. The lightfastness
1 1
by28mm(1 ⁄8by1 ⁄8in.)inthecenterofeachsubstrate.Leave
category by that test method is based on the mean of the color
enough white substrate around each specimen so that the
change of the specimens in both the original and retest that had
colored portion will not be damaged by handling or instrument
not been discarded as outliers.
mounting hardware. Using constant pressure, apply pastel to
each substrate evenly and firmly. Repeat as necessary to
5. Labeling Requirements
completely cover the square drawn on the substrate.
5.1 Provide with the Product:
7.2.1.1 Burnish each sample with the back of a stainless
5.1.1 Company or brand name; company assigned identifi-
steel spoon and reapply a final coat of pastel to the substrate.
cation number for the pastel, or company assigned color name
7.3 Color Measurement Prior to Exposure:
for the pastel, or both; however, pigment names shall not be
7.3.1 Prior to conducting the measurements described in
used as pastel names unless the pastel contains only that
7.3.2, examine the sample to assure that pastel from an
pigment, or a variant of that pigment, or that pigment and
adjoining sample has not cross-contaminated a neighboring
white; otherwise the word “Hue” must be added to the name.
pastel. Remove any contaminants and reapply as described in
5.1.2 Lightfastness Category indicated by the symbols I, II,
7.2.1.
III, IV, or V. Only pastels in Lightfastness Categories I and II
7.3.2 Color measurements are made using either a
conform with this specification.
spectrophotometer, spectrocolorimeter, or colorimeter set to
5.2 Provide on Package Label or in Literature, or Both:
use Illuminant D65 and the 1964 10° observer and excluding
5.2.1 Name and address of manufacturer, importer, or sup-
specular reflection from the measurement.The color difference
plier;
among the ten replicate specimens and the uniformity of color
5.2.2 Country of origin; and on each specimen shall be <3 CIELAB units. Color differences
5.2.3 The Colour Index name and Constitution Number of among specimens can be determined using a 25 mm viewing
port on the color measurement device. For color uniformity
every pigment in each pastel.
across the colored area, use a 10 mm or smaller viewing port.
5.3 Toxicity—All products and labeling must conform to the
If the color difference among specimens or non-uniformity
Federal Hazardous Substances Act and to Practice D4236.
across the specimen exceeds two CIELAB units, apply more
5.4 Statement of Conformance—“Conforms to ASTM
colortothespecimensasneededuntiltheymeettheuniformity
Specification D8330,” or “Conforms to ASTM D8330.,” This
requirement.
statement may be combined with other conformance
7.3.2.1 When using a 25 mm viewing port, make three
statements, such as, “Conforms to the quality and health
measurements. After each measurement, lift, partially rotate
requirements of ASTM Specification D8330 and Practice
the specimen, and reposition in the viewing port for the next
D4236.”
measurement. Find the mean of these measurements in
CIELAB units and record it as the value for the unexposed
6. Quality Assurance for Artists’ Pastels specimen.
7.3.2.2 When using an instrument with a 10 mm or smaller
6.1 Conditions Not Covered in This Specification that Affect
measuring port, make five measurements. After each
Pastels:
measurement, lift, partially rotate the specimen, and reposition
6.1.1 Substrate—The effective pH of the paper used may
in the measuring port for the next measurement. Find the mean
affect the long-term color appearance of the applied pastel.
of these measurements in CIELAB units and record it as the
6.1.2 Additives—Materials added to achieve appropriate
value for the unexposed specimen.
consistency, prevent microbial deterioration, and control appli-
cation may affect results. NOTE 1—It is difficult to achieve an even coating of the color with
complete hiding of the substrate. If the pastel does not completely hide the
6.2 Pastels shall be capable of applying an even coating of
substrate, measurement will vary from spot to spot. If the coating has
color without scratch marks. varying thicknesses, the specimen will fade unevenly. In these cases the
D8330 − 20
complete colored area may have to be measured to get a measurement that 1260 MJ⁄m can be divided into three or more phases and the device
represents the average color of the specimen. If a 25 mm (1 in.) diameter programmed to stop at the end of each phase so the color can be measured
instrument measuring port is used, the whole colored surface of the and recorded. The specimens are then returned to the test chamber and
specimen is measured; if a smaller measuring port is used, additional exposure is continued until the specified radiant exposure is reached.
measurements of different portions of the colored surface of the specimen
7.4.4.5 The uninsulated black panel temperature shall be
are necessary to accurately represent the color.
63 6 2°C. For the equivalent insulated black panel
7.4 Exposure:
temperature, consult the manufacturer of the device.
7.4.1 Three specimens of each color shall be exposed to
NOTE4—Thesetpointisthetargetconditionforthecontrolsensorwith
glass filtered solar radiation using MethodA. In addition, three
the exact number specified programmed by the user. The operational
specimens shall be exposed in a xenon-arc device operating
fluctuation given with the set point does not imply that the user is allowed
with window glass filters using Method B or C. One specimen
to program a set point higher or lower than the exact set point specified.
of each color shall be retained for visual comparison with test The operational fluctuation specified is the maximum deviation allowable
from the set point of the sensor at the control point during equilibrium
specimens following exposure, and three specimens shall be
conditions. If the operational fluctuations are greater than the maximum
retained for use in a third exposure, if needed.
allowable after the equipment has stabilized, discontinue the test and
7.4.2 Store the retained, unexposed specimens in the dark.
correct the cause of the problem before continuing.
7.4.3 TestMethodA—ExposuretoNaturalDaylightFiltered
7.4.5 Test Method C—Exposure simulating daylight filtered
through Glass:
through window glass in a humidity controlled xenon-arc
7.4.3.1 Follow Practice G24 and expose specimens during
device—This environment will typically have higher relative
themonthsfromSeptemberthroughMayinanArizonatestsite
humidity than Method B:
intheweatheringindustrydefined“openbox”sampleexposure
7.4.5.1 Follow section 7.4.4.
container that is covered with standard window glass with the
7.4.5.2 Mount specimens in unbacked holders and follow
minimum distance between the sample and the glass. With the
section 7.4.4.2. It is recommended that all unused spaces in the
“open box” positioned at a 45° angle to the horizontal, expose
specimen exposure area be filled with blank metal panels that
thespecimenstoatotalglobalsolar(290to2500nm)radiation
are not highly reflective.
dose of 1260 MJ/m incident on the glass.
7.4.5.3 Follow section 7.4.4.3.
7.4.4 Test Method B—Exposure to Xenon-Arc Radiation
7.4.5.4 Follow section 7.4.4.4.
Simulating Daylight Filtered Through Window Glass:
7.4.5.5 Set the relative humidity at the control point in the
7.4.4.1 Use a xenon-arc device that conforms to the require-
test chamber to 50 6 10 % RH.
ments defined in Practices G151 and G155. Unless otherwise
7.4.5.6 In machines that allow control of chamber air
specified, the spectral power distribution of the xenon-arc
temperature, it shall be set at 43°C and maintained at 62°C.
deviceshallconformtotherequirementsinPracticesG151and
NOTE 5—It has been found that Alizarin Crimson and other pigments
G155 for xenon arc radiation through a window glass filter.
are affected differently when exposed to a light/dark cycle rather than to
7.4.4.2 Place specimens in the test device in positions that
continuous light. Dark periods are characteristic of both outdoor and
conformwithirradianceuniformityspecifiedinPracticesG151
indoor exposures. Therefore, using a xenon arc machine, when mutually
agreed on, the following light/dark cycle
...