ASTM G24-97

Standard Practice for Conducting Exposures to Daylight Filtered Through Glass

SCOPE
1.1 This practice evaluates the resistance of nonmetallic materials to solar radiation filtered through glass.  
1.2 This practice is limited to the method of conducting the exposures. The preparation of test specimens and evaluation of results are covered in various standards for the specific materials.  
1.3 This practice includes two methods:  
1.3.1 Method A -Continuous exposure under glass in a cabinet with passive ventilation.  
1.3.2 Method B -Continuous exposure under glass in enclosed black-painted cabinet (black box under glass).  
1.4 The values stated in SI units are to be regarded as the standard.  
1.5 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.

General Information

• Status: Historical
• Publication Date: 09-Jul-1997
• ICS: 59.080.01 - Textiles in general
• Technical Committee: G03 - Weathering and Durability
• Drafting Committee: G03.02 - Natural and Environmental Exposure Tests

Relations

• Replaced By: ASTM G24-05 - Standard Practice for Conducting Exposures to Daylight Filtered Through Glass
• Effective Date: 01-Jan-2005
• Referred By: ASTM D1435-20 - Standard Practice for Outdoor Weathering of Plastics
• Effective Date: 10-Jul-1997
• Referred By: ASTM G183-15(2023) - Standard Practice for Field Use of Pyranometers, Pyrheliometers and UV Radiometers
• Effective Date: 10-Jul-1997
• Referred By: ASTM G90-23 - Standard Practice for Performing Accelerated Outdoor Weathering of Materials Using Concentrated Natural Sunlight
• Effective Date: 10-Jul-1997
• Referred By: ASTM D4303-10(2022) - Standard Test Methods for Lightfastness of Colorants Used in Artists' Materials
• Effective Date: 10-Jul-1997
• Referred By: ASTM D4364-13(2022)e1 - Standard Practice for Performing Outdoor Accelerated Weathering Tests of Plastics Using Concentrated Sunlight
• Effective Date: 10-Jul-1997
• Referred By: ASTM G141-09(2021) - Standard Guide for Addressing Variability in Exposure Testing of Nonmetallic Materials
• Effective Date: 10-Jul-1997
• Referred By: ASTM G201-16 - Standard Practice for Conducting Exposures in Outdoor Glass-Covered Exposure Apparatus with Air Circulation
• Effective Date: 10-Jul-1997
• Referred By: ASTM D6901-15(2021) - Standard Specification for Artists' Colored Pencils
• Effective Date: 10-Jul-1997
• Referred By: ASTM G7/G7M-21 - Standard Practice for Natural Weathering of Materials
• Effective Date: 10-Jul-1997
• Referred By: ASTM G178-16(2023) - Standard Practice for Determining the Activation Spectrum of a Material (Wavelength Sensitivity to an Exposure Source) Using the Sharp Cut-On Filter or Spectrographic Technique
• Effective Date: 10-Jul-1997
• Referred By: ASTM G156-17 - Standard Practice for Selecting and Characterizing Weathering Reference Materials
• Effective Date: 10-Jul-1997
• Referred By: ASTM G147-17 - Standard Practice for Conditioning and Handling of Nonmetallic Materials for Natural and Artificial Weathering Tests
• Effective Date: 10-Jul-1997
• Referred By: ASTM D8330-20 - Standard Specification for Artists’ Pastels
• Effective Date: 10-Jul-1997
• Referred By: ASTM C1589/C1589M-18(2023) - Standard Practice for Outdoor Weathering of Construction Seals and Sealants
• Effective Date: 10-Jul-1997

Standards Content (Sample)

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:G24–97
Standard Practice for
Conducting Exposures to Daylight Filtered Through Glass
ThisstandardisissuedunderthefixeddesignationG 24;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope G 113 Terminology Relating to Natural and Artificial
Weathering Tests of Nonmetallic Materials
1.1 This practice evaluates the resistance of nonmetallic
2.2 Other Documents:
materials to solar radiation filtered through glass.
WMO Guide to Meteorological Instruments and Methods of
1.2 This practice is limited to the method of conducting the
Observation WMO No. 8, Fifth Edition.
exposures.The preparation of test specimens and evaluation of
ISO 105 B01 Textiles—Tests for Colour Fastness, Interna-
results are covered in various standards for the specific
tional Standards Organization, Geneva, Switzerland.
materials.
ISO 877 Plastics—Methods of Exposure to Direct Weath-
1.3 Exposure conducted according to this practice can use
ering,toWeatheringUsingGlass-FilteredDaylight,andto
two types of exposure cabinets.
IntensifiedWeatheringbyDaylightUsingFresnelMirrors,
1.3.1 Type A—A cabinet that allows passive ventilation of
International Standards Organization, Geneva, Switzer-
specimens being exposed behind glass.
land
1.3.2 Type B—Enclosed cabinet with exterior painted black
AATCC 16C Colorfastness to Light, Daylight
that allows no ventilation of specimens exposed behind glass.
Exposures conducted using a Type B cabinet are typically
3. Terminology
referred to as “black box under glass exposures”.
3.1 Definitions:
1.4 This practice is technically similar to Method B of
3.1.1 The definitions contained in Terminology G 113 are
ISO 877.
applicable to this practice.
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4. Significance and Use
responsibility of the user of this standard to establish appro-
4.1 Since solar irradiance, air temperature, relative humid-
priate safety and health practices and determine the applica-
ity, and the amount and kind of atmospheric contaminants vary
bility of regulatory limitations prior to use.
continuously, results from exposures based on time may differ.
2. Referenced Documents The variations in the results may be minimized by timing the
exposures in terms of one or more environmental parameters
2.1 ASTM Standards:
such as solar radiant exposure, or in terms of a predetermined
E 782 Practice for Exposure of Cover Materials for Solar
property change of a reference specimen with known perfor-
Collectors to Natural Weathering under Conditions Simu-
2 mance.
lating Operational Mode
4.2 Moisture combined with atmospheric contaminants may
E 824 MethodforTransferofCalibrationfromReferenceto
2 produce degradation effects as great as those produced by solar
Field Pyranometers
irradiance. This may explain differences in rankings of speci-
E 903 Test Method for SolarAbsorptance, Reflectance, and
2 mens exposed to equivalent solar radiant exposure when other
Transmittance of Materials Using Integrating Spheres
environmental conditions vary.
G 84 Practice for Measurement of Time-of-Wetness on
SurfacesExposedtoWettingConditionsasinAtmospheric
Corrosion Testing
This practice is under the jurisdiction of ASTM Committee G-3 on Durability
of Nonmetallic Materials and is the direct responsibility of Subcommittee G 03.02 Annual Book of ASTM Standards, Vol 14.02.
on Natural Environmental Testing. Available from World Meteorological Organization, Geneva, Switzerland.
Current edition approved July 10, 1997. Published October 1997. Originally Available from American National Standards Institute, 11 W. 42nd St., 13th
published as G 24 – 73. Last previous edition G 24 – 73 (1980). Floor, New York, NY 10036.
2 7
Annual Book of ASTM Standards, Vol 12.02. American Association of Textile Chemists and Colorists, Research Triangle
Annual Book of ASTM Standards, Vol 03.02. Park, PO Box 12215, NC 27709-2215.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
G24
4.3 Since the method of mounting may influence the tem- vary by as much as 300 %. In addition, exposures conducted
perature and other parameters of the specimen during expo- at different times of the year can cause large differences in rate
sure, there should be a mutual understanding as to the method of degradation.
ofmountingthespecimenfortheparticularexposuretestunder 4.5 In order to minimize differences in 300 to 340 nm UV
consideration. transmission caused by rapid solarization of new glass, this
FIG. 1 a and 1b Typical Well-Ventilated Under Glass Exposure Cabinet, Type A
practice requires that glass be pre-aged for three months prior
to use in exposure cabinets.
4.6 DifferencesinUVtransmissionbetweendifferentlotsof
glass persist after solarization. The largest differences in UV
transmission of glass are between 300 and 320 nm. Use of
radiantexposurebasedontotalsolarradiationortotalsolarUV
radiationtodetermineexposureperiodsisnotsensitivetothese
differences. For materials very sensitive to differences in short
wavelength UV radiation, monitoring UVB radiation behind
glass may be the best approach for use when radiant energy is
used to determine the length of exposures. However, for
materials sensitive to long wavelength UV or visible radiation,
monitoring UVB radiation or using reference materials that are
very sensitive to short wavelength solar ultraviolet radiation to
determine exposure periods may produce inconsistent results.
FIG. 2 Typical Enclosed Under Glass Exposure Cabinet, Type B
4.7 This practice is best used to compare the relative
(Black Box Under Glass)
performance of materials tested at the same time behind the
same lot of glass. Because of variability between lots of glass
andbetweenexposuresconductedatdifferenttimesoftheyear,
4.4 There can be large differences in 300 to 350 nm UV
comparing the amount of degradation in materials exposed for
transmission of single strength window glass. For example, at the same duration or radiant exposure at separate times, or in
separate fixtures using different lots of glass is not recom-
320 nm, the percent transmission for seven different lots of
mended. This practice should not be used to establish “pass/
single strength window glass ranged from 8.4 to 26.8 %. For
fail” approval of materials after a specific period of exposure
this range of transmission, the rate of degradation for materials
sensitive to short wavelength UV from 300 to 320 nm could
Ketola,W.D.,andRobbins,J.S.“UVTransmissionofSingleStrengthWindow
Glass”, Accelerated and Outdoor Durability Testing of Organic Materials, ASTM
STP 1202, Warren D. Ketola and Douglass Grossman, Eds, American Society for
Testing and Materials, Philadelphia, 1993.
Crewdson, L. F., and Bahadur-Singh, C., “A Review of the Variability
EncounteredWhen Exposure Materials to Glass Filtered Sunlight”, Accelerated and
Outdoor Durability Testing of Organic Materials, ASTM STP 1202, Warren D.
Ketola and Douglass Grossman, Eds, American Society for Testing and Materials,
Philadelphia, 1993.
G24
different requirements for glass transmittance and do not require pre-
unless performance comparisons are made relative to a control
aging.
material exposed simultaneously, or the variability in the test is
quantified so that statistically significant pass/fail judgments
5.1.3.2 After the three month pre-exposure period, it is
can be made.
recommended that the spectral transmittance of representative
4.8 It is strongly recommended that at least one control
samples from each lot of glass be measured. Typically, “single
material be exposed with each test.The control material should
strength” glass will have a transmittance of 10 to 20 % at 320
be of similar composition and construction and be chosen so
nm and at least 85 % at wavelengths of 380 nm or higher after
that its degradation mechanisms or failure modes are the same
the three month pre-aging procedure. If transmittance of the
as that of the material being tested. It is preferable to use two
glass is measured, report the average for at least three pieces of
control materials, one with relatively good durability, and one
the lot of glass being tested. Follow the instructions for
with relatively poor durability. If control materials are included
measurement of transmittance of solid samples recommended
as part of the test, they shall be used for the purpose of
by the manufacturer of the UV-visible spectrophotometer used.
comparing the performance of the test materials relative to the
If a spectrophotometer with an integrating sphere is used, the
controls.
measurements shall be performed in accordance with Test
4.9 There are other standards which describe exposures to
Method E 903.
glass filtered daylight. Three cited standards are ISO 105-B01,
NOTE 3—After the initial pre-aging period, the UV transmission of
ISO 877, and AATCC 16C.
window glass is suitable for at least 60 months of use. UV transmission
4.10 Because of the possibility that certain materials may
differences between lots of glass persist during this time, however.
outgas during exposure, it is recommended that only similar
5.1.3.3 Wash the exterior surface and the interior surface of
materials be exposed in the same under glass cabinet.
the glass cover monthly (or more frequently, if required) to
remove dust particles and other undesirable material.
5. Apparatus
NOTE 4—Different pieces of single-strength window glass can have
5.1 Exposure Cabinet:
different optical properties even if purchased from the same manufacturer.
5.1.1 Type A—Exposures shall be conducted in a glass-
5.1.4 The enclosure or cabinet shall be equipped with a rack
covered enclosure or cabinet of any convenient size. It shall be
which supports the specimens in a plane parallel to the glass
constructed of wood, metal, or other satisfactory material, in
cover at a distance of not less than 75 mm (3 in.). The
order to protect the specimens from rain and weather, and shall
mounting frame or plate shall be constructed of a material that
be open on the back or sides to allow ambient air to circulate
is compatible with the test specimens. In order to minimize
over the specimens (Fig. 1a and b).
shadowing from the top and sides of the cabinet, the usable
5.1.2 Type B (Black Box Under Glass)—Exposures shall be
exposure area under the glass shall be limited to that of the
conducted in a glass-covered enclosure or cabinet of any
glass cover reduced by twice the distance from the cover to the
convenient size. It shall be constructed of corrosion resistant
specimens. Three types of mounting
...