ASTM C1257-15(2023)

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: C1257 − 15 (Reapproved 2023)
Standard Test Method for
Accelerated Weathering of Solvent-Release-Type Sealants
This standard is issued under the fixed designation C1257; 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 Lamp Apparatus for Exposure of Materials
G155 Practice for Operating Xenon Arc Lamp Apparatus for
1.1 This test method includes two laboratory accelerated
Exposure of Materials
exposure procedures for predicting the effects of ultraviolet or
ultraviolet/visible radiation, heat, and moisture on color,
3. Terminology
chalking, cracking, and adhesion of solvent-release sealants.
3.1 Definitions:
1.2 The values stated in SI units are to be regarded as the
3.1.1 Refer to Terminology C717 and G113 for definitions
standard. The values given in parentheses are for information
of terms used in this test method: standard conditions.
only.
4. Summary of Test Method
1.3 The committee with jurisdiction over this standard is not
aware of any comparable standards published by other orga-
4.1 Four test specimens are prepared in U-shaped aluminum
nizations.
channels. After curing, three of the specimens are exposed in
1.4 This standard does not purport to address all of the the laboratory accelerated weathering device and the fourth
safety concerns, if any, associated with its use. It is the specimen is stored under standard conditions as an unexposed
responsibility of the user of this standard to establish appro- file specimen. At the end of the exposure period, the specimens
priate safety, health, and environmental practices and deter- are examined for chalking, color change, center cracking, edge
mine the applicability of regulatory limitations prior to use. cracking, and loss of adhesion versus the unexposed file
1.5 This international standard was developed in accor- specimen.
dance with internationally recognized principles on standard-
5. Significance and Use
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
5.1 It is difficult to establish a precise correlation between
mendations issued by the World Trade Organization Technical
laboratory accelerated and natural weathering because of (1)
Barriers to Trade (TBT) Committee.
geographical climatic variations, local weather variation from
normal, and local pollutants and (2) the fact that the accelera-
2. Referenced Documents
tion factor is material dependent, varying with the type of
2.1 ASTM Standards: material as well as its formulation. This test method is used to
C717 Terminology of Building Seals and Sealants determine the resistance of a sealant to laboratory accelerated
C1442 Practice for Conducting Tests on Sealants Using weathering and, if a control material with known outdoor
Artificial Weathering Apparatus weathering performance is used, the relative weathering per-
G113 Terminology Relating to Natural and Artificial Weath- formance of the sealant against that of the control material.
ering Tests of Nonmetallic Materials
5.2 This test method is conducted using aluminum channels.
G151 Practice for Exposing Nonmetallic Materials in Accel-
Other substrate materials may show different results.
erated Test Devices that Use Laboratory Light Sources
G154 Practice for Operating Fluorescent Ultraviolet (UV)
6. Apparatus
6.1 Exposure Apparatus:
6.1.1 Fluorescent UV/Condensation Apparatus, that con-
This test method is under the jurisdiction of ASTM Committee C24 on Building
forms to the requirements in Practices G151 and G154 with
Seals and Sealants and is the direct responsibility of Subcommittee C24.40 on
Weathering.
UVA-340 type lamps.
Current edition approved June 1, 2023. Published July 2023. Originally approved
6.1.2 Xenon-Arc Apparatus, that conforms to the require-
in 1994. Last previous edition approved in 2015 as C1257 – 15. DOI: 10.1520/
ments in Practices G151 and G155 with daylight type filters.
C1257-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
6.2 Four-Mill Finish Aluminum U-Channels, 76 mm long
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
3 3
by 19 mm wide by 9.5 mm deep (3 by ⁄4 by ⁄8 in.) inside
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. dimensions. Additional substrate materials may be specified.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1257 − 15 (2023)
6.3 Steel Spatula. faces the light source. Keep the fourth test specimen as an
unexposed file specimen of the test material and store at
7. Procedure
standard conditions.
7.4.1 Procedure for Fluorescent UV/Condensation
7.1 Condition sufficient compound in an original closed
Apparatus—Operate the device in accordance with the proce-
container for at least 24 h at standard conditions.
dure in Section 7.3 of Practice C1442. Remove the specimens
7.2 Prepare four sealant test specimens in aluminum
from the apparatus after a minimum of 1000 h of exposure.
U-channels.
7.4.2 Procedure for Xenon-Arc Apparatus—Operate the de-
7.2.1 Thoroughly clean channels using a suitable solvent
vice in accordance with the procedure in Section 7.2 of
such as methyl ethyl ketone (MEK). Allow to dry before filling
Practice C1442. When operated at the preferred irradiance
with sealant.
level of 0.51 W(m · nm) at 340 nm, remove the specimens
7.2.2 Block the ends of the U-channels with masking tape
from the apparatus after a minimum of 1000 h (1835 kJ/(m ·
and overfill the entire channel with conditioned compound
nm) at 340 nm). See Annex A1 in C1442 for determining the
from the bottom up being careful to avoid air entrapment.
...