ASTM C1257-94(2000)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: C 1257 – 94 (Reapproved 2000)
Standard Test Method for
Accelerated Weathering of Solvent-Release-Type Sealants
This standard is issued under the fixed designation C 1257; 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 climatic variations, local weather variation from normal, and
local pollutants. This test method is used to determine the
1.1 This test method provides an accelerated procedure for
relative weathering performance of a sealant against an unex-
predicting the effects of ultraviolet light, heat, and moisture
posed control or a reference material for which the outdoor
exposure on color, chalking, cracking, and adhesion of solvent-
weathering characteristics are known.
release sealants.
5.2 This test method is conducted using aluminum channels.
1.2 The values stated in SI units are to be regarded as the
Other substrate materials may show different results.
standard. The values given in parentheses are for information
only.
6. Apparatus
1.3 This standard does not purport to address all of the
6.1 Fluorescent UV and Condensation Apparatus, comply-
safety concerns, if any, associated with its use. It is the
ing with Practice G 53.
responsibility of the user of this standard to establish appro-
6.1.1 The UV light source shall be UVA-340 fluorescent
priate safety and health practices and determine the applica-
lamps as described in 6.2 of Practice G 53.
bility of regulatory limitations prior to use.
6.2 Four-Mill Finish Aluminum U-Channels, 76 mm long
3 3
2. Referenced Documents by 19 mm wide by 9.5 mm deep (3 by ⁄4 by ⁄8 in.) inside
dimensions. Additional substrate materials may be specified.
2.1 ASTM Standards:
6.3 Steel Spatula.
C 717 Terminology of Building Seals and Sealants
G 53 Practice for Operating Light and Water Exposure
7. Procedure
Apparatus (Fluorescent UV-Condensation Type) for Expo-
3 7.1 Condition sufficient compound in an original closed
sure of Nonmetallic Materials
container for at least 24 h at standard conditions. Standard
3. Terminology conditions are to be a temperature of 23 6 2°C (73 6 3.6°F)
and relative humidity of 50 6 5%.
3.1 Definitions—Definitions of the following terms are
7.2 Prepare four sealant test specimens in aluminum
found in Terminology C 717: adhesive failure (adhesion loss),
U-channels.
compound, cure, sealant, solvent-release sealant, substrate.
7.2.1 Thoroughly clean channels using a suitable solvent
4. Summary of Test Method such as methyl ethyl ketone (MEK). Allow to dry before filling
with sealant.
4.1 The test specimens are prepared in U-shaped aluminum
7.2.2 Block the ends of the U-channels with masking tape
channels. After curing, the specimens are exposed to alternat-
and overfill the entire channel with conditioned compound
ing cycles of ultraviolet light at elevated temperature and
from the bottom up being careful to avoid air entrapment.
condensing humidity at elevated temperature. At the end of the
Strike the channel off flat with a spatula. Do not remove the
exposure period, the specimens are examined for chalking,
masking tape. It is to stay in place for the entire test. Removing
color change, center cracking, edge cracking, and loss of
it may disturb the uncured or cured sealant.
adhesion versus an unexposed control sample.
7.3 Cure the test specimens at standard conditions for 21
5. Significance and Use
days.
5.1 It is difficult to establish a precise correlation between
NOTE 1—The producer may request conditions other than those speci-
accelerated and natural weathering because of geographical
fied in 7.3 for the curing period, provided they meet the following
requirements: the curing period must extend for 21 days, and the
temperature during the curing period shall not exceed 70°C (158°F).
This test method is under the jurisdiction of ASTM Committee C24 on Building
Seals and Sealants and is the direct responsibility of Subcommittee C24.40 on
Weathering.
Current edition approved Jan. 15, 1994. Published April 1994. Apparatus and lamps from Q-Panel Co., 26200 First St., Cleveland, Ohio
Annual Book of ASTM Standards, Vol 04.07. 44145; and Atlas Electric Devices Co., 4114 N. Ravenswood Ave., Chicago, IL
Annual Book of ASTM Standards, Vol 14.02. 60613, have been found satisfactory.
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C 1257 – 94 (2000)
7.4 After the curing period, place three of the specimens in it can be determined if the cracking or adhesion loss was the
the weathering apparatus. The sealant surface shall be facing sole result of exposure.
the inside of the chamber. Attach the specimens to the sample 8.1.5 Variations, if any, from t
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