ASTM C1257-94

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: C 1257 – 94
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 local pollutants. This test method is used to determine the
relative weathering performance of a sealant against an unex-
1.1 This test method provides an accelerated procedure for
posed control or a reference material for which the outdoor
predicting the effects of ultraviolet light, heat, and moisture
weathering characteristics are known.
exposure on color, chalking, cracking, and adhesion of solvent-
5.2 This test method is conducted using aluminum channels.
release sealants.
Other substrate materials may show different results.
1.2 The values stated in SI units are to be regarded as the
standard. The values given in parentheses are for information
6. Apparatus
only.
6.1 Fluorescent UV and Condensation Apparatus, comply-
1.3 This standard does not purport to address all of the
ing with Practice G 53.
safety concerns, if any, associated with its use. It is the
6.1.1 The UV light source shall be UVA-340 fluorescent
responsibility of the user of this standard to establish appro-
lamps as described in 6.2 of Practice G 53.
priate safety and health practices and determine the applica-
6.2 Four-Mill Finish Aluminum U-Channels, 76 mm long
bility of regulatory limitations prior to use.
3 3
by 19 mm wide by 9.5 mm deep (3 by ⁄4 by ⁄8 in.) inside
2. Referenced Documents dimensions. Additional substrate materials may be specified.
6.3 Steel Spatula.
2.1 ASTM Standards:
C 717 Terminology of Building Seals and Sealants
7. Procedure
G 53 Practice for Operating Light and Water Exposure
7.1 Condition sufficient compound in an original closed
Apparatus (Fluorescent UV-Condensation Type) for Expo-
3 container for at least 24 h at standard conditions. Standard
sure of Nonmetallic Materials
conditions are to be a temperature of 23 6 2°C (73 6 3.6°F)
3. Terminology and relative humidity of 50 6 5%.
7.2 Prepare four sealant test specimens in aluminum
3.1 Definitions—Definitions of the following terms are
U-channels.
found in Terminology C 717: adhesive failure (adhesion loss),
7.2.1 Thoroughly clean channels using a suitable solvent
compound, cure, sealant, solvent-release sealant, substrate.
such as methyl ethyl ketone (MEK). Allow to dry before filling
4. Summary of Test Method
with sealant.
7.2.2 Block the ends of the U-channels with masking tape
4.1 The test specimens are prepared in U-shaped aluminum
and overfill the entire channel with conditioned compound
channels. After curing, the specimens are exposed to alternat-
from the bottom up being careful to avoid air entrapment.
ing cycles of ultraviolet light at elevated temperature and
Strike the channel off flat with a spatula. Do not remove the
condensing humidity at elevated temperature. At the end of the
masking tape. It is to stay in place for the entire test. Removing
exposure period, the specimens are examined for chalking,
it may disturb the uncured or cured sealant.
color change, center cracking, edge cracking, and loss of
7.3 Cure the test specimens at standard conditions for 21
adhesion versus an unexposed control sample.
days.
5. Significance and Use
NOTE 1—The producer may request conditions other than those speci-
5.1 It is difficult to establish a precise correlation between
fied in 7.3 for the curing period, provided they meet the following
accelerated and natural weathering because of geographical requirements: the curing period must extend for 21 days, and the
temperature during the curing period shall not exceed 70°C (158°F).
climatic variations, local weather variation from normal, and
7.4 After the curing period, place three of the specimens in
the weathering apparatus. The sealant surface shall be facing
This test method is under the jurisdiction of ASTM Committee C-24 on
Building Seals and Sealants and is the direct responsibility of Subcommittee C24.18
on Solvent Release Sealants.
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.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
C 1257
the inside of the chamber. Attach the specimens to the sample 8.1.5 Variations, if any, from the specified test procedure.
holder such that the open or top surface of the channel is in
contact with
...