ASTM C1248-93(1998)
(Test Method)Standard Test Method for Staining of Porous Substrate by Joint Sealants
Standard Test Method for Staining of Porous Substrate by Joint Sealants
SCOPE
1.1 This test method covers an accelerated laboratory procedure to determine if a joint sealant has a probability of staining a porous substrate (such as marble, limestone, sandstone, and granite).
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.3 This standard does not purport to address all of the safety problems, 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.
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Designation: C 1248 – 93 (Reapproved 1998)
Standard Test Method for
Staining of Porous Substrate by Joint Sealants
This standard is issued under the fixed designation C 1248; 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 of the specimens are exposed in an ultraviolet (UV) fluorescent
test chamber while under compression for up to 28 days.
1.1 This test method covers an accelerated laboratory pro-
4.2 The effects of the test are evaluated by visual inspection
cedure to determine if a joint sealant has a probability of
for changes in surface appearance and average measurements
staining a porous substrate (such as marble, limestone, sand-
of any stain depth and stain width.
stone, and granite).
4.3 This test method is applicable to any type of elastomeric
1.2 The values stated in SI units are to be regarded as the
joint sealant and any type of porous substrate.
standard. The values given in parentheses are for information
only.
5. Significance and Use
1.3 This standard does not purport to address all of the
5.1 Staining of building materials is an aesthetically unde-
safety problems, if any, associated with its use. It is the
sirable occurrence. This test method evaluates the likelihood of
responsibility of the user of this standard to establish appro-
a sealant causing an early stain on a porous substrate due to
priate safety and health practices and determine the applica-
exudation of materials from the sealant. Since this is an
bility of regulatory limitations prior to use.
accelerated test, it does not necessarily predict that the tested
2. Referenced Documents sealants will not stain or discolor porous substrates over longer
periods of time.
2.1 ASTM Standards:
C 717 Terminology of Building Seals and Sealants
6. Apparatus
G 53 Practice for Operating Light- and Water-Exposure
6.1 Forced-Draft Oven.
Apparatus (Fluorescent UV-Condensation Type) for Expo-
3 6.2 Ultraviolet Chamber, conforming to Practice G 53 and
sure of Non-Metallic Materials
UVA 340 type bulbs.
3. Terminology 6.3 “C” Clamps, or other device for maintaining the speci-
men under compression.
3.1 Definitions:
6.4 TFE-Fluorocarbon Spacers.
3.1.1 Refer to Terminology C 717 for definitions of the
6.5 Masking Tape.
following terms used in this test method: bead; compound;
cure; elastomer; joint; primer; sealant; self leveling sealant;
7. Test Specimens
and substrate.
7.1 Substrates shall be 25 by 25 by 75 mm (1 by 1 by 3 in.).
4. Summary of Test Method A total of 24 substrates are required to make the twelve test
specimens.
4.1 This test method consists of subjecting standard joint
specimens to various exposure treatments as follows: ( a) all
NOTE 1—The precision and bias statement is based on Vermont white
specimens are compressed and clamped at the manufacturer’s
marble and Bethel white granite substrates.
rated movement capability; (b) one-third of the specimens are
7.2 Primers—When a primer is recommended by the seal-
stored at standard conditions while under compression for up to
ant manufacturer, apply the primer to one substrate block of
28 days; (c) one-third of the specimens are exposed in an oven
each test specimen. Apply the primer where the sealant will be
while under compression for up to 28 days; and (d) one-third
in contact with the substrate.
7.3 Preparation of Test Specimens:
7.3.1 Standard conditions of temperature and relative hu-
midity used throughout this test method are defined as 23 6
This test method is under the jurisdiction of ASTM Committee C-24 on
Building Seals and Sealants and is the direct responsibility of Subcommittee C24.40
2°C (73.4 6 3.6°F) and 50 6 5 %, respectively.
on Weathering.
7.3.2 Multi-Component Sealants—Prepare twelve test
Current edition approved Sept. 15, 1993. Published November 1993.
specimens for each substrate that is to be used in the test. After
Annual Book of ASTM Standards, Vol 04.07.
Annual Book of ASTM Standards, Vol 14.02. maintaining the unopened sample for at least 24 h at standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C 1248 – 93 (1998)
conditions, mix thoroughly for 5 min at least 250 g of base
compound with the appropriate amount of curing agent. Apply
1 1
a bead of sealant 13 by 13 by 50 mm ( ⁄2 by ⁄2 by 2 in.)
between parallel 25 by 75 mm (1 by 3 in.) faces of substrates
(see Fig. 1). Use appropriate spacers to form the proper size
bead. Use adhesive tape, rubber bands, or clamps to hold the
test specimen together before and after filling it with the
sealant. In the case of a self leveling sealant, use masking or
other suitable tape to retain the sealant. Use masking tape on
the top surface of substrates to prevent sealant from curing on
the finished surface. Remove the tape immediately following
filling of the specimen joint cavity.
7.3.3 Single-Component Sealants—Prepare the specimens
as described in 7.3.2 except that no mixing is required.
Condition the sealed cartridge or bulk container at standard
conditions for at least 24 h before use.
8. Conditioning
8.1 Cure specimens for 21 days at standard conditions.
Separate the TFE-fluorocarbon spacers from the sealant as
soon as practical during the curing period without damaging
the sealant.
FIG. 2 Staining Test Report Form
NOTE 2—Th
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