ASTM C1248-22

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Designation: C1248 − 18 C1248 − 22
Standard Test Method for
Staining of Porous Substrate by Joint Sealants
This standard is issued under the fixed designation C1248; 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
1.1 This test method covers four types of laboratory tests to determine if a joint sealant has a probability of staining a porous
substrate (such as marble, limestone, sandstone, and granite). granite, or other similar material). The tests are on compressed
samples and include (1) storage under standard laboratory conditions, (2) storage in an oven, and (3) exposure in a fluorescent
UV/condensation device, and (4) exposure in a xenon arc device.
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. after
SI units are provided for information only and are not considered standard.
1.3 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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.4 The committee with jurisdiction over this standard is not aware of any comparable standards published by other organizations.
This standard is similar, but not identical, to ISO 16938-1.
1.5 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.
2. Referenced Documents
2.1 ASTM Standards:
C717 Terminology of Building Seals and Sealants
C920 Specification for Elastomeric Joint Sealants
C1442 Practice for Conducting Tests on Sealants Using Artificial Weathering Apparatus
G113 Terminology Relating to Natural and Artificial Weathering Tests of Nonmetallic Materials
G151 Practice for Exposing Nonmetallic Materials in Accelerated Test Devices that Use Laboratory Light Sources
G154 Practice for Operating Fluorescent Ultraviolet (UV) Lamp Apparatus for Exposure of Nonmetallic Materials
G155 Practice for Operating Xenon Arc Lamp Apparatus for Exposure of Materials
2.2 ISO Standard:
ISO 16938-1 Buildings and civil engineering works — Determination of the staining of porous substrates by sealants used in
joints — Part 1: Test with compression
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 June 1, 2018July 1, 2022. Published June 2018August 2022. Originally approved in 1993. Last previous edition approved in 20122018 as
C1248-08(2012).C1248-18. DOI: 10.1520/C1248-18.10.1520/C1248-22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from International Organization for Standardization (ISO), ISO Central Secretariat, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva, Switzerland,
https://www.iso.org.
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3. Terminology
3.1 Definitions:
3.1.1 Refer to Terminology C717 and G113 for definitions of terms used in this test method.
4. Summary of Test Method
4.1 In this test method standard joint specimens are compressed and clamped at the manufacturer’s rated movement capability and
subjected to the following treatments; (a) four of the specimens are stored at standard conditions while under compression for up
to 28 days; (b) four of the specimens are exposed in an oven while under compression for up to 28 days; (c) four of the specimens
are exposed either in a fluorescent UV/condensation device or in a xenon arc device while under compression for up to 28 days.
4.1.1 This test method allows for additional exposure beyond the minimum 28 day exposure period as described in 4.1. If it is
desired to extend the exposure period beyond 28 days, prepare an additional six specimens for each extended exposure period. Of
these six specimens prepared, two specimens each should be stored as described in the three conditions named in 4.1.
4.2 The effects of the test are evaluated by visual inspection for changes in surface appearance and average measurements of any
stain depth and stain width.
4.3 This test method is applicable to any type of elastomeric joint sealant and any type of porous substrate.
5. Significance and Use
5.1 Staining of building materials is an aesthetically undesirable occurrence. This test method evaluates the likelihood of a sealant
causing an early stain on a porous substrate due to exudation of materials from the sealant. Since this is an accelerated test, it does
not necessarily predict that the tested sealants will not stain or discolor porous substrates over longer periods of time.
6. Apparatus
6.1 Forced-Draft Oven.
6.2 Exposure Apparatus:
6.2.1 Fluorescent UV/condensation apparatus that conforms to the requirements in Practices G151 and G154 with UVA-340 type
lamps.
6.2.2 Xenon-Arc apparatus that conforms to the requirements in Practices G151 and G155 with daylight type filters.
6.3 TFE-FluorocarbonCasting Spacers.
6.4 Masking Tape.
7. Test Specimens
7.1 Substrates shall be 25 mm by 25 mm by 75 mm (1 by 1 by 3(0.98 in. by 0.98 in. by 2.95 in.). A total of 24 substrates substrate
pieces are required to make the twelve test specimens.
7.1.1 If testing beyond the minimum 28 day exposure period, prepare an additional twelve substrates to make the six additional
test specimens as required in 4.1.1.
NOTE 1—The precision and bias statement is based on Vermont white marble and Bethel white granite substrates.
7.2 Primers—When a primer is recommended by the sealant manufacturer, apply the primer to one substrate block of each test
specimen. Apply the primer where the sealant will be in contact with the substrate.
7.3 Preparation of Test Specimens:
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7.3.1 Multi-Component Sealants—Prepare twelve test specimens for each substrate that is to be used in the test. After maintaining
the unopened sample for at least 24 h at standard conditions, mix thoroughly for 5 min at least 250 g of base compound with the
1 1
appropriate amount of curing agent. Apply a bead of sealant 13 mm by 13 mm by 50 mm ((0.51 ⁄2 in. by ⁄20.51 in. by 21.97 in.)
between parallel 25 mm by 75 mm (1 (0.98 in. by 32.95 in.) faces of substrates (see Fig. 1). Use appropriate casting 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 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 finishedbeing over-applied onto the top surface.
Remove the tape immediately following filling of the specimen joint cavity.
7.3.2 Single-Component Sealants—Prepare the specimens as described in 7.3.1 except that no mixing is required. Condition the
sealed cartridge or bulk container at standard conditions for at least 24 h before use.
FIG. 1 Stain Test Specimen
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8. Conditioning
8.1 Cure specimens for 21 days at standard conditions.
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