ASTM C679-15(2022)

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: C679 − 15 (Reapproved 2022)
Standard Test Method for
Tack-Free Time of Elastomeric Sealants
This standard is issued under the fixed designation C679; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope 3. Terminology
1.1 This test method covers a procedure for the determina- 3.1 Definitions—See Terminology C717 for definitions of
tion of the tack-free time property of single- and multi- the following terms used in this test method: caulking,
component elastomeric sealants commonly used for sealing, compound, cure, elastomeric, glazing, non-sag sealant, sealant,
caulking, and glazing in buildings and related construction. self-leveling sealant, and standard conditions.
1.2 This test method is applicable to self-leveling and
4. Summary of Test Method
non-sag grades of sealant. Sealants requiring slight heating to
4.1 Thetestconsistsoflightlytouchingasurfaceofacuring
facilitate extrusion from the cartridge or gun are also described
sealant with a polyethylene film at regular intervals until the
by this test method.
sealant does not attach itself to the film and the film appears
NOTE 1—See Specification C920 for type and grade definitions.
clean when peeled from the surface.
1.3 The values stated in SI units are to be regarded as
4.2 More specifically a strip of polyethylene film is placed
standard. The values given in parentheses after SI units are
on the surface of the curing sealant and a 30 g (1.06-oz) weight
provided for information only and are not considered standard.
is placed on the film. The weight is left in place for 30 s, then
1.4 This standard does not purport to address all of the
removed and the polyethylene strip is removed and examined
safety concerns, if any, associated with its use. It is the
for sealant attachment to the film. The length of time from
responsibility of the user of this standard to establish appro-
when the sealant was first applied and tooled into the template
priate safety, health, and environmental practices and deter-
until the time the sealant is no longer picked up by the film is
mine the applicability of regulatory limitations prior to use.
called tack-free time.
NOTE 2—Currently, there is no ISO standard similar to this specifica-
4.3 With some sealants, interpretation of the end point is
tion.
confusing in that a very thin film of sealant or oil will transfer
1.5 This international standard was developed in accor-
to the film. For consistency of data, record the point where the
dance with internationally recognized principles on standard-
bulksealantisnolongertransferredtotheplasticbutignorethe
ization established in the Decision on Principles for the
very thin uniform film of sealant or the plasticizer transferred
Development of International Standards, Guides and Recom-
to the plastic test strip.
mendations issued by the World Trade Organization Technical
5. Significance and Use
Barriers to Trade (TBT) Committee.
5.1 The tack-free time is a measure of the surface cure time
2. Referenced Documents
and may generally be correlated to a variety of useful param-
2.1 ASTM Standards:
eters such as the time interval before the sealant (1) resists
C717 Terminology of Building Seals and Sealants damage by touch or light surface contact, (2) resists job-site or
C920 Specification for Elastomeric Joint Sealants
airborne dirt pick-up, (3) resists impinging rainfall.
5.2 The tack-free time is sometimes used as an on-the-job
quality assurance test. A quality product that is consistent and
ThistestmethodisunderthejurisdictionofASTMCommitteeC24onBuilding
reproducible will generally fall within a maximum and mini-
Seals and Sealants and is the direct responsibility of Subcommittee C24.20 on
General Test Methods.
mum tack-free time.
Current edition approved Jan. 1, 2022. Published January 2022. Originally
5.3 This test for tack-free time can be used at any tempera-
approved in 1971. Last previous edition approved in 2015 as C679 – 15. DOI:
10.1520/C0679-15R22.
ture and humidity. It is important that if a sealant will be used
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
in a climate quite different than the standard conditions called
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
out in this test method, then those conditions be used to test the
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. sealant.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C679 − 15 (2022)
6. Apparatus oughly mix 250 g of the base compound with the appropriate
amount of curing agent following the manufacturer’s mixing
6.1 Cabinet or Room, capable of maintaining Standard
instructions.
Conditions.
8.3 Prepare at least two specimens for each sealant as
6.2 Weight, rectangular, with dimensions of 41 mm by
follows: Center the template on the metal plate and carefully
5 3
19 mm (1 ⁄8 in. long by ⁄4 in. wide) and mass of 30 g (1.06 oz).
fill it with sealant avoiding air pockets. Strike off the surface
NOTE 3—The thickness of the weight should be approximately 6 mm
flat using a metal straightedge, to a uniform thickness.
( ⁄4 in.) but planed to a thickness that will provide the 30 g (1.06-oz) mass.
8.4 Relative Tack-Free Time Unknown. If the relative tack-
6.3 Polyethylene Strips, several (often 6 or more), clear, low
free time is unknown, the procedure is to pretest one of the test
density with dimensions 127 mm by 25 mm by 0.15 mm (5 in.
specimens by lightly touching the surface of the sealant with a
by 1 in. by 0.006 in.).
film of polyethylene wrapped over the end of a finger. Touch
6.4 Timer, capable of measuring minutes and hours.
the test piece in accordance with an appropriate time interval
described in 8.5. Try to touch a different place on the surface
6.5 Rectangular Plates, several (often 6 or more),
each time. After the polyethylene wrapped finger is lightly
rectangular, approximately 152 mm by 76 mm (6 in. by 3 in.),
touched to the surface of the sealant, it is immediately removed
made of non-porous material such as tin plated steel or
and examined to see if sealant was picked up on th
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