ASTM C461-23

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Designation: C461 − 17 C461 − 23
Standard Test Methods for
Mastics and Coatings Used With Thermal Insulation
This standard is issued under the fixed designation C461; 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 These test methods cover procedures for sampling and testing mastics and coatings for use as weather and vapor barrierretarder
finishes on thermal insulations and for other accessory use.
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
1.3 The test methods appear in the following order:
Section
Sampling 4
Uniformity and Storage Stability 5
Stability Under Freezing 6
Density and Weight per Gallon 7
Consistency 8
Solids Content 9
Content of Volume Solids and Coverage of Mastics and 10
Coatings
Sag Resistance (Build) 11
Drying Time 12
Flash Point 13
1.4 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 and health practices and determine the applicability of regulatory
limitations prior to use.
1.4 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.
1.5 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.
These test methods are under the jurisdiction of ASTM Committee C16 on Thermal Insulation and are the direct responsibility of Subcommittee C16.33 on Insulation
Finishes and Moisture.
Current edition approved Sept. 1, 2017Sept. 1, 2023. Published September 2017September 2023. Originally approved in 1960. Last previous edition approved in 20152017
as C461 – 81 (2015). DOI: 10.1520/C0461-17.17. DOI: 10.1520/C0461-23.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C461 − 23
2. Referenced Documents
2.1 ASTM Standards:
C168 Terminology Relating to Thermal Insulation
C419 Practice for Making and Curing Test Specimens of Mastic Thermal Insulation Coatings
D56 Test Method for Flash Point by Tag Closed Cup Tester
D71 Test Method for Relative Density of Solid Pitch and Asphalt (Displacement Method)
D93 Test Methods for Flash Point by Pensky-Martens Closed Cup Tester
D140 Practice for Sampling Asphalt Materials
D1475 Test Method for Density of Liquid Coatings, Inks, and Related Products
D2196 Test Methods for Rheological Properties of Non-Newtonian Materials by Rotational Viscometer
D2369 Test Method for Volatile Content of Coatings
D3278 Test Methods for Flash Point of Liquids by Small Scale Closed-Cup Apparatus
3. Terminology
3.1 Definitions—For definitions of terms used in these test methods, see Terminology C168.
4. Sampling
4.1 Prior to opening or sampling, or both, any mastic or coating, its Safety Data Sheet (SDS) shall be reviewed to ensure
appropriate precautions or personal protective equipment, or both, are utilized.
4.2 Take the samples for laboratory examination from the original containers immediately after stirring to a uniform condition.
Determine the number of containers sampled as required to represent a shipment in accordance with Practice D140. Restir the
composite sample immediately before taking out portions for individual tests.
5. Uniformity and Storage Stability
5.1 Open the original containers and examine them for uniformity of contents. Record the degree of separation, if any, into
portions of appreciably different consistency, such as thick or thin layers, sedimentation or coagulation, etc., also of difficulty
encountered in stirring to a uniform condition.
5.2 Examine the contents of a full container of not less than 1 qt (1 L) that has stood undisturbed for 48 h. Make notation of any
separation of solvent or water, coagulation, or settlement of suspended matter, that cannot be overcome by moderate agitation.
5.3 Additionally, if required, examine and report the condition in the container after 3 months’ storage, examining for uniformity
in accordance with 5.1.
6. Stability Under Freezing
6.1 Fill a 1-pt (500-mL) press-top tin can three quarters full with the coating, and hold the filled and closed container in a chamber
at a temperature of 0 6 5°F (−18 6 3°C) for a minimum of 12 h consecutively under natural convection conditions.
6.2 At the expiration of the freezing period, permit the coating to warm to room temperature by exposure of the container to the
temperature of the laboratory for a minimum of 6 h. After the first operation of freezing and thawing, repeat the procedure twice
so that the coating will have been subjected to three cycles of freezing and thawing.
6.3 After the completion of the third cycle, open the container, and note any separation of solvent or water, coagulation, settlement
of suspended matter, or the presence of distinct layers, or a combination of these. If the compound cannot be rendered
homogeneous by moderate stirring at laboratory temperature, report that it has coagulated.
7. Density and Weight per Gallon
7.1 Apparatus:
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volume information, refer to the standard’s Document Summary page on the ASTM website.
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7.1.1 Container
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