ASTM D2370-16(2021)

Standard Test Method for Tensile Properties of Organic Coatings

SIGNIFICANCE AND USE
5.1 Tensile properties determined by this method are of value in studying the behavior of coatings subjected to environmental stresses, such as those produced by aging and weathering. (See Refs. (1-10).)4  
5.2 Tensile properties may vary with specimen thickness, method of preparation, gage length, rate of load application, tensile tester response, and type of grips used. Consequently, where precise comparative results are desired, these factors must be carefully controlled.
SCOPE
1.1 This test method covers the determination of the elongation, tensile strength, and stiffness (modulus of elasticity) of organic coatings when tested as free films.  
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to inch-pound units that 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 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.

General Information

• Status: Published
• Publication Date: 31-Oct-2021
• ICS: 25.220.60 - Organic coatings
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.23 - Physical Properties of Applied Paint Films

Relations

• Refers: ASTM D4708-24 - Standard Practice for Preparation of Uniform Free Films of Organic Coatings
• Effective Date: 15-Jan-2024
• Refers: ASTM D1005-95(2020) - Standard Test Method for Measurement of Dry-Film Thickness of Organic Coatings Using Micrometers
• Effective Date: 01-Jun-2020
• Refers: ASTM D4708-19 - Standard Practice for Preparation of Uniform Free Films of Organic Coatings
• Effective Date: 01-Mar-2019
• Refers: ASTM D823-17 - Standard Practices for Producing Films of Uniform Thickness of Paint, Varnish, and Related Products on Test Panels
• Effective Date: 01-Dec-2017
• Refers: ASTM D823-95(2012) - Standard Practices for Producing Films of Uniform Thickness of Paint, Varnish, and Related Products on Test Panels
• Effective Date: 01-Nov-2012
• Refers: ASTM D4708-12 - Standard Practice for Preparation of Uniform Free Films of Organic Coatings
• Effective Date: 01-Jul-2012
• Refers: ASTM D882-09 - Standard Test Method for Tensile Properties of Thin Plastic Sheeting
• Effective Date: 01-Jan-2009
• Refers: ASTM D4708-07 - Standard Practice for Preparation of Uniform Free Films of Organic Coatings
• Effective Date: 01-Nov-2007
• Refers: ASTM D1005-95(2007) - Standard Test Method for Measurement of Dry-Film Thickness of Organic Coatings Using Micrometers
• Effective Date: 01-Nov-2007
• Refers: ASTM D823-95(2007) - Standard Practices for Producing Films of Uniform Thickness of Paint, Varnish, and Related Products on Test Panels
• Effective Date: 01-Jun-2007
• Refers: ASTM D4708-99(2004) - Standard Practice for Preparation of Uniform Free Films of Organic Coatings
• Effective Date: 01-Jun-2004
• Refers: ASTM D882-02 - Standard Test Method for Tensile Properties of Thin Plastic Sheeting
• Effective Date: 10-Apr-2002
• Refers: ASTM D882-00 - Standard Test Method for Tensile Properties of Thin Plastic Sheeting
• Effective Date: 10-Apr-2002
• Refers: ASTM D882-01 - Standard Test Method for Tensile Properties of Thin Plastic Sheeting
• Effective Date: 10-Apr-2002
• Refers: ASTM D823-95(2001) - Standard Practices for Producing Films of Uniform Thickness of Paint, Varnish, and Related Products on Test Panels
• Effective Date: 01-Jan-2001

Overview

ASTM D2370-16(2021): Standard Test Method for Tensile Properties of Organic Coatings is an internationally recognized procedure developed by ASTM for determining the tensile properties of organic coatings when tested as free films. This test method covers the measurement of critical mechanical properties such as elongation, tensile strength, and modulus of elasticity (stiffness). These properties are essential for assessing how coatings will perform under mechanical and environmental stress, including exposure to weathering and aging.

The standard provides uniform guidance to manufacturers, laboratories, and quality assurance professionals for preparing specimens, conducting tests, and reporting findings. ASTM D2370 is referenced by regulators and is valuable in both product development and quality control for organic coatings.

Key Topics

• Tensile Strength: Measures the maximum load a free film coating can withstand before breaking.
• Elongation at Break: Indicates the ability of the coating to stretch before rupture, reflecting flexibility.
• Modulus of Elasticity (Stiffness): Assesses the coating’s resistance to deformation under stress and its ability to recover original shape.
• Specimen Preparation: Details proper conditioning, recommended thickness, and the use of practices like ASTM D4708 for consistent free film production.
• Testing Method: Utilizes a tensile tester with controlled gage lengths, rates of elongation, and specific environmental conditioning to ensure repeatable and comparable results.
• Precision and Accuracy: Highlights the need for controlling variables like specimen thickness, gage length, and test environment to obtain valid comparative data.

Applications

ASTM D2370 is widely used in various industries for the evaluation of organic coatings such as paints, varnishes, and protective finishes. Key applications include:

• Product Development: Characterizing the mechanical properties of new or modified coatings to predict performance and optimize formulations.
• Quality Control: Monitoring batch-to-batch consistency of coatings to meet specified requirements and regulatory standards.
• Weatherability Studies: Assessing the durability and flexibility of coatings following exposure to accelerated or natural aging and environmental stresses.
• Material Certification: Supporting claims of product performance in technical datasheets and compliance documents.
• Comparative Testing: Benchmarking coating systems from different suppliers or after process modifications for performance validation.

By following the ASTM D2370 test method, organizations can ensure that data regarding tensile strength, elongation, and stiffness of organic coatings are reliable, valid, and comparable worldwide.

Related Standards

ASTM D2370 references and is often used alongside these related standards:

• ASTM D4708: Practice for Preparation of Uniform Free Films of Organic Coatings.
• ASTM D823: Practices for Producing Films of Uniform Thickness of Paint, Coatings, and Related Products on Test Panels.
• ASTM D882: Test Method for Tensile Properties of Thin Plastic Sheeting.
• ASTM D1005: Test Method for Measurement of Dry-Film Thickness of Organic Coatings Using Micrometers.
• ASTM D3980: Practice for Interlaboratory Testing of Paint and Related Materials (Withdrawn but historically relevant).

Practical Value

Implementing ASTM D2370-16(2021) enables manufacturers and laboratories to objectively evaluate and specify the mechanical properties of coatings, leading to improved product reliability and customer confidence. The standard supports international trade by establishing clear, reproducible test procedures acknowledged by the World Trade Organization Technical Barriers to Trade (TBT) Committee. By standardizing tensile property testing, ASTM D2370 enhances product durability, safety, and marketability in the global coatings industry.

Keywords: ASTM D2370, tensile properties, organic coatings, tensile strength, elongation at break, modulus of elasticity, free films, coatings testing, mechanical properties, quality control, standard test method.

Standards Content (Sample)

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: D2370 − 16 (Reapproved 2021)
Standard Test Method for
Tensile Properties of Organic Coatings
This standard is issued under the fixed designation D2370; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber 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 D4708Practice for Preparation of Uniform Free Films of
Organic Coatings
1.1 This test method covers the determination of the
elongation, tensile strength, and stiffness (modulus of elastic-
3. Terminology
ity) of organic coatings when tested as free films.
3.1 Definitions of Terms Specific to This Standard:
1.2 The values stated in SI units are to be regarded as
3.1.1 elongation at break, n—the increase in specimen
standard. The values given in parentheses are mathematical
length from the point of initial load application to the point of
conversions to inch-pound units that are provided for informa-
film rupture in a tension test.
tion only and are not considered standard.
3.1.2 gage length, n—the initial length of the test specimen
1.3 This standard does not purport to address all of the
between the jaws of the tensile tester.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 3.1.3 stiffness (modulus of elasticity), n—the load per unit
priate safety, health, and environmental practices and deter-
arearequiredtoelongatethefilm1%fromthefirstpointinthe
mine the applicability of regulatory limitations prior to use. stress-strain curve where the slope becomes constant.
1.4 This international standard was developed in accor-
3.1.4 stress-strain curve, n—the curve resulting from a plot
dance with internationally recognized principles on standard-
of tensile load against the distance of jaw separation (elonga-
ization established in the Decision on Principles for the
tion of specimen).
Development of International Standards, Guides and Recom-
3.1.5 tensile strength (nominal), n—the load per original
mendations issued by the World Trade Organization Technical
unit area at which a specimen fails or yields in a tension (pull)
Barriers to Trade (TBT) Committee.
test.
2. Referenced Documents
4. Summary of Test Method
2.1 ASTM Standards:
4.1 Free unsupported films of the materials to be tested are
D823Practices for Producing Films of Uniform Thickness
prepared in accordance with Practice D4708. The tensile
of Paint, Coatings and Related Products on Test Panels
propertiesofthefreefilmsaredeterminedbymeansofatensile
D882Test Method for Tensile Properties of Thin Plastic
testing apparatus.
Sheeting
D1005Test Method for Measurement of Dry-Film Thick-
5. Significance and Use
ness of Organic Coatings Using Micrometers
D3980Practice for Interlaboratory Testing of Paint and
5.1 Tensile properties determined by this method are of
Related Materials (Withdrawn 1998)
value in studying the behavior of coatings subjected to envi-
ronmental stresses, such as those produced by aging and
weathering. (See Refs. (1-10).)
This test method is under the jurisdiction of ASTM Committee D01 on Paint
5.2 Tensile properties may vary with specimen thickness,
and Related Coatings, Materials, andApplications and is the direct responsibility of
method of preparation, gage length, rate of load application,
Subcommittee D01.23 on Physical Properties of Applied Paint Films.
Current edition approved Nov. 1, 2021. Published November 2021. Originally
tensile tester response, and type of grips used. Consequently,
approved in 1965. Last previous edition approved in 2016 as D2370–16. DOI:
where precise comparative results are desired, these factors
10.1520/D2370-16R21.
must be carefully controlled.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
3 4
The last approved version of this historical standard is referenced on Boldfacenumbersinparenthesesrefertothelistofreferencesattheendofthis
www.astm.org. standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2370 − 16 (2021)
6. Apparatus specimen to 60.1 µm (0.04 mil) with a micrometer in
accordance with Test Method D1005, taking five measure-
6.1 Equipment for applying films of uniform thickness as
ments within the gage length area. If a video-extensometer is
described in Practices D823.
used,applymarkingsonthesamplewithinthedistanceofgage
6.2 Micrometer Film Thickness Gage as described in Test
length selected. The markings on the sample must be readable
Method D1005.
by the instrument being used. These will vary between manu-
facturer and models. The material and method of making the
6.3 Tensile Testeroftheconstantrateofjawseparationtype,
equipped with load cells having capacities of 1 to 50 N (0.2 to marks must not affect the characteristics of the sample.
10 lb), and equipped with computer with tester controlling
10.3 Set the jaw separation of the tensile tester at the gage
software, or optionally an indicating device such as an elec-
length selected. Place the test specimen in the grips of the
tronic constant speed chart recorder, a digital device that
testing machine, taking care to align the long axis of the
displays numerical values, or a printer that records the numeri-
specimen with an imaginary line joining the points of attach-
cal values. Tensile tester can also be equipped with a video-
ment of the grips to the machine. Tighten the grips evenly and
extensometer and environmental chamber, when higher accu-
firmly to the degree necessary to minimize slipping of the
racy of test is required and testing is conducted at an elevated
specimen during test.
or low temperature.
NOTE 1—Mounting is facilitated by the use of air activated jaws.
6.4 Precision Specimen Cutterhavingadoublebladewitha
Line-type jaws will minimize slippage and breakage. The application of
foot to hold the sample in place or other suitable sharp cutter
pressure-sensitive cloth to the ends of the film can improve jaw grip.
blade.
Specialself-tighteninggripsdesignedtobeusedwiththinfilmscouldalso
be used.
7. Test Specimens
10.4 Selectamutuallyagreeduponrateofelongation(strain
7.1 The test specimens shall be free films having a width
rate) that is in the range of 5 to 100%⁄min. Set the crosshead
thatisbetween13and25mm( ⁄2and1in.).Nospecimenshall
speed of the tensile tester to provide this rate for the gage
vary by more than 62% in width along its entire gage length.
length chosen.
The length shall be at least 50 mm (2 in.) longer than the gage
NOTE 2—A rate of elongation should be selected that is optimum for
length selected for the test.
testing the types of materials to be evaluated. For relatively brittle films,
elongationratesof5to20%aresuggested.Forrelativelyextensiblefilms,
7.2 Prepare free films by one of the procedures described in
elongation rates of 50 to 100% are suggested. (Refer to Test Method
Practice D4708.
D882 for relation of elongation rate to elongation at break.)
8. Calibration
10.5 Elongate the test specimen until rupture of the film
occurs and evaluate the stress-strain curve as follows:
8.1 Balance, zero, and calibrate the load weighing and
10.5.1 Determine the specimen elongation from video-
recording system of the tensile tester in accordance with
extensometer data or by measuring the increase in jaw sepa-
methods specified by the manufacturer.
rationfromthepointoforiginalloadapplicationtothepointof
8.2 If video-extensometer is used, calibrate instrument ac-
rupture.
cording to manufacturer’s instructions.
10.5.2 Measure the tensile pull in Newtons (lb) required to
rupture the film.
9. Conditioning
10.5.3 If stiffness is desired, determine the tensile stress in
9.1 Specimens must be fully dried and cured before testing
MPa to elongate the film 1% from the first point in the
according to manufacturer specification.
...