ASTM D2794-93(2024)

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: D2794 − 93 (Reapproved 2024)
Standard Test Method for
Resistance of Organic Coatings to the Effects of Rapid
Deformation (Impact)
This standard is issued under the fixed designation D2794; 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 of Paint, Coatings and Related Products on Test Panels
D1186 Test Methods for Nondestructive Measurement of
1.1 This test method covers a procedure for rapidly deform-
Dry Film Thickness of Nonmagnetic Coatings Applied to
ing by impact a coating film and its substrate and for evaluating
a Ferrous Base (Withdrawn 2006)
the effect of such deformation.
1.2 This test method should be restricted to testing in only 3. Terminology
one laboratory when numerical values are used because of the
3.1 Definitions of Terms Specific to This Standard:
poor reproducibility of the method. Interlaboratory agreement
3.1.1 impact resistance, of a coating, n—the number of
is improved when ranking is used in place of numerical values.
inch-pounds (kilogram-metres) required to produce cracking in
1.3 The values stated in inch-pound units are to be regarded the deformed coating.
as standard. The values given in parentheses are mathematical
4. Summary of Test Method
conversions to SI units that are provided for information only
and are not considered standard.
4.1 The organic coatings under test are applied to suitable
thin metal panels. After the coatings have cured, a standard
1.4 This standard does not purport to address all of the
weight is dropped a distance so as to strike an indenter that
safety concerns, if any, associated with its use. It is the
deforms the coating and the substrate. The indentation can be
responsibility of the user of this standard to establish appro-
either an intrusion or an extrusion. By gradually increasing the
priate safety, health, and environmental practices and deter-
distance the weight drops, the point at which failure usually
mine the applicability of regulatory limitations prior to use.
occurs can be determined. Films generally fail by cracking,
1.5 This international standard was developed in accor-
which is made more visible by the use of a magnifier, by the
dance with internationally recognized principles on standard-
application of a copper sulfate (CuSO ) solution on steel, or by
ization established in the Decision on Principles for the
the use of a pin hole detector.
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
5. Significance and Use
Barriers to Trade (TBT) Committee.
5.1 Coatings attached to substrates are subjected to damag-
2. Referenced Documents
ing impacts during the manufacture of articles and their use in
2 service. In its use over many years, this test method for impact
2.1 ASTM Standards:
resistance has been found to be useful in predicting the
D609 Practice for Preparation of Cold-Rolled Steel Panels
performance of organic coatings for their ability to resist
for Testing Paint, Varnish, Conversion Coatings, and
cracking caused by impacts.
Related Coating Products
D823 Practices for Producing Films of Uniform Thickness
6. Apparatus
6.1 Tester, consisting of a vertical tube to guide a cylindrical
1 weight that is dropped on a punch resting on the test panel.
This test method is under the jurisdiction of ASTM Committee D01 on Paint
and Related Coatings, Materials, and Applications and is the direct responsibility of 6.1.1 Guide Tube, 24 in. to 48 in. (0.6 m to 1.2 m) long
Subcommittee D01.23 on Physical Properties of Applied Paint Films.
mounted vertically in a base plate. A slot is cut lengthwise on
Current edition approved Jan. 15, 2024. Published January 2024. Originally
one side of the tube to act as a guide for a cylindrical weight
approved in 1969. Last previous edition approved in 2019 as D2794 – 93 (2019).
that fits inside the tube. Graduations are marked in inch-pounds
DOI: 10.1520/D2794-93R24.
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 last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
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D2794 − 93 (2024)
along the slot. The base is constructed so that a thin flat panel evident, repeat the procedure at a greater height, increasing 1
can be inserted at 2 in. (50 mm) below the tube. in. (25 mm) at a time. Once visible cracks are observed, repeat
6.1.2 Weight, metal cylinder, made to fit inside the guide the test five times at each of three heights; slightly above,
tube. A pin is fitted into one side of the weight to act as a guide slightly below, and at that determined in the first trial. Test in
by riding in the slot of the tube and to serve as a handle by a random fashion so that all impacts from one height are not
which the weight can be raised and released and serve as the made in succession or on one panel.
indicator of inch-pounds (kilogram-metres).
10.3 Examine the impacted areas for cracking by one of the
6.2 Indenter—A steel punch with a hemispherical head following methods:
having a diameter of either 0.500 in. (12.7 mm) or 0.625 in.
10.3.1 Use a magnifier to examine the area for cracks.
(15.9 mm). The head rests on the test panel
...