ASTM D660-93(2019)
(Test Method)Standard Test Method for Evaluating Degree of Checking of Exterior Paints
Standard Test Method for Evaluating Degree of Checking of Exterior Paints
SIGNIFICANCE AND USE
3.1 Since checking is not easily recognizable, this test method is intended to provide, through definition and illustrations, a means of evaluating the degree of this film failure.
SCOPE
1.1 The illustrated reference standards included in this test method are representative of degrees and types of checking of exterior paint films. These standards are primarily intended for comparative evaluation.
1.2 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
Relations
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: D660 − 93 (Reapproved 2019)
Standard Test Method for
Evaluating Degree of Checking of Exterior Paints
This standard is issued under the fixed designation D660; 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 4.1.3 Switch Type—Checking in which the breaks in the
surface of the film form short and long irregular lines crossing
1.1 The illustrated reference standards included in this test
each other in a wire brushed pattern.
method are representative of degrees and types of checking of
4.1.4 Crow Foot Type—Checking in which the breaks in the
exterior paint films. These standards are primarily intended for
surface of the film form in a definite three-pronged pattern with
comparative evaluation.
the breaks running from a center and forming an angle of about
1.2 This international standard was developed in accor-
120° between the prongs.
dance with internationally recognized principles on standard-
4.1.5 Mosaic Type—Checking in which the breaks in the
ization established in the Decision on Principles for the
surface of the film form straight sided, geometric patterns
Development of International Standards, Guides and Recom-
which join on all sides.
mendations issued by the World Trade Organization Technical
4.1.6 Shrinkage Type—Checking in which the breaks in the
Barriers to Trade (TBT) Committee.
surface of the film usually form individual short breaks with
shorter irregular breaks progressing at right angles.
2. Terminology
4.1.7 Short, Random Type—Checking in which breaks in the
2.1 Definitions of Terms Specific to This Standard:
surface of the film form short, irregular patterns. These breaks
2.1.1 checking, n—that phenomenon manifested in paint
are usually individual and do not join.
films by slight breaks in the film that do not penetrate through
4.1.8 Sigmoid Type—Checking in which the breaks in the
the last applied coating.
surface of the film form oval patterns. These oval shapes rarely
2.1.1.1 Discussion—Where precision is necessary in evalu-
complete their circle.
ating a paint film, checking may be described as visible (as
seen with the naked eye) or as microscopic (as observed under 5. Use of Illustrated Reference Standards
a magnification up to ten diameters).
5.1 The use of the reference standards shown in Fig. 1
requires the following precautions:
3. Significance and Use
5.1.1 Since the type and degree of failure may vary over any
3.1 Since checking is not easily recognizable, this test
given area, a representative portion should be rated. It is
method is intended to provide, through definition and
recommended that ratings be made at several locations, noting
illustrations, a means of evaluating the degree of this film
types and degree of failure.
failure.
5.1.2 Care must be taken to recognize that several types of
checking may be present on the same surface.
4. Types of Checking
5.1.3 Paint films may collect excessive quantities of dirt,
4.1 Many types of checking are recognized, of which some
which may mask the type and degree of failure. If necessary,
are:
dirt should be removed by careful and gentle brushing with
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