ASTM D660-93(2005)
(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
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.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D660 – 93 (Reapproved 2005)
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 Department of Defense.
1. Scope 4.1.5 Mosaic Type—Checking in which the breaks in the
surface of the film form straight sided, geometric patterns
1.1 The illustrated reference standards included in this test
which join on all sides.
method are representative of degrees and types of checking of
4.1.6 Shrinkage Type—Checking in which the breaks in the
exterior paint films. These standards are primarily intended for
surface of the film usually form individual short breaks with
comparative evaluation.
shorter irregular breaks progressing at right angles.
2. Terminology
4.1.7 Short, Random Type—Checking in which breaks in
the surface of the film form short, irregular patterns. These
2.1 Definitions of Terms Specific to This Standard:
breaks are usually individual and do not join.
2.1.1 checking, n—that phenomenon manifested in paint
4.1.8 Sigmoid Type—Checking in which the breaks in the
films by slight breaks in the film that do not penetrate through
surface of the film form oval patterns. These oval shapes rarely
the last applied coating.
complete their circle.
2.1.1.1 Discussion—Where precision is necessary in evalu-
ating a paint film, checking may be described as visible (as
5. Use of Illustrated Reference Standards
seen with the naked eye) or as microscopic (as observed under
5.1 The use of the reference standards shown in Fig. 1
a magnification up to ten diameters).
requires the following precautions:
3. Significance and Use 5.1.1 Since the type and degree of failure may vary over any
given area, a representative portion should be rated. It is
3.1 Since checking is not easily recognizable, this test
recommended that ratings be made at several locations, noting
method is intended to provide, through definition and illustra-
types and degree of failure.
tions, a means of evaluating the degree of this film failure.
5.1.2 Care must be taken to recognize that several types of
4. Types of Checking
checking may be present on the same surface.
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 a
4.1.1 Irregular Pattern Type—Checking in which the
moderately soft brush. Care must be taken not to damage the
breaks develop in the surface of the film in no definite pattern.
finish.
4.1.2 Line and Short Parallel Type—Checking in which the
5.1.4 Fig. 2 illustrates microscopic checking under 10-
breaks in the surface of the film are generally arranged in
diameter magnification.
parallel lines.
5.1.5 For convenience in recording the data obtained, the
4.1.3 Switch Type—Checking in which the breaks in the
records should be kept on forms agreed upon between
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