ASTM D772-86(1993)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 772 – 86 (Reapproved 1993)
Standard Test Method for
Evaluating Degree of Flaking (Scaling) of Exterior Paints
This standard is issued under the fixed designation D 772; 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 (e) 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 this test method and are provided in the Pictorial Standards of
Coating Defects Handbook are representative of the degree of
1.1 This test method covers the evaluation of the degree of
cracking of exterior paint films. Fig. 1 is for illustration
flaking (scaling) of exterior paints by comparison with photo-
purposes only and should not be used for evaluation.
graphic standards.
6.2 The use of the photographic reference standards illus-
2. Referenced Documents
trated in Fig. 1 requires the following precautions:
6.2.1 Care must be taken not to confuse various types of
2.1 ASTM Standards:
failure that may be present on the same surface.
D 1150 Single and MultiPanel Forms for Recording Results
6.2.2 It must be realized that degree of failure will vary over
of Exposure Tests of Paints
any given area. Therefore, an average portion of the film
2.2 Other Standards:
should be used for comparison. On larger surfaces it is
Pictorial Standards of Coating Defects Handbook
recommended that ratings be made at several locations and the
3. Terminology Definition
mean and range reported.
6.2.3 In technical literature, a distinction is sometimes made
3.1 flaking (scaling)—that phenomenon manifested in paint
between flaking and scaling. In most cases, however, flaking
films by the actual detachment of pieces of the film itself either
and scaling refer to the same phenomenon. In some instances,
from its substrate or from paint previously applied. Flaking
the term flaking is used to describe the detachment of pieces of
(scaling) is generally preceded by cracking or checking or
film less than ⁄4 in. (6.4 mm) in size, and scaling, the
blistering, and is the result of loss of adhesion, usually due to
detachment of pieces over ⁄4 in. in size. In other instances, the
stress-strain factors coming into play.
term flaking is used to describe the detachment of pieces of
4. Significance and Use
film from the immediate undercoat (intercoat failure) and
scaling the detachment of pieces from the base (complete
4.1 Flaking (scaling) failure of paint films can occur in use.
failure). It should be kept in mind that the flakes may vary
This test method provides a means of evaluating the degree of
widely in size and shape from those illustrated by the reference
failure by comparing to pictorial standards.
standards in Fig. 1, varying from a fraction of an inch to several
5. Type of Flaking (Scaling)
inches in size.
6.2.4 Peeling is frequently due to a moisture condition and
5.1 Only one type of flaking (scaling) is recogni
...