|Description / Abstract
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|This test method covers a procedure for evaluating the pull-off
strength (commonly referred to as adhesion) of a coating system
from metal substrates. Pull-off strength of coatings from concrete
is described in Test Method D7234. The test determines either the
greatest perpendicular force (in tension) that a surface area can
bear before a plug of material is detached, or whether the surface
remains intact at a prescribed force (pass/fail). Failure will
occur along the weakest plane within the system comprised of the
test fixture, adhesive, coating system, and substrate, and will be
exposed by the fracture surface. This test method maximizes tensile
stress as compared to the shear stress applied by other methods,
such as scratch or knife adhesion, and results may not be
NOTE 1—The procedure in this standard was developed for metal
substrates, but may be appropriate for other rigid substrates such
as plastic and wood. Factors such as loading rate and flexibility
of the substrate must be addressed by the user/specifier.
Pull-off strength measurements depend upon both material and
instrumental parameters. Results obtained by each test method may
give different results. Results should only be assessed for each
test method and not be compared with other instruments. There are
five instrument types, identified as Test Methods B-F. It is
imperative to identify the test method used when reporting
NOTE 2—Method A, which appeared in previous versions of this
standard, has been eliminated as its main use is for testing on
concrete substrates (see Test Method D7234).
This test method uses a class of apparatus known as portable
pull-off adhesion testers.2 They are capable of applying
a concentric load and counter load to a single surface so that
coatings can be tested even though only one side is accessible.
Measurements are limited by the strength of adhesion bonds between
the loading fixture and the specimen surface or the cohesive
strengths of the adhesive, coating layers, and substrate.
This test can be destructive and spot repairs may be
The values stated in MPa (inch-pound) units are to be regarded
as the standard. The values given in parentheses are for
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 and
health practices and determine the applicability of regulatory
limitations prior to use.
2 The term adhesion tester may be somewhat of a
misnomer, but its adoption by two manufacturers and at least two
patents indicates continued usage.
*A Summary of Changes section appears at the end of this
|Additional Supplemental Documents