ASTM D4541-22

Standard Test Method for Pull-Off Strength of Coatings Using Portable Adhesion Testers

SIGNIFICANCE AND USE
4.1 The pull-off strength of a coating is a performance property that may be referenced in specifications. This test method serves as a means for uniformly preparing and testing coated surfaces, and evaluating and reporting the results. This test method is applicable to any portable apparatus meeting the requirements for determining the pull-off strength of a coating in this standard (see Annex A1 – Annex A5).  
4.2 Variations in results with the same coating are likely when any parameter of the test is changed. This includes change in glue, load fixture size, substrate coating cure time, pull rate, environmental conditions, if the coating is scored, or using a different device. Therefore, when a series of results will be compared with one another or used for statistical analysis, the type of apparatus, substrate, test procedures, glue type, and if scoring is used should be the same for the pulls considered.4 It is recommended that these parameters and the environmental conditions allowed during the test be mutually agreed upon between the interested parties.  
4.3 The purchaser or specifier shall designate a specific test method procedure; B, C, D, E, or F and test Protocol; 1, or 2, when calling out this standard. In cases where either the Protocol or a pass/fail criterion is not designated, Protocol 1 shall be used.
SCOPE
1.1 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. This test offers two test protocols. Protocol 1 (test to fracture) determines the greatest perpendicular force (in tension) that a surface area can bear before a plug of material is detached. Protocol 2 (pass/fail) determines if the coated surface remains intact at a defined load criteria. Fracture will occur along the weakest plane within the system comprised of the test fixture, glue, 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 comparable.
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.
Note 2: The procedure in this standard was developed for use on flat surfaces. The results could have greater variability with lower values and averages for surfaces other than flat.  
1.2 Pull-off strength measurements depend upon material, instrumentation and test 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 results.
Note 3: 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).  
1.3 This test method describes 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 adhesive bonds between the loading fixture and the specimen surface or the cohesive strengths of the glue, coating layers, and substrate.  
1.4 This test can be destructive and spot repairs may be necessary.  
1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the st...

General Information

• Status: Published
• Publication Date: 30-Jun-2022
• ICS: 87.040 - Paints and varnishes
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.46 - Industrial Protective Coatings

Relations

• Refers: ASTM D3933-98(2017) - Standard Guide for Preparation of Aluminum Surfaces for Structural Adhesives Bonding (Phosphoric Acid Anodizing)
• Effective Date: 01-Nov-2017
• Refers: ASTM D2651-01(2016) - Standard Guide for Preparation of Metal Surfaces for Adhesive Bonding
• Effective Date: 01-May-2016
• Refers: ASTM E691-13 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-May-2013
• Refers: ASTM D7234-12 - Standard Test Method for Pull-Off Adhesion Strength of Coatings on Concrete Using Portable Pull-Off Adhesion Testers
• Effective Date: 01-Jul-2012
• Refers: ASTM E691-11 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2011
• Refers: ASTM D3933-98(2010) - Standard Guide for Preparation of Aluminum Surfaces for Structural Adhesives Bonding (Phosphoric Acid Anodizing)
• Effective Date: 01-Oct-2010
• Refers: ASTM E691-08 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Oct-2008
• Refers: ASTM D2651-01(2008) - Standard Guide for Preparation of Metal Surfaces for Adhesive Bonding
• Effective Date: 01-Apr-2008
• Refers: ASTM D7234-05 - Standard Test Method for Pull-Off Adhesion Strength of Coatings on Concrete Using Portable Pull-Off Adhesion Testers
• Effective Date: 01-Dec-2005
• Refers: ASTM E691-05 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2005
• Refers: ASTM D3933-98(2004) - Standard Guide for Preparation of Aluminum Surfaces for Structural Adhesives Bonding (Phosphoric Acid Anodizing)
• Effective Date: 01-Apr-2004
• Refers: ASTM D2651-01 - Standard Guide for Preparation of Metal Surfaces for Adhesive Bonding
• Effective Date: 10-Oct-2001
• Refers: ASTM D2651-90(1995) - Standard Guide for Preparation of Metal Surfaces for Adhesive Bonding
• Effective Date: 10-Oct-2001
• Refers: ASTM E691-99 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 10-May-1999
• Refers: ASTM D3933-98 - Standard Guide for Preparation of Aluminum Surfaces for Structural Adhesives Bonding (Phosphoric Acid Anodizing)
• Effective Date: 10-May-1998

Overview

ASTM D4541-22 is the internationally recognized standard test method for evaluating the pull-off strength (adhesion) of coatings using portable adhesion testers. Developed by ASTM International, this standard provides uniform procedures for preparing, testing, and reporting the adhesion strength of coatings, primarily from metal substrates but also applicable to other rigid surfaces such as plastics and wood. The method uses portable tools that apply a perpendicular tensile load, making it suitable for both field and laboratory applications. The pull-off strength determined by this method is a critical performance indicator, often referenced in industry specifications for quality assurance, durability assessment, and coating qualification.

Key Topics

• Test Principle: A loading fixture (dolly) is bonded to the coated surface using an appropriate adhesive. The portable adhesion tester then applies a tensile load perpendicular to the surface until either the fixture is detached (test to fracture) or a predefined load is achieved (pass/fail criterion).
• Protocols and Methods:
  • Two main test protocols:
    • Protocol 1 (Test to Fracture): Measures maximum force until failure.
    • Protocol 2 (Pass/Fail): Verifies if the coating can withstand a specified load.
  • Five types of portable adhesion testers (Test Methods B-F), each with specific apparatus and procedural details.
• Result Variability:
  • Test results can be affected by factors such as adhesive type, loading rate, fixture size, environmental conditions, surface preparation, and whether the coating is scored.
  • Consistency in testing parameters is essential for comparative or statistical analysis.
• Substrate and Surface Considerations:
  • Optimal for flat, rigid surfaces.
  • Results may vary on non-flat or flexible substrates.
  • Primarily designed for metal coatings but may be suitable for certain plastics and woods if modified accordingly.
• Destructive Nature:
  • The pull-off test can be destructive, often requiring localized repair after testing.

Applications

• Quality Assurance: Essential for verifying that protective and decorative coatings adhere adequately to metal substrates in industries such as construction, automotive, marine, and manufacturing.
• Coating Qualification: Used to test new formulations or application methods before field deployment.
• Maintenance and Field Assessment: Valuable for assessing the condition of existing coatings in situ, enabling maintenance planning and failure analysis.
• Regulatory Compliance: Frequently specified in procurement and manufacturing contracts to meet safety, performance, and durability requirements.
• Comparative Evaluation: Allows for the comparison of adhesion performance between different coatings or application processes, provided the same protocol and equipment are used.
• Research and Development: Supports R&D activities related to surface preparation, coating chemistry, and adhesive technology.

Related Standards

• ASTM D7234 - Standard Test Method for Pull-Off Adhesion Strength of Coatings on Concrete Using Portable Pull-Off Adhesion Testers.
• ASTM D2651 - Guide for Preparation of Metal Surfaces for Adhesive Bonding.
• ASTM D3933 - Guide for Preparation of Aluminum Surfaces for Structural Adhesives Bonding.
• ASTM E691 - Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method.

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Keywords: ASTM D4541, pull-off strength, coating adhesion, portable adhesion tester, metal substrate coating test, tensile adhesion, field adhesion test, paint adhesion test, coatings performance testing, ASTM coating standards.

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: D4541 − 22
Standard Test Method for
Pull-Off Strength of Coatings Using Portable Adhesion
Testers
This standard is issued under the fixed designation D4541; 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.
1. Scope* that coatings can be tested even though only one side is
accessible. Measurements are limited by the strength of adhe-
1.1 This test method covers a procedure for evaluating the
sive bonds between the loading fixture and the specimen
pull-off strength (commonly referred to as adhesion) of a
surface or the cohesive strengths of the glue, coating layers,
coating system from metal substrates. Pull-off strength of
and substrate.
coatings from concrete is described in Test Method D7234.
This test offers two test protocols. Protocol 1 (test to fracture) 1.4 This test can be destructive and spot repairs may be
determines the greatest perpendicular force (in tension) that a necessary.
surface area can bear before a plug of material is detached.
1.5 The values stated in either SI units or inch-pound units
Protocol 2 (pass/fail) determines if the coated surface remains
are to be regarded separately as standard. The values stated in
intact at a defined load criteria. Fracture will occur along the
each system are not necessarily exact equivalents; therefore, to
weakest plane within the system comprised of the test fixture,
ensure conformance with the standard, each system shall be
glue, coating system, and substrate, and will be exposed by the
used independently of the other, and values from the two
fracture surface. This test method maximizes tensile stress as
systems shall not be combined.
compared to the shear stress applied by other methods, such as
1.6 This standard does not purport to address all of the
scratch or knife adhesion, and results may not be comparable.
safety concerns, if any, associated with its use. It is the
NOTE 1—The procedure in this standard was developed for metal
responsibility of the user of this standard to establish appro-
substrates,butmaybeappropriateforotherrigidsubstratessuch as plastic
andwood.Factorssuchasloadingrateandflexibilityofthesubstratemust
priate safety, health, and environmental practices and deter-
be addressed by the user/specifier.
mine the applicability of regulatory limitations prior to use.
NOTE 2—The procedure in this standard was developed for use on flat
1.7 This international standard was developed in accor-
surfaces. The results could have greater variability with lower values and
dance with internationally recognized principles on standard-
averages for surfaces other than flat.
ization established in the Decision on Principles for the
1.2 Pull-off strength measurements depend upon material,
Development of International Standards, Guides and Recom-
instrumentation and test parameters. Results obtained by each
mendations issued by the World Trade Organization Technical
test method may give different results. Results should only be
Barriers to Trade (TBT) Committee.
assessed for each test method and not be compared with other
instruments. There are five instrument types, identified as Test
2. Referenced Documents
Methods B-F. It is imperative to identify the test method used
2.1 ASTM Standards:
when reporting results.
D2651 GuideforPreparationofMetalSurfacesforAdhesive
NOTE 3—Method A, which appeared in previous versions of this
Bonding
standard, has been eliminated as its main use is for testing on concrete
substrates (see Test Method D7234). D3933 Guide for Preparation of Aluminum Surfaces for
Structural Adhesives Bonding (Phosphoric Acid Anodiz-
1.3 Thistestmethoddescribesaclassofapparatusknownas
ing)
portable pull-off adhesion testers. They are capable of apply-
D7234 Test Method for Pull-OffAdhesion Strength of Coat-
ing a concentric load and counter load to a single surface so
ings on Concrete Using Portable Pull-Off Adhesion Tes-
ters
E691 Practice for Conducting an Interlaboratory Study to
This test method is under the jurisdiction of ASTM Committee D01 on Paint
Determine the Precision of a Test Method
and Related Coatings, Materials, andApplications and is the direct responsibility of
Subcommittee D01.46 on Industrial Protective Coatings.
Current edition approved July 1, 2022. Published July 2022. Originally approved
in 1993. Last previous edition approved in 2017 as D4541 – 17. DOI: 10.1520/ For referenced ASTM standards, visit the ASTM website, www.astm.org, or
D4541-22. contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
The term adhesion tester may be somewhat of a misnomer, but its adoption by Standards volume information, refer to the standard’s Document Summary page on
two manufacturers and at least two patents indicates continued usage. the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4541 − 22
3. Summary of Test Method 5. Apparatus
5.1 Adhesion Tester, commercially available, or comparable
3.1 The general pull-off test is performed by securing a
apparatus to the specific examples listed in AnnexA1 – Annex
loading fixture (dolly, stud) normal (perpendicular) to the
A5.
surface of the coating with a glue. After the glue is cured, a
5.1.1 Loading Fixtures,having a flat surface on one end that
testing apparatus is attached to the loading fixture and aligned
can be adhered to the coating and a means of attachment to the
to apply tension normal to the test surface.The force applied to
tester on the other end. Optimal size of the loading fixture is
the loading fixture is then gradually and uniformly increased
determined by the adhesion tester capabilities. The fixture and
and monitored until either the loading fixture is detached, or a
tester combination should be chosen so that the expected
specifiedloadvalueisreachedandthetestterminated.Thetwo
maximum pull load the coating will be subjected to during the
common uses of this test are test to fracture (Protocol 1), and
test is within the range of the tester.
pass/fail testing (Protocol 2). Test to fracture is used to
5.1.2 Detaching Assembly (adhesion tester), having a cen-
determine a maximum load that can be achieved when a plug
tral grip for engaging the fixture.
of material is detached with the selected testing parameters.
5.1.3 Base,onthedetachingassembly,oranannularbearing
Pass/fail is used to verify the results of a testing procedure can
ring if needed for uniformly pressing against the coating
meet a minimum load criterion. When the loading fixture is
surface around the fixture either directly, or by way of an
detached, the exposed surface represents the plane of limiting
intermediate bearing ring. A means of aligning the base is
strength within the system. The nature of the plane of fracture
needed so that the resultant force is normal to the surface.
is qualified in accordance with the percent of adhesive and
5.1.4 Meansofmovingthegripawayfromthebasetoallow
cohesive failures, and the actual interfaces and layers involved.
the loading of the fixture in as smooth and uniform a manner
The reported load is computed based on the maximum indi-
aspossibleandsothatatorsionfree,co-axial(opposingpullof
cated load, the instrument calibration data, and the original
the grip and push of the base along the same axis) force results
surface area stressed. Results obtained using different test
between them.
devices will vary because the results depend on instrumenta-
5.1.5 Timer, or means of limiting the loading rate.Atimer is
tion parameters. Variations in results are also expected when
the minimum equipment when used by the operator along with
tests are performed under different test procedures or environ-
the force indicator in 5.1.6.
mental conditions (see 4.2).
5.1.6 Force Indicator and Calibration Information, for
determining the actual force delivered to the loading fixture.
4. Significance and Use
5.2 Solvent, or other means for cleaning the loading fixture
4.1 The pull-off strength of a coating is a performance
surface. Finger prints, moisture, oxides, and dust tend to be the
property that may be referenced in specifications. This test
primary contaminants.
method serves as a means for uniformly preparing and testing
5.3 Sandpaper, or other means, used to roughen the surfaces
coated surfaces, and evaluating and reporting the results. This
for glue application and adherence to the coating. When using
test method is applicable to any portable apparatus meeting the
sandpaper it is recommended to use 100 grit or finer.
requirements for determining the pull-off strength of a coating
5.4 Glue—the material used for securing the loading fixture
in this standard (see Annex A1 – Annex A5).
to the coating. Two component epoxies and cyanoacrylates are
4.2 Variations in results with the same coating are likely
twocommonlyusedglues.Selectagluethatdoesnotaffectthe
when any parameter of the test is changed. This includes
coating properties, flow through the coating or attack the
change in glue, load fixture size, substrate coating cure time,
coating.
pull rate, environmental conditions, if the coating is scored, or
5.5 Clamps,magnetic,mechanical,tapeorsimilar,ifneeded
usingadifferentdevice.Therefore,whenaseriesofresultswill
for holding the fixture in place while the glue cures.
be compared with one another or used for statistical analysis,
5.6 Cotton Swabs, or other means for removing excess glue
the type of apparatus, substrate, test procedures, glue type, and
and defining the adhered area. Any method for removing
if scoring is used should be the same for the pulls considered.
excess glue that damages the surface, such as scoring (see 6.7),
Itisrecommendedthattheseparametersandtheenvironmental
must generally be avoided since induced surface flaws may
conditions allowed during the test be mutually agreed upon
cause premature failure of the coating.
between the interested parties.
5.7 Scoring Tool,circularholecutter,orsimilartooltoscore
4.3 The purchaser or specifier shall designate a specific test
the coating to the substrate around the loading fixture.
method procedure; B, C, D, E, or F and test Protocol; 1, or 2,
when calling out this standard. In cases where either the
6. Test Preparation
Protocol or a pass/fail criterion is not designated, Protocol 1
shall be used. 6.1 Themethodforselectingthecoatingsitestobeprepared
for testing depends upon the objectives of the test and
agreements between the contracting parties. There are,
however, a few physical restrictions imposed by the general
Reference to potential variability of the adhesion test has been made in various
method and apparatus.The following requirements apply to all
publications, including the assessment of variability completed for the test method
found in ASTM Research Report RR:D01-1147. sites:
D4541 − 22
6.1.1 The selected test area must be large enough to accom- prevent micro-cracking in the coating or glue, since such
modatethespecifiednumberofreplicatetests.Thesurfacemay cracks may cause reduced values. Scored samples constitute a
have any orientation with reference to gravitational pull. Each differenttestprocedure,andshouldbeclearlyreportedwiththe
loading fixture must be separated by at least the distance results. Scoring may be required for thick-film coatings,
needed to accommodate the detaching apparatus. For Protocol reinforced coatings and elastomeric coatings. Scoring, if
1 or to statistically characterize a test area, three or more performed, can be completed before or after the load fixture is
replications are required. glued to the coating.When performed, scoring shall be done in
6.1.2 The selected test areas must also have enough perpen- a manner that ensures the cut is made normal to the coating
surface, in a manner that does not twist or torque the test area
dicular and radial clearance to accommodate the apparatus, be
flatenoughtopermitalignment,andberigidenoughtosupport or impart the loading fixture, and minimizes heat generation,
edge damage, or microcracks to the coating or glue and the
the counter force. It should be noted that measurements close
to an edge may not be representative of the coating as a whole. substrate. For thick coatings it is recommended to cool the
coating and substrate during the cutting process with water
6.2 Since the rigidity of the substrate affects results of the
lubrication.
test and is not a controllable test variable in field
measurements, some knowledge of the substrate thickness and NOTE 5—A template made from wood with a hole of the same size as
the scoring tool drilled through it and secured to the surface may be an
composition should be reported for subsequent analysis or
effective method to limit sideways movement of the scoring tool.
laboratory comparisons. For example, steel substrate of less
NOTE 6—Scoring requirements will vary depending on coating system,
than 3.2 mm ( ⁄8 in.) thickness usually reduces test results
chemistry, and thickness. A direct comparison of the unscored result to a
compared to 6.4 mm ( ⁄4-in.) thick steel substrates.
scored result is one method to determine if scoring should be performed.
Other methods for making this determination may be employed with
6.3 Subject to the requirements of 6.1, select representative
agreement between the purchaser and seller. Scoring should not be
test areas and clean the surfaces in a manner that will not affect
considered for coatings less than 20 mils.
integrity of the coating or leave a residue.To reduce the risk of
6.8 Note the approximate temperature, relative humidity,
gluefractureaffectingthetest,thesurfaceofthecoatingcanbe
andotherpertinentenvironmentalconditionsduringthetimeof
lightly abraded to promote adhesion of the glue to the surface.
test.
If the surface is abraded, care must be taken to prevent
significant loss of coating thickness. Clean the area to remove
7. Test Procedure
particulates after abrading. Use of a solvent may be necessary
to remove all contaminants. If a solvent is required, select one
7.1 Test Methods:
that does not compromise the integrity of the coating.
7.1.1 Test Method A (discontinued).
6.4 Clean the loading fixture surface as indicated by the
7.1.2 Test Method B — Fixed Alignment Adhesion Tester
apparatus manufacturer. Failures at the fixture-glue interface Type II:
can often be avoided by treating the fixture surfaces in
7.1.2.1 Operate the instrument in accordance with
accordance with an appropriate ASTM standard practice for
Annex A1.
preparing metal surfaces for glue bonding.
7.1.3 Test Method C — Self-Alignment Adhesion Tester
Type III:
NOTE 4—Guides D2651 and D3933 are typical of well-proven methods
for improving adhesive bond strengths to metal surfaces.
7.1.3.1 Operate the instrument in accordance with
Annex A2.
6.5 Prepare the glue in accordance with the glue manufac-
7.1.4 Test Method D — Self-Alignment Adhesion Tester
turer’s recommendations. Apply the glue to the fixture or the
Type IV:
surface to be tested, or both, using a method and thickness
7.1.4.1 Operate the instrument in accordance with
recommendedbythegluemanufacturer.Becertaintoapplythe
Annex A3.
glue across the entire fixture surface. Position the fixture on the
surface to be tested. Carefully remove any excess glue from 7.1.5 Test Method E — Self-Alignment Adhesion Tester
aroundthefixture.(Warning—Movement,especiallytwisting,
Type V:
can cause tiny bubbles to coalesce into large holidays that
7.1.5.1 Operate the instrument in accordance with
constitute stress discontinuities during testing which may lead
Annex A4.
to glue fracture.)
7.1.6 Test Method F — Self-Alignment Adhesion Tester
Type VI:
6.6 Based on the glue manufacturer’s recommendations and
the anticipated environmental conditions, allow enough time 7.1.6.1 Operate the instrument in accordance with
Annex A5.
for the glue to cure. During the glue set and early cure stage,
aconstantcontactpressureshouldbemaintainedonthefixture.
7.2 Select an adhesion-tester with a detaching assembly and
Magnetic or mechanical clamping systems work well, but
loading fixture size that has a force calibration spanning the
systems relying on tack, such as masking tape, should be used
range of expected values. Mid-range measurements are
with care to ensure that they do not relax with time and allow
recommended, but read the manufacturer’s operating instruc-
air to intrude between the fixture and the test area.
tions before proceeding.The adhesion tester shall be calibrated
6.7 When scoring around the test surface is agreed upon at the lesser of the manufacturer’s recommended frequency or
between the purchaser and seller, extreme care is required to every three years.
D4541 − 22
7.3 If a bearing ring or comparable device (5.1.3)istobe
used, place it concentrically around the loading fixture on the
coating surface. If shims are required when a bearing ring is
employed, place them between the tester base and bearing ring
rather than on the coating surface.
7.4 Carefully connect the central grip of the detaching
assembly to the loading fixture without bumping, bending, or
otherwise prestressing the sample and connect the detaching
FIG. 1 Specimen Description
assembly to its control mechanism, if necessary. For nonhori-
zontal surfaces, it may be necessary with some devices to
support the detaching assembly so that its weight does not
d = equivalent diameter of the original surface area stressed
impacttheloadingfixtureandcontributetotheforceexertedin
the test. Follow the manufacturer’s recommendations. having units of millimeters (inches). This is usually
equal to the diameter of the loading fixture.
7.5 Align the device according to the manufacturer’s in-
8.3 For tests where the load fixture becomes detached from
structions and set the force indicator to zero.
the tested surface, visually estimate the percent of coating
NOTE 7—Proper alignment is critical. If alignment of the device is
adhesive and cohesive fracture and glue failure in accordance
required, use the procedure recommended by the manufacturer of the
to their respective areas and location within the test system
adhesion tester and report the procedure used.
comprised of coating and glue layers. Glue fracture or failure
7.6 Increase the load to the fixture in as smooth, consistent,
is defined as a visible separation of the glue from itself, the
and uniform a manner and rate as possible. The rate of pull
coating or load fixture.Aconvenient scheme that describes the
shall be 1 MPa/s (150 psi/s) or less. The rate should be set so
total test system is outlined in 8.3.1 through 8.3.3.
that the test is completed in less than 100 seconds. If multiple
8.3.1 Describe the specimen as substrate A, upon which
tests are required, the rate of pull shall be similar for each test.
successive coating layers B, C, D, etc., have been applied,
including the glue, Y, that secures the fixture, Z, to the top coat
NOTE8—Achangeinloadfixturesizemayresultinachangeintherate
(Fig. 1).
of pull depending on the equipment used.Achange in rate of pull or load
fixture size will result in variation of results.
8.3.2 Designate cohesive fractures by the layers within
which they occur as B, C, D, Y, etc., and the visually estimated
7.7 The test is completed when the fixture is detached from
percent of each.
the substrate, pass/fail test criteria is met or maximum pull
8.3.3 Designate adhesive fractures and glue failure by the
strength for the instrument is reached. For pass/fail tests, the
interfaces at which they occur as A/B, B/C, C/D, Y/Z, etc., and
test may be terminated at any point after the test criterion has
the visually estimated percent of each.
been reached.
8.4 A result that appears to be significantly different from
7.8 Record information required for the Report (see Section
other results (see repeatability limits in 10.1.1) may be caused
9).
by a mistake in test procedure performance, recording or
7.9 If a plug of material is detached, label and store the
calculating. If any of these are not the cause, then examine the
fixture for qualification of the failed surface in accordance with
experimental circumstances surrounding this run. If an irregu-
8.3.
lar result can be attributed to an experimental cause, drop this
result from the analysis. However, do not discard a result
7.10 Report any departures from the procedure such as
unless there are valid nonstatistical reasons for doing so or
possible misalignment, hesitations in the force application, etc.
unless the result is a statistical outlier. Valid nonstatistical
reasons for dropping results include alignment of the apparatus
8. Calculation or Interpretation of Results
that is not normal to the surface, poor definition of the area
8.1 If instructed by the instrument manufacturer, use the
stressedduetoimproperapplicationoftheglue,poorlydefined
instrument calibration factors to convert the indicated load for
glue lines and boundaries, holidays in the glue caused by voids
each test into the actual load applied.
or inclusions, improperly prepared surfaces, improperly scored
surfaces,varyingtherateofloadingduringthetest,varyingthe
8.2 Either use the calibration chart supplied by the manu-
rate of loading between tests, and sliding or twisting the fixture
facturer or compute the relative load applied to each coating
during the initial cure. Scratched or scored samples may
sample as follows:
contain stress concentrations leading to premature fractures.
X 5 4F/πd (1)
8.5 Document any test where the load limit of the testing
where:
equipment is reached.
X = greatest mean pull-off load applied during a pass/fail
8.6 Protocol 1 (Test to fracture) see Fig. 2 Flow Chart.
test, or the pull-off load achieved at fracture. Both have
8.6.1 Unless otherwise agreed to between the purchaser and
units of MPa (psi),
seller, disregard test results with visually estimated glue
F = actual load applied to the test surface as determined in
fracture greater than 1/4 of the loading area. Use caution when
8.1, and
using data from tests that include any visible glue fracture or
D4541 − 22
FIG. 2 Flow Chart
where the equipment capacity is exceeded for analysis as the the test procedure and make adjustments to reduce glue
results may not be statistically relevant. fracture or indicate the test is indeterminate.
NOTE 9—Any amount of glue fracture will result in a reduction of the
8.7 Protocol 2 (Pass/fail test), see Fig. 2 Flow Chart.
maximum test load measured by the testing apparatus
8.7.1 Thetestcanbeterminatedaftertheminimumcriterion
NOTE10—Whensubjectedtopull-offloads,anelastomericcoatingmay
has been met. elongate, and if the elongation or strain is sufficient, then the failure can
beinducedbyasimulatedpeeltypeloadstartingattheedgesofthescored
8.7.2 A test is passing when the maximum load applied is
sample. To reduce this effect proper scoring and test fixture alignment
greater than or equal to the pass/fail criteria.
techniques should be employed. As well, low loading rates should be
8.7.3 If the maximum load is less than the pass/fail criteria,
avoided to reduce the time the elastomeric coating is under stress. These
the test is either a failing test or an indeterminate test due to
factors do not preclude pull-off strength testing of elastomeric materials
glue fracture. A test result is indeterminate when there is a but should be noted when evaluating results.
visible amount of glue fracture (visibly detectable glue fracture
9. Report
is defined as glue failure of 5 % or more of the loading area)
that occurred during the test and the maximum load is less than 9.1 Report the following information:
the pass/fail criteria. An indeterminate test may be redone to 9.1.1 Date, test location, testing agent,
determine a passing or failing result. If the test is redone, and 9.1.2 Brief description of the general nature of the test, such
glue fracture persists at a load below the test criteria, review as, field or laboratory testing, generic type of coating, etc.
D4541 − 22
TABLE 1 Adhesion Testing Method B, Pull-Off Strength (psi)
9.1.3 Temperature and relative humidity and any other
pertinent environmental conditions during the test period. Repeatability Reproducibility
Repeatability Reproducibility
Coating Average Standard Standard
9.1.4 Description of the apparatus used, including: appara-
Limit Limit
Deviation Deviation
tus manufacturer and model number, last calibration date,
x¯sr sR r R
loading fixture type and dimensions, and bearing ring type and B 1195 278 330 777 925
C 549 109 117 305 326
dimensions.
D 1212 412 483 1155 1351
9.1.5 Description of the test system, if possible, by the
E 1385 192 276 537 774
Repeatability Reproducibility
indexingschemeoutlinedin8.3including:productidentityand
Coating Average
Limit Limit
generic type for each coa
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D4541 − 17 D4541 − 22
Standard Test Method for
Pull-Off Strength of Coatings Using Portable Adhesion
Testers
This standard is issued under the fixed designation D4541; 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.
1. Scope*
1.1 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. This test offers two test
protocols. Protocol 1 (test to fracture) determines the greatest perpendicular force (in tension) that a surface area can bear before
a plug of material is detached. Protocol 2 (pass/fail) determines if the coated surface remains intact at a defined load criteria.
Fracture will occur along the weakest plane within the system comprised of the test fixture, glue, 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 comparable.
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.
NOTE 2—The procedure in this standard was developed for use on flat surfaces. Depending on the radius of the surface, the The results could have greater
variability with lower values and averages.averages for surfaces other than flat.
1.2 Pull-off strength measurements depend upon material, instrumentation and test 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 results.
NOTE 3—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).
1.3 This test method describes a class of apparatus known as portable pull-off adhesion testers. 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 adhesive bonds between the loading fixture and the specimen surface or the cohesive
strengths of the glue, coating layers, and substrate.
1.4 This test can be destructive and spot repairs may be necessary.
1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
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
Subcommittee D01.46 on Industrial Protective Coatings.
Current edition approved Aug. 1, 2017July 1, 2022. Published September 2017July 2022. Originally approved in 1993. Last previous edition approved in 20092017 as
ɛ1
D4541 – 09D4541 – 17. . DOI: 10.1520/D4541-17.10.1520/D4541-22.
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 standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4541 − 22
system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used
independently of the other, and values from the two systems shall not be combined.
1.6 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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.7 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.
2. Referenced Documents
2.1 ASTM Standards:
D2651 Guide for Preparation of Metal Surfaces for Adhesive Bonding
D3933 Guide for Preparation of Aluminum Surfaces for Structural Adhesives Bonding (Phosphoric Acid Anodizing)
D7234 Test Method for Pull-Off Adhesion Strength of Coatings on Concrete Using Portable Pull-Off Adhesion Testers
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3. Summary of Test Method
3.1 The general pull-off test is performed by securing a loading fixture (dolly, stud) normal (perpendicular) to the surface of the
coating with a glue. After the glue is cured, a testing apparatus is attached to the loading fixture and aligned to apply tension normal
to the test surface. The force applied to the loading fixture is then gradually and uniformly increased and monitored until either
the loading fixture is detached, or a specified load value is reached and the test terminated. The two common uses of this test are
test to fracture (Protocol 1), and pass/fail testing (Protocol 2). Test to fracture is used to determine a maximum load that can be
achieved when a plug of material is detached with the selected testing parameters. Pass/fail is used to verify the results of a testing
procedure can meet a minimum load criterion. When the loading fixture is detached, the exposed surface represents the plane of
limiting strength within the system. The nature of the plane of fracture is qualified in accordance with the percent of adhesive and
cohesive failures, and the actual interfaces and layers involved. The reported load is computed based on the maximum indicated
load, the instrument calibration data, and the original surface area stressed. Results obtained using different test devices will vary
because the results depend on instrumentation parameters. Variations in results are also expected when tests are performed under
different test procedures or environmental conditions (see 4.2).
4. Significance and Use
4.1 The pull-off strength of a coating is a performance property that may be referenced in specifications. This test method serves
as a means for uniformly preparing and testing coated surfaces, and evaluating and reporting the results. This test method is
applicable to any portable apparatus meeting the requirements for determining the pull-off strength of a coating in this standard
(see Annex A1 – Annex A5Annexes).).
4.2 Variations in results with the same coating are likely when any parameter of the test is changed. This includes change in glue,
load fixture size, substrate coating cure time, pull rate, environmental conditions, if the coating is scored, or using a different
device. Therefore, when a series of results will be compared with one another or used for statistical analysis, the type of apparatus,
substrate, test procedures, glue type, and if scoring is used should be the same for the pulls considered. It is recommended that
these parameters and the environmental conditions allowed during the test be mutually agreed upon between the interested parties.
4.3 The purchaser or specifier shall designate a specific test method procedure; B, C, D, E, or F and test Protocol; 1, or 2, when
calling out this standard. In cases where either the Protocol or a pass/fail criterion is not designated, Protocol 1 shall be used.
5. Apparatus
5.1 Adhesion Tester, commercially available, or comparable apparatus to the specific examples listed in Annex A1 – Annex A5.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Reference to potential variability of the adhesion test has been made in various publications, including the assessment of variability completed for the test method found
in ASTM Research Report RR:D01-1147.
D4541 − 22
5.1.1 Loading Fixtures, having a flat surface on one end that can be adhered to the coating and a means of attachment to the tester
on the other end. Optimal size of the loading fixture is determined by the adhesion tester capabilities. The fixture and tester
combination should be chosen so that the expected maximum pull load the coating will be subjected to during the test is within
the range of the tester.
5.1.2 Detaching Assembly (adhesion tester), having a central grip for engaging the fixture.
5.1.3 Base, on the detaching assembly, or an annular bearing ring if needed for uniformly pressing against the coating surface
around the fixture either directly, or by way of an intermediate bearing ring. A means of aligning the base is needed so that the
resultant force is normal to the surface.
5.1.4 Means of moving the grip away from the base to allow the loading of the fixture in as smooth and uniform a manner as
possible and so that a torsion free, co-axial (opposing pull of the grip and push of the base along the same axis) force results
between them.
5.1.5 Timer, or means of limiting the loading rate. A timer is the minimum equipment when used by the operator along with the
force indicator in 5.1.6.
5.1.6 Force Indicator and Calibration Information, for determining the actual force delivered to the loading fixture.
5.2 Solvent, or other means for cleaning the loading fixture surface. Finger prints, moisture, oxides, and dust tend to be the primary
contaminants.
5.3 Sandpaper, or other means, used to roughen the surfaces for glue application and adherence to the coating. When using
sandpaper it is recommended to use 100 grit or finer.
5.4 Glue—the material used for securing the loading fixture to the coating. Two component epoxies and cyanoacrylates are two
commonly used glues. Select a glue that does not affect the coating properties, flow through the coating or attack the coating.
5.5 Clamps, magnetic, mechanical, tape or similar, if needed for holding the fixture in place while the glue cures.
5.6 Cotton Swabs, or other means for removing excess glue and defining the adhered area. Any method for removing excess glue
that damages the surface, such as scoring (see 6.7), must generally be avoided since induced surface flaws may cause premature
failure of the coating.
5.7 Scoring Tool, circular hole cutter, or similar tool to score through the coating to the substrate around the loading fixture.
6. Test Preparation
6.1 The method for selecting the coating sites to be prepared for testing depends upon the objectives of the test and agreements
between the contracting parties. There are, however, a few physical restrictions imposed by the general method and apparatus. The
following requirements apply to all sites:
6.1.1 The selected test area must be large enough to accommodate the specified number of replicate tests. The surface may have
any orientation with reference to gravitational pull. Each loading fixture must be separated by at least the distance needed to
accommodate the detaching apparatus. For Protocol 1 or to statistically characterize a test area, three or more replications are
required.
6.1.2 The selected test areas must also have enough perpendicular and radial clearance to accommodate the apparatus, be flat
enough to permit alignment, and be rigid enough to support the counter force. It should be noted that measurements close to an
edge may not be representative of the coating as a whole.
6.2 Since the rigidity of the substrate affects results of the test and is not a controllable test variable in field measurements, some
D4541 − 22
knowledge of the substrate thickness and composition should be reported for subsequent analysis or laboratory comparisons. For
1 1
example, steel substrate of less than 3.2 mm ( ⁄8 in.) thickness usually reduces test results compared to 6.4 mm ( ⁄4-in.) thick steel
substrates.
6.3 Subject to the requirements of 6.1, select representative test areas and clean the surfaces in a manner that will not affect
integrity of the coating or leave a residue. To reduce the risk of glue fracture affecting the test, the surface of the coating can be
lightly abraded to promote adhesion of the glue to the surface. If the surface is abraded, care must be taken to prevent significant
loss of coating thickness. Clean the area to remove particulates after abrading. Use of a solvent may be necessary to remove all
contaminants. If a solvent is required, select one that does not compromise the integrity of the coating.
6.4 Clean the loading fixture surface as indicated by the apparatus manufacturer. Failures at the fixture-glue interface can often
be avoided by treating the fixture surfaces in accordance with an appropriate ASTM standard practice for preparing metal surfaces
for glue bonding.
NOTE 4—Guides D2651 and D3933 are typical of well-proven methods for improving adhesive bond strengths to metal surfaces.
6.5 Prepare the glue in accordance with the glue manufacturer’s recommendations. Apply the glue to the fixture or the surface to
be tested, or both, using a method and thickness recommended by the glue manufacturer. Be certain to apply the glue across the
entire fixture surface. Position the fixture on the surface to be tested. Carefully remove any excess glue from around the fixture.
(Warning—WarningMovement,—Movement, especially twisting, can cause tiny bubbles to coalesce into large holidays that
constitute stress discontinuities during testing which may lead to glue fracture.)
6.6 Based on the glue manufacturer’s recommendations and the anticipated environmental conditions, allow enough time for the
glue to cure. During the glue set and early cure stage, a constant contact pressure should be maintained on the fixture. Magnetic
or mechanical clamping systems work well, but systems relying on tack, such as masking tape, should be used with care to ensure
that they do not relax with time and allow air to intrude between the fixture and the test area.
6.7 When scoring around the test surface is agreed upon between the purchaser and seller, extreme care is required to prevent
micro-cracking in the coating or glue, since such cracks may cause reduced values. Scored samples constitute a different test
procedure, and should be clearly reported with the results. Scoring may be required for thick-film coatings, reinforced coatings and
elastomeric coatings. Scoring, if performed, can be completed before or after the load fixture is glued to the coating. When
performed, scoring shall be done in a manner that ensures the cut is made normal to the coating surface, in a manner that does
not twist or torque the test area or impart the loading fixture, and minimizes heat generation, edge damage, or microcracks to the
coating or glue and the substrate. For thick coatings it is recommended to cool the coating and substrate during the cutting process
with water lubrication.
NOTE 5—A template made from wood with a hole of the same size as the scoring tool drilled through it and secured to the surface may be an effective
method to limit sideways movement of the scoring tool.
NOTE 6—-ScoringScoring requirements will vary depending on coating system, chemistry, and thickness. A direct comparison of the unscored result to
a scored result is one method to determine if scoring should be performed. Other methods for making this determination may be employed with agreement
between the purchaser and seller. Scoring should not be considered for coatings less than 20 mils.
6.8 Note the approximate temperature, relative humidity, and other pertinent environmental conditions during the time of test.
7. Test Procedure
7.1 Test Methods:
7.1.1 Test Method A (discontinued).
7.1.2 Test Method B — Fixed Alignment Adhesion Tester Type II:
7.1.2.1 Operate the instrument in accordance with
Annex A1.
D4541 − 22
7.1.3 Test Method C — Self-Alignment Adhesion Tester
Type III:
7.1.3.1 Operate the instrument in accordance with
Annex A2.
7.1.4 Test Method D — Self-Alignment Adhesion Tester
Type IV:
7.1.4.1 Operate the instrument in accordance with
Annex A3.
7.1.5 Test Method E — Self-Alignment Adhesion Tester
Type V:
7.1.5.1 Operate the instrument in accordance with
Annex A4.
7.1.6 Test Method F — Self-Alignment Adhesion Tester
Type VI:
7.1.6.1 Operate the instrument in accordance with
Annex A5.
7.2 Select an adhesion-tester with a detaching assembly and loading fixture size that has a force calibration spanning the range
of expected values. Mid-range measurements are recommended, but read the manufacturer’s operating instructions before
proceeding. The adhesion tester shall be calibrated at the lesser of the manufacturer’s recommended frequency or every three years.
7.3 If a bearing ring or comparable device (5.1.3) is to be used, place it concentrically around the loading fixture on the coating
surface. If shims are required when a bearing ring is employed, place them between the tester base and bearing ring rather than
on the coating surface.
7.4 Carefully connect the central grip of the detaching assembly to the loading fixture without bumping, bending, or otherwise
prestressing the sample and connect the detaching assembly to its control mechanism, if necessary. For nonhorizontal surfaces, it
may be necessary with some devices to support the detaching assembly so that its weight does not impact the loading fixture and
contribute to the force exerted in the test. Follow the manufacturer’s recommendations.
7.5 Align the device according to the manufacturer’s instructions and set the force indicator to zero.
NOTE 7—Proper alignment is critical. If alignment of the device is required, use the procedure recommended by the manufacturer of the adhesion tester
and report the procedure used.
7.6 Increase the load to the fixture in as smooth, consistent, and uniform a manner and rate as possible. The rate of pull shall be
1 MPa/s (150 psi/s) or less. The rate should be set so that the test is completed in less than 100 seconds. If multiple tests are
required, the rate of pull shall be similar for each test.
NOTE 8—A change in load fixture size may result in a change in the rate of pull depending on the equipment used. A change in rate of pull or load fixture
size will result in variation of results.
7.7 The test is completed when the fixture is detached from the substrate, pass/fail test criteria is met or maximum pull strength
for the instrument is reached. For pass/fail tests, the test may be terminated at any point after the test criterion has been reached.
7.8 Record information required for the Report (see Section 9).
D4541 − 22
FIG. 1 Specimen Description
7.9 If a plug of material is detached, label and store the fixture for qualification of the failed surface in accordance with 8.3.
7.10 Report any departures from the procedure such as possible misalignment, hesitations in the force application, etc.
8. Calculation or Interpretation of Results
8.1 If instructed by the instrument manufacturer, use the instrument calibration factors to convert the indicated load for each test
into the actual load applied.
8.2 Either use the calibration chart supplied by the manufacturer or compute the relative load applied to each coating sample as
follows:
X 5 4F/πd (1)
where:
X = greatest mean pull-off load applied during a pass/fail test, or the pull-off load achieved at fracture. Both have units of MPa
(psi),
F = actual load applied to the test surface as determined in 8.1, and
d = equivalent diameter of the original surface area stressed having units of millimeters (inches). This is usually equal to the
diameter of the loading fixture.
8.3 For tests where the load fixture becomes detached from the tested surface, visually estimate the percent of coating adhesive
and cohesive fracture and glue failure in accordance to their respective areas and location within the test system comprised of
coating and glue layers. Glue fracture or failure is defined as a visible separation of the glue from itself, the coating or load fixture.
A convenient scheme that describes the total test system is outlined in 8.3.1 through 8.3.3.
8.3.1 Describe the specimen as substrate A, upon which successive coating layers B,C,D, etc., have been applied, including the
glue, Y, that secures the fixture, Z, to the top coat (Fig. 1).
8.3.2 Designate cohesive fractures by the layers within which they occur as B,C,D,Y, etc., and the visually estimated percent of
each.
8.3.3 Designate adhesive fractures and glue failure by the interfaces at which they occur as A/B,B/C,C/D,Y/Z, etc., and the visually
estimated percent of each.
8.4 A result that appears to be significantly different from other results (see repeatability limits in 10.1.1) may be caused by a
mistake in test procedure performance, recording or calculating. If any of these are not the cause, then examine the experimental
circumstances surrounding this run. If an irregular result can be attributed to an experimental cause, drop this result from the
analysis. However, do not discard a result unless there are valid nonstatistical reasons for doing so or unless the result is a statistical
outlier. Valid nonstatistical reasons for dropping results include alignment of the apparatus that is not normal to the surface, poor
definition of the area stressed due to improper application of the glue, poorly defined glue lines and boundaries, holidays in the
glue caused by voids or inclusions, improperly prepared surfaces, improperly scored surfaces, varying the rate of loading during
the test, varying the rate of loading between tests, and sliding or twisting the fixture during the initial cure. Scratched or scored
samples may contain stress concentrations leading to premature fractures.
8.5 Document any test where the load limit of the testing equipment is reached.
D4541 − 22
FIG. 2 Flow Chart
8.6 Protocol 1 (Test to fracture) see Fig. 2 Flow Chart.
8.6.1 Unless otherwise agreed to between the purchaser and seller, disregard test results with visually estimated glue fracture
greater than 1/4 of the loading area. Use caution when using data from tests that include any visible glue fracture or where the
equipment capacity is exceeded for analysis as the results may not be statistically relevant.
8.7 Protocol 2 (Pass/fail test), see Fig. 2 Flow Chart.
8.7.1 The test can be terminated after the minimum criterion has been met.
8.7.2 A test is passing when the maximum load applied is greater than or equal to the pass/fail criteria.
8.7.3 If the maximum load is less than the pass/fail criteria, the test is either a failing test or an indeterminate test due to glue
fracture. A test result is indeterminate when there is a visible amount of glue fracture (visibly detectable glue fracture is defined
as glue failure of 5 % or more of the loading area) that occurred during the test and the maximum load is less than the pass/fail
D4541 − 22
criteria. An indeterminate test may be redone to determine a passing or failing result. If the test is redone, and glue fracture persists
at a load below the test criteria, review the test procedure and make adjustments to reduce glue fracture or indicate the test is
indeterminate.
NOTE 9—Any amount of glue fracture will result in a reduction of the maximum test load measured by the testing apparatus
NOTE 10—When subjected to pull-off loads, an elastomeric coating may elongate, and if the elongation or strain is sufficient, then the failure can be
induced by a simulated peel type load starting at the edges of the scored sample. To reduce this effect proper scoring and test fixture alignment techniques
should be employed. As well, low loading rates should be avoided to reduce the time the elastomeric coating is under stress. These factors do not preclude
pull-off strength testing of elastomeric materials but should be noted when evaluating results.
9. Report
9.1 Report the following information:
9.1.1 Date, test location, testing agent,
9.1.2 Brief description of the general nature of the test, such as, field or laboratory testing, generic type of coating, etc.
9.1.3 Temperature and relative humidity and any other pertinent environmental conditions during the test period.
9.1.4 Description of the apparatus used, including: apparatus manufacturer and model number, last calibration date, loading fixture
type and dimensions, and bearing ring type and dimensions.
9.1.5 Description of the test system, if possible, by the indexing scheme outlined in 8.3 including: product identity and generic
type for each coat and any other information supplied, and the substrate identity (thickness, type, orientation, etc.).
9.1.6 Glue used and cure time before test.
9.1.7 Method used to secure the loading fixture during glue cure, if any.
9.1.8 R
...