ASTM D4541 - 22

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Designation: D4541 −22
Standard Test Method for
Pull-Off Strength of Coatings Using Portable Adhesion
Testers
1
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. 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 apply-
ing 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 adhe-
sive 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 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 appro-
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1.7 This international standard was developed in accor-
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
3
D2651 Guide for Preparation of Metal Surfaces for Adhesive
Bonding
D3933 Guide for Preparation of Aluminum Surfaces for
Structural Adhesives Bonding (Phosphoric Acid Anodiz-
ing)
D7234 Test Method for Pull-Off Adhesion Strength of Coat-
ings on Concrete Using Portable Pull-Off Adhesion Tes-
ters
E691 Practice for Conducting an Interlaboratory Study to
Determine the Precision of a Test Method
1
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 July 1, 2022. Published July 2022. Originally approved
in 1993. Last previous edition approved in 2017 as D4541 – 17. DOI: 10.1520/
D4541-22.
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.
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
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
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.
1

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 indi-

cated load, the instrument calibration data, and the original

surface area stressed. Results obtained using different test

devices will vary because the results depend on instrumenta-

tion parameters. Variations in results are also expected when

tests are performed under different test procedures or environ-

mental 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 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.

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.

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 cen-

tral 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

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:

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

6.1.1 The selected test area must be large enough to accom-

modate 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 perpen-

dicular 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 knowledge of the substrate thickness and

composition should be reported for subsequent analysis or

laboratory comparisons. For example, steel substrate of less

than 3.2 mm (

⁄

in.) thickness usually reduces test results

compared to 6.4 mm (

⁄

-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 manufac-

turer’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—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—Scoring 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.

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 instruc-

tions before proceeding. The adhesion tester shall be calibrated

at the lesser of the manufacturer’s recommended frequency or

every three years.

D4541 − 22

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摘要：

ASTM D4541 - 22 是美国材料与试验协会发布的涂层附着力测试标准，专门用于通过拉拔法测定涂层与基材之间的附着力强度。该标准涵盖了便携式附着力测试仪器的使用规范，适用于金属、混凝土、木材等多种基材上的涂层系统。通过执行该标准，用户可以获得涂层在垂直于基材方向上的抗拉脱能力数据，从而评估涂层的耐久性和施工质量。ASTM D4541 - 22 取代了旧版本，更新了仪器校准要求、测试步骤及结果处理细节，确保测试的一致性和准确性。该标准广泛应用于航空航天、船舶、建筑和工业涂装领域，是质量控制和

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