What goes in an ASTM D4541 pull-off adhesion test report?

This guide covers field pull-off tests of coatings on metal with portable testers under ASTM D4541-22. Coatings on concrete follow ASTM D7234-22 instead. It covers what the report records, not what a value means for the coating or which value passes.

What do you need before an ASTM D4541 pull-off test in the field?

Before an ASTM D4541 pull-off test in the field you need the specification's method letter, protocol and any pass load, plus the equipment and blank report fields that capture every parameter the standard says changes the result.

• The specification clause: method letter B to F, Protocol 1 or 2, the pass load for Protocol 2, and the number and location of tests.

• The tester named in the specification, with its serial number and calibration certificate.

• Dollies of the specified diameter, the specified glue, and the glue maker's cure time at the site temperature.

• An abrasive pad and degreaser; when the degreaser is alcohol or acetone, follow its safety data sheet (SDS), keep it away from ignition sources and follow site permit rules.

• A cutting tool, if the specification calls for scoring around the dolly.

• A dry film thickness gauge used to ASTM D7091-22 (ASTM, 2022); take a thickness reading at each dolly location.

• A camera and the report form.

Agree the repair before testing: ASTM D4541-22 states that "This test can be destructive and spot repairs may be necessary" (ASTM, 2022). The report should name who repairs each test spot and with which coating.

Which ASTM D4541 test method and protocol should the field report name?

The field report should name the ASTM D4541 edition, the method letter from B to F and the protocol, 1 or 2, in its header, because the standard treats each method as giving its own results. ASTM D4541-22 states that "It is imperative to identify the test method used when reporting results" (ASTM, 2022).

Write the edition in full as ASTM D4541-22, not ASTM D4541. The ASTM store lists earlier editions back to D4541-95e1, including D4541-17 and D4541-09e1, and Method A, which appeared in previous versions, "has been eliminated" in favor of ASTM D7234 for concrete (ASTM, 2022). A report citing Method A follows an older edition.

Record the method letter as designated and add the tester make and model next to it, so the reader can match the two. The protocol decides what the value means: Protocol 1 "determines the greatest perpendicular force (in tension) that a surface area can bear before a plug of material is detached", while Protocol 2 "determines if the coated surface remains intact at a defined load criteria" (ASTM, 2022). For Protocol 2, record the load applied and whether the coating stayed intact, not a fracture value it never reached.

How do you record the fracture location in a pull-off adhesion test report?

Record the fracture location in a pull-off adhesion test report for every dolly, as the share of the dolly face that broke within each layer and between each pair of layers. DeFelsko notes that ASTM D4541 and ISO 4624 "require the nature of the fracture to be recorded", and that fractures "are visually estimated and recorded as a percent of each" (DeFelsko, 2026).

Use three fracture types on every dolly:

1. Cohesive fracture: the break runs within one layer, with the same coating on the dolly face and on the surface.

2. Adhesive fracture: the break runs at an interface, with a different layer on the dolly face than on the surface.

3. Glue failure: the glue separates from itself, the coating or the dolly, with no coating visible on the dolly face.

Name the layers in order: substrate, primer, intermediate coat, topcoat, glue. A complete entry reads, for example, "70% cohesive in primer, 30% adhesive primer to intermediate" (illustrative). Add a photo of each dolly face next to its photo of the test spot.

The fracture type changes what the number means. ASTM D4541-22 states that measurements are limited by the strength of the bonds between fixture and surface or by "the cohesive strengths of the glue, coating layers, and substrate" (ASTM, 2022). A glue failure therefore shows only that the coating held at least that load.

Should a pull-off adhesion test report give each value or only the average?

A pull-off adhesion test report should give each value with its own fracture entry, and the mean and range for each test area after them. An average alone hides glue failures and mixed fracture types, which change what a single value means.

Each value matters for three reasons. First, the acceptance rule may apply to individual readings: ISO 16276-1:2025 sets out "inspection areas, sampling plans and acceptance/rejection criteria" for pull-off tests on steel structures (ISO, 2025), and a reader cannot apply such criteria to an average. Second, a mean that combines a glue failure at a low load with cohesive breaks at higher loads understates the coating. Third, ASTM D4541-22 recommends that results compared with one another or used for statistical analysis come from the same apparatus, substrate, procedure, glue type and scoring practice (ASTM, 2022), which a reader can only confirm value by value.

Give each value in the unit the specification uses, in MPa or psi, and do not mix the two. Then state the mean and range per area, the number of values in it, and which values, if any, were left out of the mean and why.

Why must a pull-off adhesion test report name the tester and dolly size?

A pull-off adhesion test report must name the tester and dolly size because pull-off values from different devices and fixture sizes are not comparable, so a value without them cannot be checked against another test. ASTM D4541-22 states that results "should only be assessed for each test method and not be compared with other instruments" (ASTM, 2022), and ISO 16276-1:2025 states that "The results obtained using such different types of equipment are not comparable" (ISO, 2025).

Record four items for the equipment:

• Tester make, model and serial number.

• Calibration date. One tester maker suggests that "a one-year calibration interval from the date the instrument was first put into service is a typical starting point" (DeFelsko, 2025).

• Dolly diameter, in millimeters. The same portable tester accepts 10, 14, 20 and 50 mm dollies, each with its own priming pressure (DeFelsko, 2025).

• Pull rate, if the tester or the specification sets one.

ASTM D4541-22 lists "load fixture size" and "using a different device" among the changes that make results vary with the same coating (ASTM, 2022). A later test on the same structure with a different tester or dolly is a new data set, not a repeat.

What site conditions belong in an ASTM D4541 field report?

The site conditions in an ASTM D4541 field report are the ones that change the pull-off result or the glue cure: air temperature and relative humidity, surface temperature, coating age, glue type and cure time, surface shape and whether the coating was scored. ASTM D4541-22 recommends that test parameters and "the environmental conditions allowed during the test be mutually agreed upon between the interested parties" (ASTM, 2022).

Record at each test location:

• Location: structure, area and a grid or elevation reference.

• Air temperature, relative humidity and surface temperature at gluing and at pulling.

• Coating age: application date and the coating's cure time before the test, since ASTM D4541-22 lists "substrate coating cure time" as a parameter (ASTM, 2022).

• Glue name, mix, cure time and cure temperature. One tester maker notes that cyanoacrylates "may be sufficient for smooth coatings, but two-part epoxies are preferred for porous or rough coatings" (DeFelsko, 2025).

• Surface shape: ASTM D4541-22 was developed for flat surfaces, and results "could have greater variability with lower values and averages for surfaces other than flat" (ASTM, 2022).

• Scoring: yes or no, and to what depth.

• Dry film thickness at each dolly.

How do you check an ASTM D4541 field report is complete?

Check an ASTM D4541 field report is complete by reading it against the table below before you leave the site, while a missing item can still be retested. Each row names the item, what complete looks like and what to do when it is missing.

The row that most often forces a retest is the fracture entry: without the percent by layer for each dolly, nobody can tell a coating value from a glue value. Sign and date the report on site, and keep the photos with it under the same test numbers. In Lubinpla, an organization's single work-log template can set these same report items for every work log its agent writes, though logs people write on the compose screen do not follow that template. If several engineers write these reports, a fixed template helps; see how to make every customer visit report follow one template.

What ASTM D4541 field report mistakes make results unusable?

The ASTM D4541 field report mistakes that make results unusable are the ones that remove the parameters ASTM D4541-22 says change the result, or that mix results the standard says not to compare. Six recur:

1. No method letter or edition, only "pull-off test to ASTM D4541".

2. Only an average, with no single values or fracture entries.

3. Glue failures reported as coating strength.

4. Values from a different tester or dolly size compared as if they were a repeat.

5. A product or project minimum written as if it were an ASTM limit; ASTM D4541-22 leaves the pass load to the specifier for Protocol 2 (ASTM, 2022).

6. No record of the repaired test spots.

Mistakes 3 and 4 do the most harm, because they produce a number that looks valid. Mistake 6 surfaces later: an unrecorded repair spot can look like a coating defect at the next inspection.