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At BlastOne, we understand the critical role coating adhesion plays in achieving optimal results for your projects. Whether you’re working with metal, concrete, wood, or other substrates, a strong bond between the coating and the surface is essential for long-lasting performance and protection. Our comprehensive selection of coating adhesion testing tools empowers you to ensure the integrity of your coating systems and achieve superior quality finishes.
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DEFELSKO® POSITEST AT-A HYDRAULIC ADHESION TESTER KIT |
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DEFELSKO® POSITEST AT-M HYDRAULIC ADHESION TESTER KIT |
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STANDARD DOLLY ADHESION TEST KIT |
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DEFELSKO CH CROSS HATCH ADHESION TESTER |
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| DEFELSKO® POSITEST AT-A HYDRAULIC ADHESION TESTER KIT | DEFELSKO® POSITEST AT-M HYDRAULIC ADHESION TESTER KIT | STANDARD DOLLEY ADHESION | DEFELSKO CH CROSS HATCH ADHESION TESTER | |
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20mm Kit |
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50mm Kit |
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50x50mm Tile Kit |
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50 mm C1583 Kit |
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| 20mm Kit | 50mm Kit | 50x50mm Tile Kit | 50 mm C1583 Kit | |
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Adhesion testing belongs to the family of coating inspection tests known as destructive testing. These involve damaging a cured coating to provide a definitive answer to a query on a coating’s performance. In this instance the required test result is how well a cured coating has bonded to a substrate. An adhesion tester works by applying pulling force to a dolly bonded to a cured coating surface. The pressure at the point of failure is desired test result. Coating inspection standards will stipulate a pulling force that a coating will have to withstand to achieve approval.
While it might sound counterintuitive, the goal of adhesion testing is produce a coating failure. Adhesion testing identifies the strength of the bond between a coating and the underlying surface. This non-destructive method provides valuable insights into two key aspects:
By quantifying these factors, adhesion testing becomes a crucial tool for guaranteeing that your coating system meets the specific demands of the project and will deliver long-lasting performance.
The main consideration when choosing an adhesion testing system is the application. If you are consistently doing pull-off tests, you should invest in an automated unit that will give you the highest level of accuracy.
The manual pump system is great for regular testing, as the hydraulic pump will give you a consistent pull which is important when doing adhesion tests. The Manual Elcometer style pull off tester uses screws, and does not record the reading… We do not recommend this unit unless you are only doing occasional testing.
Dolly and coating preparation — clean and abrade the dolly and the coating
Glue and dolly application — prepare the glue, apply it to the dolly, and place the dolly on the coated surface. Allow the glue to cure properly.
Test area isolation — isolate the test area of the coating from the area surrounding the dolly by cutting or drilling (optional).
Pull-off test — perform the test
Analysis of the test results — examine and evaluate the dolly and coating to determine the nature of the coating fracture
Watch the full pull-off adhesion test procedure: How to Measure Adhesion Using the PosiTest AT Adhesion Tester.
The PosiTest AT Verifier is ideal for checking the accuracy and operation of adhesion testers and is an important component in fulfilling both ISO and in-house quality control requirements. The PosiTest AT Verifier and included documents allow the user to certify the accuracy of PosiTest Adhesion Testers.
Following a pull-off adhesion test, examining the dolly and the coated surface goes beyond just recording the pull-off force. In accordance with standards like ASTM D4541 and ISO 4624, many national and international regulations require documenting the nature of the fracture as well.
Fracture occurs within a coating layer (same coating on dolly face and coated surface)
Fracture occurs at the interface between layers (coating on dolly face differs from surface)
Visible separation of the glue from itself, the coating, or dolly (no coating visible on the dolly face)
Strong Bonds, Long-Lasting Performance: Ensuring Coating Adhesion
A coating’s success hinges on its ability to form a strong bond with the underlying surface, known as substrate adhesion. To guarantee optimal performance and longevity, various established methods assess the effectiveness of this bond. These techniques often involve specialized mechanical adhesion testers or a knife.
The Tensile Pull-Off Adhesion Test offers a precise measurement of a coating’s bond strength. In this method, a dolly (loading fixture) is glued to the coating, and a portable tester like the PosiTest AT progressively increases pulling force until the dolly detaches.
The force required, measured in MPa or psi, reveals the coating’s tensile pull-off strength, a key indicator of how well it adheres to the underlying surface.
Similar to the Pull-Off Test, the Push-Off Adhesion Test measures the force needed to detach a dolly from the surface using a pin and manual or hydraulic pressure. This test pushes the dolly upwards instead of pulling it down. Each dolly contains a center hole through which a pin is pushed using manual or hydraulic pressure.
The force required for detachment, measured in MPa or psi, indicates the coating’s bond strength.
The Knife Adhesion test establishes whether the adhesion level of a coating to a substrate or a coating to another coating (in a multi-coat system) is adequate.
Using a utility knife or metal straight edge, an X is cut into the coating system. The knife is then used to attempt to lift the coating from the substrate or from another coating layer below.
Review ASTM D6677 to learn more.
ASTM D3359 outlines two tape test methods for evaluating coating adhesion. Originally designed for steel substrates, these methods have been adapted for use on other hard surfaces and even softer materials like wood and plaster.
A special tape for testing adhesion is then firmly applied over the cross-hatch test area and removed quickly by pulling the tape back off of the test area to reveal the amount of coating lifted off by the test tape. The cross-hatched test area is then visually compared to the ASTM D3359 standard.
The scrape test uses a weighted beam with a rounded stylus. Panels are drawn under the stylus. The beam is loaded with increasing weight until the cured film scrapes off. Adhesion is measured in kilograms of force required for removal, indicating the film’s bond strength to the substrate. This test is adaptable for various coatings and substrates.
Depending on coating and substrate, refer to ASTM D2197, D2248, D2454, and D5178 standard test methods.
Learn how to maximize your protective coating and extend the lifetime of your assets
Refer to ASTM C1583 for a complete description of the test standard.
Refer to ASTM D3359 for a complete description of the test standard.
Refer to ASTM D7234 for a complete description of the test standard.
Refer to ASTM D4541 for a complete description of the test standard.
Refer to ASTM D6677 for a complete description of the test standard.
Refer to ASTM D2197 for a complete description of the test standard.
Refer to ISO 4624 for a complete description of the test standard.
Refer to BS ES 12004 for a complete description of the test standard.
Refer to BS EN 1542 for a complete description of the test standard.
ASTM D2370 describes one such test of elongation, tensile strength, and stiffness of organic films when tested as free films.
Organic coating adhesion to plastic substrates by mounting an aluminum stud and removing it with a tensile tester is covered in ASTM D5179.
ASTM D4145 describes a bending test for determining flexibility and adhesion of coatings on prepainted metallic substrates. These organic coatings are subjected to stresses when fabricated into products by roll forming, brake bending, or other deformation processes.
ASTM D4149 describes the formability and adhesion testing of factory applied zinc-rich primer/chromate complex coatings on steel. In this test, a coated specimen is biaxially stretched a given distance in an appropriate machine, adhesive tape is applied to the deformed area (dome) and then pulled off, and the amount of coating removed is compared with a photographic standard to determine the coating adhesion rating.
Adhesion is also a measurable result of some hardness tests made by pencil hardness, gravelometer, impact (falling dart, etc.), or mandrel bend. Coating chip-off should be recorded during these tests.
The Most Common Dolly for pull off adhesion testing is 20mm. Other sizes available include; 10, 14, 29 and 50mm general purpose dollies. The smaller the dolly, the high the pull-off force (same amount of applied pressure over a smaller area increases pressure on the coating and substrate). A 50mm dolly designed for achieving optimum results on concrete. A 50mm x 50mm square tile dolly for testing tile adhesive strength.
When utilized with a 50mm diameter dolly, naan adhesion tester is in a priming state until reaching a priming pressure of 16 psi. It is only after the priming pressure is reached that the instrument begins calculating and displaying the pull rate.
Adhesion testing is designed for use with rigid, structural substrates. A flexible substrate can adversely impact test accuracy and repeatability. Using an adhesion tester for measuring the adhesion of coatings applied to a brittle substrate typically results in the destruction of the substrate material, making it challenging to quantify the coating-substrate bond strength.
The PosiTest AT arrives fully calibrated and ready to measure. A Long-Form Certificate of Calibration traceable to NIST or PTB is included, which documents actual readings taken by your instrument at our calibration laboratory on standards traceable to a national metrology institute. Beware of ‘Certificates’ or ‘Certificates of Conformance’ offered by competitors. These typically do not include actual instrument readings, and are often insufficient to meet common quality requirements.
For added utility and convenience, PosiTest AT-A Automatic models also include a handy shoulder strap and rubberized grips.
The PosiTest AT 50 x 50 mm and PosiTest AT 50 mm C1583 (ATM50T and ATM50C) kits are supplied with self-aligning steel dollies that are precision-manufactured to comply with relevant standards.
DeFelsko steel and aluminum dollies are a single-use/consumable items and ideal for keeping a permanent visual record of testing.
DeFelsko does not provide or support the use of curved dollies for adhesion testing. In addition to affecting the surface area used in calculating pull-off strengths and the direction of the force lines (creating unwanted shear forces), most adhesion testing standards specifically call for the use of flat dollies.
While it is possible to obtain readings below this priming pressure with the AT-M model, the AT-A automatic does not allow the operator to build priming pressure very slowly and is therefore not suitable for use below the priming pressure.
Note that all reported adhesion values (including those obtained below the priming pressure) are subject to the PosiTest AT gage’s full-scale accuracy of ± 1% (± 30 psi, AT-M; ± 35 psi, AT-A).
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