In order to perform satisfactorily, coatings must adhere to the substrates on which they are applied. In practice, three different test procedures are used to assess the resistance of paints and coatings to separation from substrates:
Adhesion of asingle coating or a multi-coat system of paint, varnish or related products is assessed by measuring the minimum tensile stress necessary to detach or rupture the coating in a direction perpendicular to the substrate. This method maximizes tensile stress as compared to the shear stress applied by other methods such as scratch adhesion and results may not be comparable. The test is performed by securing a loading fixture (dolly) perpendicular to the surface of the coating with an adhesive. After the adhesive is cured, a testing apparatus is attached to the loading fixture and aligned to apply tension perpendicular to the testsurface. The force applied is gradually increased and monitored until either a plug of coating material is detached, or a specified value is reached.
digital pull-off adhesion tester is a portable, hand-operated instrument which is used to measure the force required to pull a specified test diameter of coating away from its substrate using hydraulic pressure. The pressure is displayed on a digital LCD and represents the coating’s strength of adhesion to the substrate.
It evaluates the adhesion (pull-offstrength) of a coating by determining the greatest tensile pull-off force that it can bear before detaching. Breaking points, demonstrated by fractured surfaces,occur along the weakest plane within the system consisting of dolly, adhesive,coating layers and substrate.
① ISO 4624 《Paints and varnishes-Pull-offtest for adhesion》
② ASTM D 4541 《StandardTest Method for Pull-Off Strength of Coatings Using Portable Adhesion Testers》
③ ASTM D7234 《Standard Test Method for Pull-OffAdhesion Strength of Coatings on Concrete Using Portable Pull-Off Adhesion Testers》
Main Technical Parameters
■ Dolly Size： 20mm（Standard）；10mm、14mm、50mm（Optional）
■ Resolution： 0.01MPa（1psi）
■ Accuracy： ±1% Full scale
■ Max. Pull-off Pressure：Φ10mm dolly →0-80 MPa；Φ14mm dolly→0-40 MPa；
Φ20mm dolly→0-20 MPa；Φ50mm dolly→0-3.5 MPa；
■ Power：Built-in rechargeable lithium battery, and standard configuration charging adapter.
■ Adhesion Tester Size：360mm×75mm×115mm（L x W x H）
■ Adhesion Tester Weight：3KG
■ Packing List：
① Adhesion Tester with digital display
② 20mm Aluminum test dollies（20 pcs）
③ Cutting toll for 20mm dollies，
④ 3M Adhesive and glue gun
⑤ Micro-USB cable
⑥ Operation Manual
⑦ Carrying case
Coating or a multi-coat system of paint is applied/distributed to substrate uniformly witha certain thickness.
After coating has been dried or cured, adhere dolly to surface of coating directly with special adhesive.
After the adhesive is cured, use digital pull-off adhesion tester to attach the loading fixture and aligned to apply tension perpendicular to the test surface. Tester pull off the dolly at a speed of 1MPa/s by hydraulic pump, and measures the force required to pull a specified test diameter of coating away from its substrate using hydraulic pressure, this force is shown through the LCD oftester.
This test method covers the determination of the adhesion of organic coatings such aspaint, varnish, and lacquer when applied to smooth, flat(planar)panel surface.It has been found useful in providing relative ratings for a series of coated panels exhibiting significant difference in adhesion.
The materials under test are applied at uniform thickness to flat panels, usually sheet metal of uniform surface texture. After drying, the adhesion is determined by pushing the panels beneath a rounded stylus or loop that is loaded with increasing amount of weight until the coating is removed from the substrate surface.
◆ Portable design, can be used anywhere.
◆ Built-in rechargeable lithium battery, no need any external power source.
◆ Selectable directly four different sizes dolly for different resolution and testing range
◆ Get the testing results from LCD directly.
◆ Includes all tools needed for testing