Paint & Pigments
Digital Pull-off Adhesion Tester
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:
This test method specifies a procedure for assessing the resistance of paints and coatings to separation from substrates when a right angle lattice pattern iscut into the coating, penetrating through to the substrate.
The method may be used for a quick pass/fail test. When applied to a multi-coat system, assessment of the resistance to separation of individual layers of thecoating from each other may be made.
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.
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.
BGD 500 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.