The Erichsen Model 525 measures coating adhesion using the peel strength according to standard ASTM D 4521.
The results of this test are generally not comparable to other adhesion test methods. Model 525 acts perpendicular to the coating and provides a tensile stress, where methods such as cross cut method use a shear stress.
Operation is simple. A test cylinder is stuck to the coating with an adhesive and the coating is pulled off under defined conditions. The tensile strength required for this and a visual inspection of the surface will provide the information required to determine the quality of the coating.
The Model 525 is made up of a circular housing with three legs containing a concentrically positioned compression spring. The housing is closed by means of a cylinder which has scales of reading the tensile stress. These components are coupled by a threaded spindle at the top end which is fitted with a hand wheel. A pin prevents the cylinder from turning relative to the housing. When the parts are screwed together the spring generates a force. The cylinder is pressed into the housing taking a pointer with it that holds that indicates the maximum force that was reached after the spring is released.