Adhesion Protocol
International procedures specify a method for assessing the resistance of paint and varnish coatings to separation from substrates when a right angle lattice pattern is cut into the film. The iso 2409 standard is the global benchmark for the cross-cut test used in the print and packaging industries. It applies to both hard and soft substrates by varying the spacing of the cuts according to the thickness of the coating.
This test measures the bond strength of functional or decorative finishes.
Grading System
Testing involves making six cuts in each direction and then examining the resulting squares after brushing or using adhesive tape. A classification of zero means the edges of the cuts are completely smooth and none of the squares of the lattice are detached. At the other end of the scale, a classification of five describes any degree of flaking that cannot be classified by grade four.
The spacing between the cuts is usually one millimeter for coatings up to sixty micrometers and two millimeters for thicker layers. This precision ensures that the stress applied to the bond is consistent across different materials. Proper illumination is required to see the fine cracks in the coating surface.
Industrial Application
Quality control departments use this standard to verify that ink batches or varnishes are compatible with new paperboard grades. It provides a repeatable metric that can be cited in commercial contracts or technical specifications.
