Adhesion Rating
Standard test methods established by ASTM International classify the mechanical adhesion of organic coatings to metallic or rigid substrates following lattice cuts made through the film layer. Executing a cross-hatch pattern with a multi-blade cutter or single razor allows technicians to apply standardized pressure-sensitive tape over the scribed area before rapid removal at an angle close to one hundred eighty degrees. The resulting flaking or lattice detachment yields a scale rating from zero B to five B under ASTM D3359.
This measurement evaluates film anchorage on coated paperboard, metal tins, and rigid composite packaging. The protocol stops short of measuring absolute tensile bond stress, quantifying only visual flaking resistance under localized shear forces.
Lattice Geometry
Grid spacing selection depends directly upon dry film thickness to ensure accurate structural evaluation during testing. Coatings below fifty micrometres require one-millimetre lattice spacing, whereas thicker films up to one hundred twenty-five micrometres demand two-millimetre spacing to prevent excessive edge chipping. Cutting pressure must pierce the coating completely without gouging the underlying substrate sheet.
Pressure-sensitive tape application requires uniform rubber roller pass counts to secure consistent interfacial contact before tape pull-off. Flaking along the cut lines indicates inadequate primer wetting or incomplete UV curing on high-speed coating lines.
Coating Limit
Substrate flexibility limits evaluation repeatability because deep substrate bending under tape strain distorts lattice edges. Brittle varnish films yield lower adhesion ratings despite strong chemical bonding at the interface.
