Surface Evaluation
Standardized adhesive sticks measure the internal bond strength and surface pick resistance of coated paperboard substrates. A dennison wax pick test applies calibrated hard wax sticks heated to melting point against the sheet surface before rapid manual pulling. The highest wax number that pulls clean without disrupting surface fibers or pulling off coating defines the pick rating.
Adhesive Resistance
Offset printing inks generate high viscous tacky forces that pull against paperboard coatings during rapid impression cycles. The dennison wax pick rating determines whether paperboard withstands high-tack inks without surface picking or blistering. Wax sticks with increasing numerical designations exert progressively higher adhesive pull forces upon cooling.
Lower pick values indicate weak surface sizing or poor clay coating binder cohesion, leading to ink blanket contamination during printing. Higher wax numbers confirm that surface fibers resist delamination under heavy ink coverage. Modern offset lithography on coated folding boxboard typically requires a wax pick rating of eleven or higher to prevent surface picking.
Coating Boundary
Wax testing evaluates surface ply strength under dry room temperature conditions. The dennison wax pick method does not apply to plastic films, extruded barrier layers, or wet-strength treated wet-end sheets. Testing halts when thermoplastic surface coatings melt upon contact with heated wax.
The test result fails to predict wet pick performance on damp offset press dampening units.
