Coating Density
The mass of dry material applied per unit area of paper substrate defines the thickness and coverage of a functional layer. Quality control teams rely on dry coat weight to verify the barriers, release agents, or print receptors applied to cartonboard. It represents the solid material remaining after all water or solvent carrier has evaporated during the drying phase.
Application Control
Mill operators determine this value by weighing a sample of known area before and after removing the coating, or by measuring the wet coating delivery rate alongside line speed. Wet application methods must adjust for the solids content of the slurry to achieve the targeted dry thickness. In a typical folding carton board run, an applicator roll deposits a precise wet volume that translates to the required dry mass after passing through infrared dryer banks.
If the dried layer falls below the specified threshold, the paperboard fails to resist water vapour or grease penetration during subsequent storage.
Performance Limit
Barrier integrity remains dependent on uniform coverage across the entire surface of the web. Surface roughness on the base board can cause localized thinning of the dried layer, creating pinholes where liquids might leak through. The measurement is expressed in grams per square metre, ensuring that converters can balance raw material consumption against functional performance on high-speed filling lines.
