Coating Mass
A physical measurement quantifies the mass of dried coating material applied to a square metre of paperboard surface. This metric determines the thickness and coverage of pigment, latex, or barrier polymers on the fibrous substrate. In paper mill operations, dry coat weight gsm acts as a control value to optimize raw material usage while achieving the desired functional properties of the board.
Application Control
The thickness and uniformity of a functional layer are directly related to dry coat weight gsm. When the applied weight is below the specified target, the barrier properties against grease or water vapour are often compromised, leading to premature deterioration of the packaged product. Applying excess coating increases manufacturing costs and can make the board brittle, which leads to cracking along crease lines during the folding carton converting process.
Quality Compliance
Mill technicians monitor this parameter during the coating process using online gauges or gravimetric sheet analysis. Regular testing ensures that each batch of paperboard meets the strict performance requirements of high-speed printing and filling lines. This consistent tracking is necessary to prevent variations in ink absorption and gloss, allowing the packaging converter to maintain a uniform print quality across different production runs of the same carton design.
By recording these metrics, the paper mill can also verify compliance with customer contracts, which often specify narrow tolerances for coat weight to ensure that downstream processing occurs without requiring constant machine adjustments on the printing press.
