Meaning
Mineral pigments derived from natural limestone are added to paper coatings to improve brightness. The inclusion of ground calcium carbonate creates a smooth surface that enhances print quality on packaging boards. This mineral is a standard ingredient in paperboard manufacturing.
Coating Application
High-speed printing requires a receptive surface that absorbs ink uniformly without causing the colors to bleed. When applied in a surface coating, ground calcium carbonate improves the ink absorption properties and brightness of the paperboard. This improvement results in sharper image resolution and higher print gloss on the final retail box.
Economic Strategy
Fiber costs represent a significant portion of the total expense in paperboard manufacturing, pushing mills to find economical alternatives. Replacing expensive wood fibers with ground calcium carbonate reduces raw material costs while maintaining or even improving the board’s bulk and opacity. This substitution allows mills to offer competitive pricing to packaging converters while preserving their own manufacturing margins.
Purchase Term
Supply contracts between board manufacturers and mineral suppliers specify the particle size distribution and brightness of the mineral slurry. Consistency in ground calcium carbonate quality is essential because any variation can affect the coating’s viscosity and the eventual print performance of the board. The contract will usually define strict rejection limits for grit content and moisture to prevent production interruptions at the paper mill, ensuring that the final board meets the rigorous standards of commercial printers.
