Fillers go into the sheet and coatings go onto it, and both are mineral problems before they are paper problems.
The practical challenge is rheological. A coating colour has to carry as much solid as possible while staying fluid enough to meter evenly at machine speed — which is a dispersion question.
What we supply
Kaolin, Calcium Carbonate (Light), Sodium Hexametaphosphate and Sodium Tripolyphosphate.
What we supply
KaolinCalcium Carbonate (Light)Sodium HexametaphosphateSodium Tripolyphosphate
Kaolin Its platy particles lie flat on the sheet, giving the smooth, closed surface that print quality and gloss depend on.
Calcium carbonate Brightness and bulk at filler economics — it displaces fibre, which is the cheapest legitimate way to make a sheet.
Dispersants Coating colour runs at high solids and low viscosity, an inherently unstable combination. Phosphate dispersants keep the particles apart so the slip stays pumpable.