Fibre Caliper
Heavy substrate engineering establishes packaging paperboard through multi-ply cylinder machine forming where distinct stock layers share mechanical loads under controlled wet pressing. Virgin bleached kraft pulp dominates top liner layers for high brightness printability while recycled unbleached furnishes build interior stiffness at lower raw material costs. Caliper tolerance variation across the web width dictates subsequent folding carton crease formation without surface cracking during high speed converting operations.
Crease Resistance
Folding endurance relies on internal ply bond strength and hemicellulose hydration levels achieved during mechanical refining stages prior to sheet formation. Bending stiffness scales proportionally with the cube of caliper dimensions making thickness optimization critical for structural carton integrity under vertical stacking loads. Rotary die cutting stations demand consistent moisture profiles to prevent delamination when creasing rules penetrate the multi-ply matrix at high operating velocities.
Barrier Coating
Aqueous dispersion applications apply functional topcoats onto the dried substrate to restrict moisture vapour transmission and grease migration without interfering with subsequent repulping recyclability. Polymer emulsion formulations cure under infrared heating zones to form continuous films that withstand hot wire sealing in automated packaging lines. Laboratory Cobb testing quantifies water absorption rates over standardized time intervals to verify surface sizing efficiency before commercial carton distribution.
