Mass Ratio
Physical measurements that express the total mass of paper or paperboard per unit of total volume including internal air spaces quantify spatial packing efficiency. Evaluating bulk density reveals how structural pore volume affects stiffness, opacity, and liquid absorption in packaging materials. The value is calculated by dividing grammage by thickness measured under standardized platen pressure.
Application of this physical property ceases when materials undergo complete destruction of internal pore structures under extreme mechanical crushing.
Structural Density
Fibre refining alters internal volume by collapsing tubular wood cells and increasing web consolidation during wet pressing. High bulk density products contain densely packed fibres that maximize inter-fibre bonding and tensile strength while reducing overall sheet thickness. Softwood fibres preserve internal void space, yielding bulky boards that provide high bending stiffness at lower basis weights.
Papermaking operations balance mechanical beating energy against sheet density targets to optimize raw material usage.
Packaging Yield
Yield calculations in boxboard conversion depend directly on volume metrics because higher bulk yields thicker board at constant weight. Material consumption decreases when low-density boards achieve required creasing and stacking resistance without adding fibre mass. Flute structures in corrugated board rely on maintained bulk to withstand top-to-bottom compression forces during transit.
