Fiber Quality
Cellulose material produced by the mechanical grinding of short-fiber deciduous trees offers a specific blend of opacity and surface smoothness for printing substrates. Hardwood mechanical pulp consists of short, stiff fibers that fill the gaps in the paperboard sheet to create a uniform, closed surface. This composition makes the board highly printable, though it has lower tear resistance than softwood chemical pulps.
Print Performance
The shorter fibers of aspen or birch distribute evenly across the forming wire, minimizing the flocking that often disrupts the formation of long-fiber sheets. When used in the outer plies of multi-ply cartonboard, this material provides a uniform bed for clay coatings and graphic inks. It yields a sheet that resists show-through, allowing designers to use lighter grammages without compromising the visual appearance of the packaging graphics.
Bulk Creation
Because mechanical grinding retains the natural lignin within the wood fibers, the resulting pulp retains high bulk and rigidity under compressive loads. This bulky nature allows cartonboard manufacturers to build thick, lightweight middle layers that keep the packaging structurally stable during distribution. The lignin-rich fibers do not collapse easily, acting as stiff micro-struts that maintain the caliper of the board even when it is subjected to the tension of web-fed printing presses and folding-box converting lines, which helps the board resist the crushing pressure of the calendering process and maintains the structural strength of the box.
