Paper Supply Contract Pulp Index Pass through Clause Mechanics
Paper contract pass-through clauses must weight indices to exact furnish shares and apply deadbands to prevent unearned mill margin inflation.
Multi Ply Paperboard Furnish
Fiber Recipe
Layered sheet formation in modern paperboard machines allows for the combination of different fiber types to optimize both stiffness and cost. In multi-ply paperboard manufacture, multi ply paperboard furnish refers to the specific combination of mechanical and recycled fibers used in each separate layer of the board. This tailored blend ensures that each layer is optimized for its specific function, such as providing a smooth printing surface or a bulky, stiff core.
The exact recipe is set by the mill’s product design and the requirements of the converter. The furnish is critical for determining the board’s final properties.
Layered Performance
The performance of multi-ply board is determined by how these different pulp layers interact. The outer layers are typically composed of bleached chemical hardwood or softwood pulp, which provides a bright, smooth and clean surface for high-quality graphics and protective coatings. The inner core layers use bulky mechanical pulp or recycled fibers, which provide the bulk and thickness needed to maximize the bending stiffness of the board.
By concentrating the high-strength, premium fibers on the outside and the high-bulk, cheaper fibers on the inside, the mill can produce a board that is both stiff and cost-effective. This layered structure behaves like an I-beam, where the outer flanges carry the load and the center provides the separation. This design provides maximum performance with minimum fiber weight.
Resource Optimization
Optimizing the furnish mix is an ongoing task for paper mill chemists and engineers. They must adjust the proportions of recycled and virgin fibers to match changing market availability and pricing without compromising the technical specifications of the finished board. This work requires a deep understanding of how different fiber treatments and additives affect the bonding between the layers.
The resulting boards are used for demanding retail packaging applications.