Substrate Composition
Recycled fibre multi-ply folding boxboard consists of a bleached virgin top layer paired with recovered cellulose fibres in the middle and back plies. Gd2 recycled board offers a printing surface treated with a double coating on the top side to maintain high opacity and brightness during high-speed offset lithography. Mechanical properties rely on the specific grammage of the middle layers which dictates the stiffness and compression strength of the finished packaging.
Consistent fibre orientation across the web improves the runnability of this material on modern high-speed folding and gluing machinery. Moisture resistance depends on the internal sizing additives applied during the papermaking stage to prevent liquid penetration into the porous recycled core.
Manufacturing Process
Paper mills utilize a wet-end formation process to stack distinct layers of furnish onto the forming wire before the consolidation of the sheet. Gd2 recycled board incorporates a grey back or cream back recycled pulp to reduce production costs while retaining a white printing face. Drying cylinders evaporate water from the consolidated web while calendar rolls compact the sheet surface to achieve a specific thickness and smoothness.
Control of the coating weight applied by the air knife or blade station defines the ink holdout and gloss finish of the board. Precise tension control during the winding stage ensures that the roll diameter remains uniform across the entire length of the production run.
Dimensional Stability
Variations in humidity within a print shop or conversion facility influence the moisture content of the cellulose fibres inside the sheet. Gd2 recycled board exhibits linear expansion when the ambient moisture increases which potentially disrupts register accuracy on a multi-colour printing press. Manufacturers set a tolerance for moisture content in the mill that corresponds to standard shipping and storage environments.
Fibre expansion causes slight curling when one side of the board gains more moisture than the other. Proper storage in a climate controlled environment remains the method to keep the substrate flat for automated handling systems. High consistency in density and caliper ensures the substrate performs reliably under the physical stress of die cutting operations.
