Equalization Process
Moisture equalization represents the process of exposing packaging materials to standard atmospheric conditions to stabilize their water content before converting or printing. Utilizing paperboard conditioning prevents physical distortions like curling or dimensional changes that occur when dry board absorbs moisture from the pressroom air. The process is complete when the internal temperature and humidity of the paperboard pallet match the ambient conditions of the production floor.
This uniform state reduces internal stresses within the cellulose fibers.
Ambient Exposure
Pallets of paperboard are left in the pressroom or a dedicated conditioning zone with their protective plastic wrap intact for a specified period, which can range from twenty-four to forty-eight hours. If the wrap is removed too early while the board is still colder than the room, condensation will form on the edges, leading to sheet distortion. The rate of temperature equalization depends on the size of the pallet and the temperature difference between the storage area and the pressroom.
Utilizing a probe hygrometer confirms when the internal core of the pile has reached equilibrium with the room before the protective packaging is stripped away.
Mechanical Benefit
Sheets that have been conditioned feed smoothly through the high-speed vacuum separators of modern printing presses. This prevents double-sheet feeding, misregister, and jam-related downtime that can disrupt high-volume packaging runs. Flat, stable sheets also ensure uniform contact with the printing plate, which leads to consistent ink transfer.
