Moisture Regain between Mill Conditioning and an Unheated Warehouse
Unheated storage drives moisture ingress along sheet edges via psychrometric gradients, requiring sealed barrier wraps and strict thermal acclimation before press run.
Polyethylene Wrapper
Moisture Protection
Protective packaging materials in this category are used to encase finished paperboard rolls or sheets to protect them from environmental moisture and physical damage. The polyethylene wrapper acts as a barrier against water vapor and dust during transit and storage. This protection ensures that the paperboard maintains its specified moisture content and flat profile until it reaches the pressroom.
Barrier Sealing
Packaging involves wrapping the finished rolls in a thick sheet of low density polyethylene film and sealing the ends. This process protects the edges of the roll from physical impacts and prevents moisture from entering between the layers of paperboard. Rolls with high moisture sensitivity can warp or develop tight edges if they are exposed to varying humidity.
The film must be puncture resistant to withstand handling by forklifts and clamp trucks in the warehouse.
Packaging Choice
Consistent use of this wrapper is required for export shipments and long term storage in non climate controlled areas. This material does not apply to internal transport within the same manufacturing plant where environmental exposure is minimal. Releasing the wrap must only be done shortly before printing to prevent the board from acclimating to pressroom humidity too quickly.
The wrapper is fully recyclable and is typically removed and baled for recycling at the converting plant.