Unheated Warehouse Storage Impact on Multi Ply Boxboard Moisture Equilibrium
Unheated storage alters multi-ply boxboard moisture equilibrium, swelling sheet edges, reducing internal bond strength, and causing severe converting curl.
Sword Hygrometer Testing
Moisture Equilibrium
Relative humidity measurement inside a stack of cut paper sheets defines this standard procedure. Sword hygrometer testing involves inserting a specialized blade sensor between sheets to quantify the moisture content of the substrate in its current environment. Stability across the pile determines if the stock sits at the correct level to avoid curling or wavy edges during high speed printing.
Proper moisture balance prevents fiber distortion during the press run.
Sensor Calibration
Frequent validation of the metallic blade against saturated salt solutions maintains the accuracy of the readings. Technicians check the device at two distinct points to ensure the dial or digital display tracks linearly across the expected range of ambient humidity. Calibration frequency depends on the intensity of use and the environmental fluctuation within the paper storage area.
Mechanical fatigue of the delicate sensing element eventually leads to reading drift.
Production Outcome
Achieving correct equilibrium levels enables the efficient processing of coated and uncoated paper stocks through complex finishing lines. Printers monitor the material status to verify that the fiber tension remains uniform before the sheet hits the nip of the press. Excess moisture causes surface blistering when ink sets under heat, while deficient levels lead to cracking during the folding of heavy weight cover stocks.
Consistent monitoring ensures the substrate reacts predictably to mechanical stress.