Paper Moisture Meter

How to Check Moisture Content to Prevent Paper Warping and Degradation

After manufacturing or being introduced into a warehouse environment, paper may feel dry on the outside, but the core of the stack or roll can still retain moisture. When the moisture content remains high, the paper is prone to curling/warping (curling/warping at the edges), which reduces print quality and poses a risk of mold growth in the storage facility (warehouse mold).

For accurate measurement, it is necessary to measure the moisture content in the core of large paper stacks or rolls using a device with deep-penetrating pins or a specialized sensor. DELMHORST models are suitable because they provide fast and stable results.

What is the Safe Moisture Content for Storing Printing Paper and Cardboard?

Paper and other printing materials need to have a moisture content between 4–6% for long-term storage. If this level is exceeded, the paper is easily deformed and damaged when stacked high. Before warehousing, it is necessary to measure multiple points in different locations within each package to ensure the entire batch of paper has dried uniformly. When the required level is achieved, the paper maintains its print quality for a long time and minimizes the growth of fungus or mold.

Why Paper Can Easily Develop Mold Even If It Looks Dry on the Surface

Paper has a fibrous structure that retains moisture internally. The surface may be dry, but the core has not fully released the water vapor. When placed in a warehouse or packed into bales/rolls, this moisture is trapped and creates conditions for mold to develop. Therefore, relying on visual assessment is insufficient, and moisture measurement is required to determine the exact condition inside the material.

Reference equipment at: EMIN Paper Moisture Meters

Why Relying on Sensory Measurement Is Prone to Error When Purchasing Large Quantities

When purchasing large volumes, the moisture content between the outer and inner layers of the paper stack or roll can vary significantly. Checking by hand or by experience only reflects the outer layer and cannot assess the material deep inside. Even a small discrepancy can reduce the value or cause damage during storage and printing. Therefore, using a measuring device is an essential solution to ensure accuracy and avoid disputes during goods handover.

Procedure for Processing and Checking Moisture Content to Minimize Loss in Printing/Storage

When processing paper, it must be ensured that the paper has reached equilibrium with the warehouse environment. After fabrication (processing), the paper must be allowed to cool before being packaged or baled to prevent the trapping of heat and water vapor. Before warehousing or feeding into a printing press, the moisture content of each package must be measured at multiple points. If a portion does not meet the threshold, further treatment is required (e.g., cooling, drying) to bring the entire batch to a safe level. This procedure helps stabilize quality and reduces the risk of paper jams and deformation throughout the entire usage process.

These are the core reasons explaining why checking the moisture content with specialized equipment is crucial for paper, as well as for other agricultural products. Ensuring moisture is within the safe range will help the paper achieve the best print quality, avoid equipment damage, and is a measure to protect assets from mold and degradation during long-term storage.