Humidity has a significant influence on corrugated cardboard. In case of a high humidity, the strength of the cardboard, and, therefore, your packaging, may reduce by 50%.
The amount of moisture absorption depends on the composition of the cardboard. Via a determination of the humidity level in cardboard in case of humid (90% RH) and dry (105 °C) circumstances, the percentage of moisture absorption can be determined.
This test is conducted according to test standard ISO 287.