How does cardboard become damp when water hasn’t touched it?


It has been raining a lot at work recently and I’ve noticed that all of our cardboard boxes in the storage area feel damp. Not necessarily wet, but they’ve gone soft and fall apart with much more ease. How is it that this happens if they’re stored above the wet floor and haven’t had any contact with water or rain at all?

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Cardboard and other similar virus materials are pretty good at absorbing moisture from the air. And it is very common for basements to be fairly damp and to have high humidity even if they are well drained and have no actual sitting liquid water.

> …they’ve gone soft and fall apart with much more ease.

Cardboard has a definite tested lifespan depending on conditions. Cardboard is wood, shredded and restructured/compressed. When wood fibers absorb and evaporate water they expand and contract on a micro level. It’s like hot/cold cycles that cause expansion/contraction, the wood ‘moves around’ too when fibers get wet. All that moving around weakens the micro structure, which weakens the overall material structure and strength.