Another reason might be that the paper absorbs moisture.

There was a question also about whether or not foam absorbs moisture.

Flour absorbs moisture from the air, and its behavior changes a lot based on how much water it has absorbed.

They are less likely to dry out because the honey absorbs moisture from the surrounding air.

Thus it is capable of absorbing both moisture and oils.

It can absorb excess moisture, which may come from sweating.

If you must wear these, choose the kind with a cotton panel to absorb moisture away from your body.

I have trouble believing that rice is more likely to absorb moisture in the air than table salt.

Wool can absorb moisture almost one-third of its own weight.

Due to the rock's high ability to absorb moisture, earthflows are common.