When wet, leather expands and when dry, it shrinks.
The consequences are as follows:

• Increase of expanded or shrink pieces of leader
  
• Crumpling and wrinkling
  
• Loss of shape of shoes, gloves, bags etc.

The change in moisture content is a result of the changes in relative air humidity. It is necessary to ensure a balance between the humidity of leather and the ambient air in order to preserve the shape and structure of the leather (the balance between moisture content in the leather and relative humidity must be maintained). In this case, the leather no longer releases or absorbs moisture. This condition is achieved only after several days of storage (drying process).

If the main factor during processing and storage of leather is the constant air humidity, the drying phase after the leather is produced or after the treatment process requires relatively high air humidity.

Recommended relative values of air humidity in the leather industry