**7.8 Folding endurance**

Folding endurance is another method for determining a film's mechanical qualities. It's calculated by folding a film at the same location over and over until it breaks. The number of times the film can be folded without breaking is known as the folding endurance value. A film with a higher folding endurance rating has better mechanical strength. The mechanical strength of films and their folding durability are inextricably linked. Because plasticiser concentration influences mechanical strength, it is apparent that plasticiser concentration also has an indirect effect on folding endurance.
