Crumpling device specially used for banknote testing.
The NBS crumpling device consists of an apparatus for rolling the paper sample and a device in which the rolled paper is crumpled under a fixed pressure (100 N).
When paper is crumpled the interlaced fibres are disturbed, the bonds are loosened, and the disarranged structure becomes less compact, weaker and more permeable to air.
The effect of the crumpling treatment is measured by the change in air permeability (porosity), water absorption and/or in tensile strength.
The properties of the paper before and after crumpling are measured on identical paper samples.