Folding endurance (Schopper)
Der Falzwiderstand ist eine bedeutende Eigenschaft von Papierprodukten, welche häufig in Benutzung sind wie Karten oder Geldscheine.
The test is carried out with a twin fold tester of the Schopper method according to ISO 5626. 10 strips each are tested in longitudinal and transverse direction. The 15 mm wide strips are clamped at both ends in the testing device and tensioned with a defined tensile force. The test strip is folded to both sides by almost 180° until it tears. The number of double folds that a paper strip undergoes until it tears is noted. A double fold is a complete oscillation of the test piece while the strip is folded back and forth at the identical point. The folding resistance is calculated using the number of double folds according to the following formula:
Fold resistance = log10 (number of double folds)