Flex tester for upper Sole

crack or otherwise fail at flexing creases, but can also be used to assess whether leathers are likely to produce salt spue. In particular, the test simulates conditions in the vamp part of footwear during walking. The test can be conducted with either wet or dry specimens at room temperature. The method is applicable to all flexible materials and in particular those used to manufacture outers and linings of footwear uppers such as leathers, coated fabrics and textiles.

Principle

A square specimen of the material is folded over two inverted V-shaped clamps. The clamps are able to move relative to one another so that as they become closer the specimen is flexed to produce one downward crease surrounded by four upward creases. During the test, the clamps oscillate at a constant speed so that the specimen is repeatedly flexed. After a predetermined number of cycles, the test is stopped and the specimen is visually examined for signs of damage or salt square.