DIN EN ISO 3379 (accredited)

Our test laboratory performs testing in accordance with DIN EN ISO 3379 using an accredited procedure. This standard describes a test method for determining the grain distension in leather using the ball burst (lastometer) method. The aim of the test is to evaluate the extensibility of the leather surface and its resistance to mechanical stretching, particularly with regard to the formation of cracks or other surface damage. These parameters are of particular importance for applications in which leather is subjected to three-dimensional deformation or significant tensile stress during use, such as in shoe uppers, upholstery leather, or automotive interior materials.

During the test, a circular specimen is cut from the leather and clamped around its edge in a test fixture. The specimen is then expanded from the reverse side by a hemispherical plunger or steel ball. During loading, both the surface distension and the corresponding applied force are continuously recorded. The test is continued until the first cracks or other permanent damage appear on the grain side of the leather. In addition, the distension at burst (until complete rupture of the material) may also be determined.