ISO 3379 Leather - Standard Test for Determination of Surface Swelling and Strength

EUROLAB, together with its state-of-the-art accredited laboratories and expert team, provides precise and fast testing services within the scope of ISO 3379 testing. ISO 3379 specifies a test method for determining the tensile and strength of the leather grain or finished surface. This method is applicable to all supple leathers and is particularly suitable for determining the durability of leathers for shoe uppers.

A circular test piece is clamped around its edge, and a steel metal ball attached to the tip of a piston is gradually inflated by forcing it toward the center of the test piece on the back. At a given stress, measured in terms of distance traveled by the piston, the wear surface of the test piece will develop cracks or cause other permanent physical damage; this expansion is recorded as the crack point or initial damage. At a higher expansion, the material usually bursts and this expansion can also be recorded.

Patent leather is a special case because often the grain of the skin cracks before the patented surface film. Therefore, special care is required when examining patent leather test pieces. Two signs of grain cracking are a small shallow depression in the film surface above the crack and a momentary decrease in force on the piston. If the patent film cracks, it will be considered a "grain crack" whether or not cracks are visible in the grain.

For some leathers, it is possible to identify grain or final cracks in the wear surface by analyzing the force-displacement curve. When cracking occurs, there is a sudden reduction in load, which should only be considered a confirmation of visual assessment.

If there is a pause during stretching of a test piece, the stresses inside it relax and the force reading tends to drop. Therefore, the test is ideally continuous with no delay, but if necessary, any delay in the stretching between cracking and bursting is less than 15 seconds.

EUROLAB assists manufacturers with ISO 3379 test compliance. Our test experts, with their professional working mission and principles, provide you, our manufacturers and suppliers, the best service and controlled testing process in our laboratories. Thanks to these services, businesses receive more effective, high-performance and quality testing services and provide safe, fast and uninterrupted service to their customers.