Two new test developments from SATRA...

SATRA experts have devised a new strength test for leather that provides as much information about its physical properties using a single test piece as previously when it took two different tests and four separate test pieces! This means that SATRA's member companies can get the result of tests on their leathers much faster and at a lower price. Tear strength and tensile properties are critical to leather's performance in products such as footwear and leathergoods. However, because the properties of the leather hide are directional, conventional tests have to be carried out on test pieces cut in different directions. Called the Starburst test - after the eight-armed cut created in the circular test piece - the new test is multi-directional. Clamped around its outer edge, a steel ball is forced up against the back (flesh) surface until the sample ruptures in the weakest direction. Measurement of both maximum force and movement of the steel ball provide data which previously required both tensile and tear tests to be undertaken, each in two directions. SATRA assistant director Peter Perkins says: 'We are very excited about the potential for Starburst. It provides a major advantage as fewer samples need be tested and SATRA members will get their results faster. 'This new test is just the latest in a long line of SATRA developments - providing modern methods for assuring product performance.' * SATRA can also now produce faster test results for its members after developing a new process that accelerates pre-test conditioning for test samples. Experts at the UK technology centre can now achieve a conditioned state on some materials in a few hours - as opposed to the standard two days - and accuracy of the results is not affected. The level of moisture in leathers and other natural materials can significantly affect their physical properties. If the moisture content in a sample is increased, its grain crack resistance could also increase. Moisture content depends on the temperature and moisture content of the atmosphere in which it is stored. So, depending on storage history, a leather test sample could be abnormally dry or abnormally wet — or anywhere between. Testing without conditioning could create misleading results if storage history is unknown. Standard conditioning involves 48 hours of exposure in an atmosphere of 20°C, 65% rh, for leather type materials. As a result it has been impossible to obtain results within two days of receipt. The new procedure involves drying samples in an oven at 40°C for one hour. Then they are allowed to condition at 20°C, 65% rh, for a minimum of five hours. SATRA used the method on a range of leathers and found that, providing the samples were less than 2.5mm in substance, they achieved a moisture content consistent with that of 48 hours of normal conditioning. The new procedure is called SATRA TM279. Its introduction now means samples can be tested the day after receipt or - if they arrive early enough - on the same day.