ASTM E171/E171M-11(2020)

4.1 Conditioning is used to minimize the variation in test results that may result from fluctuations in temperature and humidity, or both. Many flexible packaging materials or components of flexible packaging materials, particularly materials that are hygroscopic, undergo changes in physical properties as the temperature and the relative humidity (RH) to which they are exposed are varied.

4.2 Many packaging materials do not exhibit a meaningful change in physical properties across the temperature and humidity range that is generally found in office and general laboratory settings. As a result, conditioning of samples is often not required in order to achieve useful test results and is often bypassed during routine testing.

4.3 Conditioning should be considered when 4.4 Temperature and humidity alone are not sufficient to completely define a storage condition. Many other factors may be relevant (such as time, light, and atmospheric pressure) that are not defined in this specification.

1.1 This practice defines the standard temperature and humidity for conditioning and testing of flexible barrier packaging and flexible barrier packaging materials at nominally ambient conditions.

1.2 There are many other temperature and humidity conditions that may be appropriately used to test end use conditions (such as freezer, refrigerated, or abusive storage). These need to be individually established and are not in the scope of this practice.

1.3 Only those materials that fall under the general area of flexible barrier packaging materials are included in this practice.

1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.