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 (a) comparing between or among laboratory results (for example, supplier and customer), (b) temperature or humidity is anticipated to have an effect on the test outcomes, or (c) potential sources of variation in test results must be minimized.

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.

This specification defines the standard temperature and humidity for conditioning and testing of materials at nominally ambient conditions. Materials for conditioning and testing include material containing paper and plastic material. The instruments and techniques used to measure these standard conditions of temperature and humidity must be validated.