This practice is valuable in determining the resistance of flexible-packaging materials to flex-formed pinhole failures. Conditioning levels A, B, or C are typically used for this evaluation.

This practice is valuable for determining the effect of flexing on barrier properties such as gas and/or moisture transmission rates. Conditioning levels D or E are typically used for this evaluation.

This practice does not measure any abrasion component relating to flex failure.

Failures in the integrity of one or more of the plies of a multi-ply structure may require different testing than the detection of holes completely through the structure. Permeation tests using gas or water vapor can be used in conjunction with the flex test to measure the loss of ply integrity. However, any permeation test requiring a pressure differential will not measure the permeation coefficient in the presence of pinholes. For a list of test methods refer to Guide F2097.

The various conditions described in this procedure are to prevent testing a structure under conditions that either give too many holes to effectively count (normally greater than 50), or too few to be significant (normally less than five per sample). Material structure, purpose for testing and a mutual agreement between parties involved are important points to consider in the selection of conditioning level for testing.