This test method is valuable in determining the resistance of flexible-packaging materials to flex-formed pinhole failures.

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

Physical holes completely through the structure are the only failures measured by the colored-turpentine-pinhole portion of this test. Failures in the integrity of one of the plies of a multi-ply structure will not be determined by the colored-turpentine test. Gas permeation or moisture vapor transmission tests, or both, 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.

4.3.1 The various conditions described in this procedure are to prevent testing a structure under conditions that either give too many holes to effectively count and be significant (normally greater than 50), or too few to be significant (normally less than five per sample).

Measurements on nylon film, possibly because of its hydrophilic nature, have not shown good reproducibility (between laboratories), although the repeatability of the data within a laboratory was good.