Why can’t dye penetration tests be used for nonporous materials?
A method to detect channels in seals of nonporous packages as well as holes in nonporous materials is currently under development by ASTM. This method has some important differences from ASTM F1929, Standard Test Method for Detecting Seal Leaks in Porous Medical Packaging by Dye Penetration, with one of the key differences being the dye penetrant solution formulation.
The dye penetrant solution in F1929 is specifically designed to test porous materials. The dye penetrant solution will wick through the porous material. To slow this process, the surface tension of the solution is kept relatively close to the surface energy of the materials it is testing.
If this same solution is used on a nonporous package, it performs very slowly and can result in the user failing to detect holes. To address this, the surfactant level of solution used in the proposed method for nonporous materials has been increased by a factor of six. This yields a dye penetrant solution with a surface tension well below the surface energy of commonly used packaging materials.