Can method FPA SPMC 004, Standard Test Method for Seal Integrity Dye Penetration Method be applied to the testing of blister/lid packaging?
Dye penetration is an excellent test for evaluating the seal integrity of blister/lid packaging. The dye penetration test should be validated using samples with a known channel size. One way to accomplish this is by sealing a fine wire in one seal of the blister/lid package and, after it has cooled, removing the wire. Care should be taken to develop a dye formula with color intensity sufficient to easily observe a channel.
When using water-based dye solutions, the amount of surfactant may need to be adjusted to provide optimal results (see the test method for the recommended range of surfactant concentration). As a general rule, nonbreathable packages (e.g. films and laminates) will perform best with the concentration of surfactant at the high end of the range. Whereas, a solution with a surfactant concentration at the low end of the range is appropriate for packages with at least one porous or breathable web (e.g. paper and Tyvek®). For further reference on testing porous packages see ASTM F1929 Standard Test Method for Determining Integrity of Seals for Medical Packaging by Visual Inspection.
When using alcohol-based solutions, the alcohol choice must be compatible with the packaging material. The supplier of the packaging material can provide guidance as to the appropriate solvent choice.