Until recently, there was one method using dye to test for seal leaks in porous medical packaging. Now there are three methods manufacturers can select from for their product’s packaging. Which one should be used and why? This article attempts to tackle that question.

ASTM F1929-12, Method A with test specimen being injected with dye solutionASTM recently announced a significant update to ASTM F1929-12 “Standard Test Method for Detecting Seal Leaks in Porous Medical Packaging by Dye Penetration.” The standard, ASTM F1929, was first written in 1998 and was reapproved in 2004. The update to the standard marks the first significant change in the past few years. Cited by ISO 11607-1 as a method to test package integrity, F1929 is a dye penetrate integrity test used by package engineers that is designed to detect and locate leaks caused by channels formed between a transparent film and a porous material.

The update results in three different dye application methods. In the past, the only option was by injection (Method A) where the dye solution was exposed to the seal from the inside of the package. With this revision, however, two new test methods have been developed—edge dip (Method B) and the eye dropper (Method C). These two new methods give manufacturers an opportunity to perform dye leak testing without exposing the product to a significant amount of dye, causing less mess and using less dye. The two new methods evaluate package seals by using dye solutions that are applied from the outside of the package, seeking out any channels in seals where capillary action is the force that pulls the solution into the package.

Part of ASTM’s revision process for F1929 included an interlaboratory study in which DDL contributed. DDL has conducted package integrity tests for over 20 years and recommends the use of Method A due to its consistency and applicability to more package designs. Although the company is able to perform all three test methods, ultimately, it is a customer’s decision as to which method they’d prefer to use. Following are descriptions of the various methods that can be considered when choosing a method for evaluating a sealed package.

A laboratory technician tests a pouch to ASTM F1929-12, Method A where the dye solution has been injected into the pouch.Method A—Injection
The injection method involves injecting dye into the package covering the longest edge with a depth of approximately 0.25 inches of dye. The dye is allowed to contact the sealed edge for a maximum of five seconds and a channel would be detected within this time, if present. The package is then rotated in order to expose the dye to the remaining sides of the package.

Method B—Edge Dip
This method is performed by dipping the package into a container filled with dye, exposing the entire seal edge to the dye solution so that it briefly contacts the dye along the entire length of the seal, just long enough to wet the edge. The package is then removed and inspected for channels. This method exposes the exterior of the package to the dye in order to detect channels. The edge dip method may be preferred because needles or syringes are not used and is faster to perform.

Method C—Eye Dropper
The eye dropper method involves using an eye dropper to apply dye along the edge of the package seal between the transparent and porous materials. Method C requires packages to have excess material along the outside of the seal to contain the dye. As in method B, channels are detected from the exterior to the interior of the package. The channel, if present, will manifest itself in the same way as Methods A and B—through capillary action.

Dye penetration testing is considered a destructive test where the test specimen is not recoverable after testing. Further, device manufacturers should be aware that the product protected by the packaging may be adversely affected by exposure to the dye solution.