Regarding the article in the June issue (The Importance of On-Going Facility Monitoring) which brought attention to what the title of the article addresses there is another, often forgotten aspect of the monitoring program, which is the witness plate sampling and counting method as described in IEST-STD-CC1246D. This standard was formerly a military standard (MIL STD 1246). Other industries wanted the same testing conducted to verify the cleanliness of their products and controlled environments. Therefore, it became an international standard for all industries. The settle-out testing via witness plates shows what size, shape, and quantity of particulate and residue is settling on the product. Airborne particulate can remain airborne for an undetermined amount of time. Thus, settle-out and airborne testing complement each other. This test was required for the military and aerospace industries. Now, it is advantageous to all industries (medical, pharmaceutical, nutriceutical, optics, injection molding, food, etc.).
The virgin witness plates are baseline scanned, double-bagged, exposed in the critical areas (exposure time TBD), sealed properly, and re-scanned via optical surface scanner, to detect the contamination. An actual graph and scan is a great visual proof of product and room cleanliness (or lack thereof). This visual proof is justification for implementing improvements, or proving product cleanliness to the customer. The “cleanliness level” per the 1246D standard, is calculated using a formula.
Witness plates are also used to test the cleanliness of new gloves. Or to determine how often the personnel should change the gloves, during use.
With the training for proper handling, witness plates can be shipped to and from the lab/customer facility. It is a win-win situation!
Ms. Barbara Done is President of Micron Management, Inc. She can be contacted at (585) 746-1859. www.micronmanagementny.com
