Cleanroom Wiper Testing: Good News and a Little Guidance

Wipers are necessary to cleaning any cleanroom, but they need to be tested to ensure they’re non-linting. Here is some information as well as good news on testing.

Wiper-based cleaning is one of the most effective methods of cleanroom cleaning. Test data to confirm that wipers are non-linting is a USP 797 requirement. However, there is no recognized test, procedure, or recommended practice that will determine the right wiper for a specific cleanroom, process, or activity. So what do you need to know about finding the right wiper?

There is a recommended practice for determining wiper contamination characteristics, so this is a good place to start. These are found in the IEST-RP-CC004.3, Evaluating Wiping Materials Used in Cleanrooms and Other Controlled Environments.  Here you’ll find descriptions of contamination characteristics and contamination levels like:

  • Particle
  • Fiber
  • Non-speciated extractable matter
  • Ionic contaminant

In addition to these factors, however, are those aspects that are difficult to quantify, like:

  • User process needs
  • Impact of activities (cleaning spills and surfaces, holding manufactured parts and pieces, etc.)
  • Impact to product yield
  • Impact to manufacturing costs

All of these elements factor into what will provide the most appropriate cleaning and contamination control. So when it comes to testing and documenting, how do you know what type of wiper to start with? Here are three considerations for choosing the wipers to test:

  1. Wipers used in ISO Class 3-4 cleanrooms are usually knit polyester with edges that are most likely sealed but can be cut if the durability process allows it.
  2. Wipers used in ISO Class 5-8 are usually nonwoven polyester/cellulose.
  3. Both contamination and performance characteristics, like sorption capacity and rate, impact selection decision. Sorption capacity = amount of liquid a wipe can hold; sorption rate = how fast a wiper can sorb liquid. Your particular needs are based on your cleaning solvent/solution and protocol.

While validating wipers without a definite test or guideline is frustrating, there is good news. A group of wiper manufacturer industry experts, cleanroom consumable distributors, and end-users of wipers are making headway. This group is the IEST’s Working Group 4, and they are revising the recommended practice: Evaluating Wiping Materials Used in Cleanrooms and other Controlled Environments. Part of their revision is dedicated to standardizing the test methods used to evaluate wipers.

If you need cleanroom validation or certification, or you have questions about either process, call Gerbig Engineering Company. We perform these services as well as manufacture cleanrooms. Contact us at 888-628-0056 or