Cleanroom Gloves and Pinholes

Cleanroom and controlled environments have unique glove requirements.  While healthcare workers primarily wear gloves to protect themselves from bloodborne pathogens, a person working in a clean manufacturing environment primarily wears gloves to protect the product or process from contamination.

Pinholes in gloves provide a path for human-borne contaminants in the clean manufacturing environment.   Just one square inch of the surface of a person’s hand can contain 10,000 microorganisms!

So how common are pinholes in cleanroom gloves?

A study published in May 2011, Integrity of Disposable Nitrile Exam Gloves Exposed to Simulated Movement,  compared cleanroom nitrile gloves to medical-grade, low-modulus and general duty nitrile gloves.  A total of thirty different glove products were tested, including six cleanroom and nine medical-grade nitrile glove products.  A modified water-leak test was used to detect a 0.15 to 0.05 mm hole in different areas of the glove, including the thumb and pinky.  What did they discover?

“The cleanroom gloves, on average, had the highest percentage of leaks, and 50% failed the water-leak test.”

Two of the cleanroom nitrile gloves tested had an out of the box failure rate of 6.25%.  The medical grade and low modulus gloves had the lowest percentage of leaks.  Even the general duty gloves performed better than the cleanroom gloves tested.   However, two of the six cleanroom gloves tested had a failure rate of zero percent.  Why such a significant difference?

The study authors indicate that it could be due to differences in nitrile material formulation.  A low-modulus nitrile glove with a higher percentage of plasticizer, which is more water resistant, was expected to perform better in the water leak test.

What was not discussed in the paper is the AQL, or Acceptable Quality Level, of the gloves tested.  The AQL for the water leak test, a test that indicates what percentage of the gloves can fail a water test for pinholes, is set by ASTM at 2.5% for cleanroom gloves.  Many manufacturers, however, use the medical grade requirement of 1.5%.  This means that less than 1.5% of the gloves from any given lot could fail due to pinholes – substantially less than 2.5%.

Clearly, there are significant differences in the quality of cleanroom gloves on the market.  To protect your cleanroom environment, select cleanroom gloves made from consistently high quality low-modulus NBR materials, and an AQL of 1.5% or less.

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