Understanding Chemical Permeation Testing

Last week the ASK GIA blog talked a bit about the correlation between glove thickness and safety. We briefly dismantled a few myths about this relationship. Usually, most customers’ first criteria and feature when choosing gloves is glove thickness. However, it does not always offer better hand protection. It’s important to note other qualities of a glove and confirm that the glove is appropriate for the specific workplace environment. According to the US Bureau of Labor Statistics, there were 16,550 nonfatal burns that occurred in the workplace in 2020 and at least 3,540 were related to chemical burns or corrosions. If the workplace involves the use of chemicals, it’s important to observe the chemical permeation and degradation times of the glove material.

Chemical permeation is the amount of time until a chemical passes through the glove material at a molecular level. Degradation is any change to the physical properties of the glove due to continuous contact with certain chemicals. Degradation usually manifests as discoloration, swelling, shrinking or even cracking of the glove. While degradation is usually the first visible sign of glove failure, even if there are no visible signs of degradation, it is not a guaranteed assurance of glove performance. A glove can fail even before there are signs of degradation. It’s important to note the permeation and breakthrough times of different gloves. Breakthrough time is the measurement that takes a chemical to penetrate the material from the outside of the glove to the inner lining. Once the breakthrough time has elapsed, the glove is no longer providing adequate protection for the user.

 

How do we measure a strong, chemical resistant glove? What are the standards for testing chemical permeation and degradation?

Chemically resistant gloves are tested against ANSI-ISEA (American National Standards Institute, International Safety Equipment Association) and EN (European Committee for Standardization) standards. The ASK GIA blog has discussed other glove standards administered by these two organizations before, such as Cut and Abrasion levels. The specific guidelines for chemical resistant gloves fall under ANSI-ISEA 105 and EN374-3 Standards. ANSI-ISEA 105 and EN374-3 Standards follow ASTM F739-12 (American Society for Testing and Materials) standardized testing procedures. The one major difference is EN 374 now measures a glove’s degradation in the presence of chemicals. EN 374 specifically measures the puncture resistance of the glove material before and after continuous contact of the external surface with a chemical. The other difference between ANSI-ISEA 105 and EN374-3 is the labeling of breakthrough limits.

ANSI-SEA breakthrough times are categorized by 7 levels, ordered from 0 to 6. At level 0, the breakthrough time is measured to be less than 10 minutes. Level 1 measures breakthrough time greater than 10 minutes, level 2 measures breakthrough time greater than 30 minutes, level 3 measures breakthrough time greater than 60 minutes, level 4 measures breakthrough time greater than 120 minutes (2hrs), level 5 measures breakthrough time greater than 240 minutes (4hrs), and level 6 measures breakthrough time greater than 480 minutes (8hrs).

 

EN 374 has grouped breakthrough times into 3 groups instead of individual numbered levels. They are broken down into A, B, or C. Type A denotes that the glove has a permeation resistance of at least 30 minutes each for at least 6 test chemicals. Type B denotes that the glove has a permeation resistance of at least 30 minutes each for at least 3 test chemicals. Type C denotes that the glove has a permeation resistance of at least 10 minutes each for at least 1 test chemical. There are also 18 different commonly tested chemicals that EN 374 tests for. The EN 374 label will include the breakthrough time category the glove falls under and list the specific chemicals that the breakthrough time applies to. Those in group A and B must list the specific chemicals but group C is not obligated to list the specific chemicals the breakthrough time applies to.

SW technology is verified by third party organizations such as the Skin Health Alliance (SHA), the FDA, and various standardization organizations like ASTM and ISO. We are compliant with all relevant testing organizations in the industry. Our technology and high quality products are always backed by scientific findings. All of SW’s gloves list their testing documentation on their individual product pages, where we provide transparency for our customers.