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June 12, 2020 | Posted by MICRO
Strong, precise, adaptable, but also fragile – hands are our number one tool. Workers’ hands, however, are exposed to all manner of hazards on the work site. Proper protection is a must.
Technology to the rescue!
There are a variety of rigorously tested and rated glove materials being created and combined in innovative ways to meet the demands of different kinds of work. The right pair of work gloves can mean the difference between an “oops” and a severe injury, but with so many types available it isn’t always easy to figure out exactly what type of glove you need for what type of work.
Trying to understand the rating systems can be a little daunting. With materials types and trade names, ratings and brands, things can get out of hand. This general overview of what it all means is meant to help you navigate the vast selection of safety gloves available on the market.
Hazards to the Hands Need to Be Taken Seriously
Sometimes your task finds you working with sharp edges like tools and blades, jagged edges, or cut-off material like swarf in machine shops. Lacerations on hands are so common that cut-resistant gloves have become an increasingly standard requirement on work sites.
The Department of Labor reports that cuts to hands or fingers are the second most common type of reported injury (back is still king). Hand injuries accounted for 23% of injuries reported, and OSHA estimates that 70% of those injured were not using gloves, while the remaining 30% had inadequate gloves.
These aren’t trivial numbers. They add up to hundreds of thousands of incidents. So knowing how to select proper gloves is imperative.
Designs and materials are many and varied, with some gloves uniquely designed for specific, individual tasks. For example, those working with certain chemicals may choose butyl gloves over latex or nitrile for their lower chemical reactivity.
Most workers, however, don’t have such prescriptive tasks and need gloves that can protect their hands in a range of situations. General purpose protective gloves are usually made of a tough fiber with a good cut resistance and a gripping surface that is also resistant to chemicals and moisture. Lacerations are the main category of injury, but what about punctures, abrasions, chemical burns, and heat burns? ANSI has you covered.
The American National Standards Institute (ANSI) and the International Safety Equipment Association (ISEA) standard 105 lays out guidelines for how gloves should resist abrasion, cutting, tearing, and puncturing. and lays out a framework for rating gloves according to performance.
Using the American Society for Testing and Materials (ASTM) F2292-15 standard test method, a tomodynamometer (TDM-100) uses a straight blade and side-to-side cut to measure material resistance to a controlled cutting action at variable pressure. Based on the performance in this test (i.e. the weight load needed to cut through), an ANSI cut score of A1-A9 is assigned to the material.
The European standard EN388, although similar, uses a slightly different approach called a coupe test. A progressively weighted rotating blade is applied to fabric until it breaks through and determines the force needed.
This method has a weakness, however. If the test material is sufficiently resistant, it will dull the circular blade and a specific alternate approach has to be used. In this case, the ISO 13997 test standard takes over, utilizing the same TDM-100 machine as the ANSI method. Based on the cut-through force required in Newtons, the material is given an EN388 cut resistance letter score from A-F.
Of course, cutting edges aren’t the only hand hazard we encounter on sites and the requirements aren’t one-size-fits-all. Gloves may have to resist other types of mechanical damage like puncture and abrasion, as well as chemical permeation and degradation, heat and flame resistance, vibration resistance… the list goes on. ASTM has devised and standardized test methods for each resistance criteria, so an informed selection can be made based on the identified hazards of the work in question.
A given worker might be exposed to chemicals but no sharps. Depending which chemicals are in use, simple butyl rubber, nitrile, or neoprene gloves may work well. Other workers may not work with many chemicals at all but protection from vibration or abrasion may be especially important. Workers may spend a lot of time outdoors, where protection from the cold is more relevant than heat resistance. The needs vary drastically from one application to the next.
Whatever your work has you doing, thoughtful selection of gloves can help ensure tasks with novel hazards aren’t putting hands at risk. For example, a 2016 addendum to the 105 standard added a test method for rating resistance to hypodermic needle puncture – an important criteria to sanitation and medical workers.
PPE selection has to consider the type of work and both ANSI and protective glove manufacturers have made an effort to be comprehensive in addressing hazard categories.
For all of the complicated ratings and measurements, none of it is any good if the gloves are too stiff and restrictive to use.
If they are too thick or coarse to allow for reasonable dexterity, you’ll see them getting removed constantly and risk adding to the 70% of hand injuries in which a worker was not wearing protection.
If gloves don’t let the worker perform their task effectively, the purpose is utterly defeated. So, while protection is a priority, they must also be made of materials that are practical. Properties like tactility, dexterity, weight, warmth, wicking, and comfort help ensure the gear will be worn, so the material they are made from is especially important.
So, what materials are today’s protective gloves made from? Ultra-high molecular weight polyethylene and similar synthetic materials are used as a liner in a number of products. It’s an extremely tough synthetic thermoplastic that can resist mechanical damage (15 times more resistant to abrasion than carbon steel!) and as a bonus, has a good resistance to acids and alkalies.
Aramid (aromatic polyamide) and Kevlar are alternative materials that make ideal glove liners due to high cut and chemical resistance and have the added benefit of being light and quick-drying.
The outer shell is the main body of the glove, and different fabrics may be layered to cater to specific needs. Synthetic or natural leather, or alternatives such as elk skin, deer skin, pig skin, or goat skin is often used for tasks like welding where heat and flame resistance are the main hazards but dexterity is still important.
Extra layers of synthetic or natural fibers can be added to improve cold resistance. Molded TPR (thermoplastic rubber) material might be added to the back of gloves to offer impact protection for heavy duty environments such as oil rigs. The composition of the outer layers tailor the glove more specifically to the hazards of the task.
Finally, the gripping surface needs to have some additional properties while supporting the overall protection level of the gloves. The palm and fingers are often covered in a crinkle-textured, flexible coating such as latex or nitrile that can channel away moisture and allow for grip even when wet. These layers can even offer enhanced cut and abrasion resistance depending on the material.
Keep Workers’ Hands Safe with the Right PPE
If OSHA is right and most, if not all, of the 110,000 annual lost-tine hand injuries in the U.S. are due to workers not wearing hand protection or wearing the wrong protection, that means the number could be reduced to zero (or close to zero) just by providing workers with the right PPE.