Every week dozens of hand protection distributors, safety officers and end users turn to the manufacturing community for answers to their questions about chemical-resistant personal protection equipment (PPE) for workers’ hands. Many of the questions come up time and time again. Here we have addressed those that are asked most often.*
Sulfuric acid is the top produced inorganic acid in the U.S. Used in batteries, agricultural applications, ore processing, refining and many different applications, it is one of the most often stored and spilled chemicals in the U.S. and worldwide. As with all acids, the concentration of the acid can make a big difference in finding the best glove material:
On the cold side, it is very difficult to find proper hand protection from cryogenic materials. Most of the elastomeric glove materials associated with chemical resistance do not hold up in cryogenic applications where there is direct contact with liquid nitrogen or anhydrous ammonia. These materials may shatter like broken glass. Neoprene, for example, hardens due to its inherent crystallinity at temperatures that are not even as cold as the cryogenic realm. Some PVC gloves are specially formulated to remain soft at low temperatures. In high temperatures, extreme caution is advised if you are using a chemical such as an acid or caustic.
Permeation breakthrough times are based on testing at ambient temperatures. Raising room temperatures causes breakthrough to occur in a much shorter amount of time. Hot acid or caustic can have catastrophic consequences when coming in contact with the skin, producing extreme damage. Even though there are gloves such as insulated Neoprene gloves that are generally very good against most acids, if the acid is heated, it becomes a much more dangerous situation. Contact with hot acid should be avoided if at all possible.
A widely used laboratory and industrial chemical, acetone is ideal as a cleaning solvent in laboratories because it is soluble in water, polar and excellent at removing residual chemicals from glassware. In addition, it evaporates quickly. It is also used to remove nail polish and acrylic nails and superglue.
There is no real evidence that acetone is acutely toxic, and it has not been shown to produce any teratogenic, carcinogenic or mutagenic activity in humans or animals and is generally recognized as safe. However, it can cause dryness and de-fatting of the skin on the hands, which can lead to irritation. Also, acetone causes a stinging experience on any area where the skin is broken.
While everyone wants an inexpensive, disposable glove to use with acetone, there is no disposable glove that offers protection from it or any other chemical in the ketone class. The choices for heavy exposure are limited to non-disposable gloves and each glove choice that works has weaknesses:
You should consult a chemical database or call an expert for suggestions on what to wear when you are exposed to a mixture. Many mixtures contain a variety of chemicals from different classes, including both polar and non-polar solvents as well as aliphatic and aromatic hydrocarbons. For example, most strippers or thinners are made intentionally with many different chemical classes such as ketones, alcohols and aromatic and aliphatic hydrocarbons. These cut through almost any paint and, unfortunately, most glove materials. Always check the Material Safety Data Sheet (MSDS) for the mixture, and look at the main ingredients as well as the relative proportion of the constituents. This is difficult. Most of the time, one or two ingredients will determine which glove will work best. On the down side, the information on the MSDS may be somewhat vague, and many times the only gloves that will prove satisfactory are also quite expensive. Most often laminate film gloves are the only gloves that will work for mixtures of chemicals that represent more than one class of organic chemicals.
Many times a chemical has not been tested. With so many chemicals being developed every year, not all chemicals have been tested for permeation. This can be because the analytical test method for permeation is not amenable to the chemical nature of the compound, such as a compound with very low vapor pressure. Many questions have been asked about compounds that are crystalline. For the vast majority of crystalline chemicals, natural, Neoprene, nitrile or PVC gloves provide excellent protection. Only organic chemicals that sublimate or go from the crystalline state to a gaseous state may permeate.
You simply cannot wear the same glove for transporting drums that you wear for pipetting micro-liter quantities of a chemical into a volumetric flask or injecting a sample into an HPLC or GC/MS for analysis. Many times, wearing a thick, chemical-resistant glove designed for safe immersion in a test chemical could cause more hazards, from spilling a dangerous chemical or dropping the container. To address this issue, some websites have data published from permeation testing from the worst-case scenario - simulating total immersion in a test chemical for 8 hours - to data for intermittent contact or splash contact. Thinner gloves that offer the maximum in dexterity and touch sensitivity are safer choices for laboratories and applications that require a more exacting touch. The trade-off is less protection from the chemical. Most of the time, the wearer should seek the most appropriate polymer choice and layer the gloves, changing gloves as soon as feasible after the gloves come into known contact with a chemical.
Providing effective hand protection from chemicals is always a priority in the workplace. Whenever a new chemical is introduced to the workplace or temperature conditions change, it is important to re-evaluate the PPE being used. If the answer to your need is not clear, don’t hesitate to ask the experts at the glove manufacturing laboratories. We’re there to evaluate your situation and to give you the best solution possible.
*Author’s Note: With the global workplace containing thousands of chemicals that are potentially hazardous to the hands, chemical-resistant glove choices are very specific. Resources such as the chemical resistant glove guide at www.chemrest.com can help workers find the proper protection.