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Nine Myths About Disposable Safety Gloves
Disposable nitrile, natural latex, and vinyl gloves, often referred to as thin-mil gloves, are used in a variety of distinct applications. Understanding the truths about glove performance is important in selecting the right glove for each application.
Myth #1: More Texture Means Better Grip
One of the most common misconceptions about disposable gloves is that more texture results in better grip. In fact, texture has very little effect on grip. It is possible to make an extremely textured glove with low grip and a smooth-surfaced glove with high grip.
Surface treatment is the most significant factor in the grip level of a glove. Natural latex is inherently sticky, or tacky, much like glue. Without proper processing, natural latex sticks together like a large ball of adhesive. To reduce this tack, the surface must be treated. The most common surface treatments are surface chlorination and coating. Chlorination changes the surface properties and creates a hard, lower-tack shell around the glove. Coating technology adds a new, lower-tack layer to the glove.
Reality: Surface tack, or grip, can be controlled by the level of chlorination or the characteristics of the coating.
Myth #2: Gloves Remain Safe Throughout Use
Throughout use, gloves can develop holes due to degradation and wear. According to one study, after only 12 minutes of simulated clinical use, natural latex and vinyl glove defect rates increased to 9 percent and 35 percent, respectively. Without proper curing and cross-linking, nitrile can swell and develop holes or defects over time. Failure is commonly observed in the crotch between the thumb and forefinger.
In addition to formulation and process, use factors, such as average wear time and application, affect the inuse defect rate. Buyers should consider the potential defect rate increase and the risk imposed. They should ask their glove suppliers for supporting studies on in-use testing. Buyers and users can perform a representative test themselves by wearing a pair of new, tight-fitting gloves for the prescribed use time and then removing and filling the gloves with water to see whether a hole developed.
Reality: Gloves degrade during use.
Glove suppliers frequently claim glove composition of "100%" of the respective materials. Without additives, it is practically impossible to produce a usable glove of any of these materials. Adding curatives, cross-link agents, and accelerators to nitrile and natural latex is essential to making a strong, durable glove. Vinyl requires plasticizers and activation agents. Surfactants, which help with film formulation, are another additive found in most gloves. Formulations typically require 4-10 percent of additives to make a good glove.
Reality: Claims of "100%" nitrile, natural latex, or vinyl are not accurate.
Myth #4: Fillers Always Diminish Glove Performance
Fillers are used broadly in gloves. Most manufacturers use or have the ability to use fillers to help reduce the cost of making a glove. Fillers are often difficult, but possible, to detect through advanced technologies such as Thermal Gravimetric Analysis.
Fillers help to reduce the cost of a glove and, up to certain amounts, actually can improve specific performance characteristics. For example, tear strength is significantly improved in natural latex gloves when a moderate amount of calcium carbonate is added. The key word is "moderate." Fillers up to about 15 percent are tolerable; anything above that can become detrimental to the performance and quality of the glove in use. Some manufacturers have experimented with up to 50 percent filler, with limited success.
Reality: When used in moderation, fillers can improve certain disposable glove performance characteristics.
Myth #5: All Allergy Issues Can Be Addressed by Using Nitrile or Vinyl Instead of Natural Latex
Glove-related allergies are a primary concern to many glove users. The belief that glove-related allergies are caused only by natural latex is a common one. Latex allergies are the most serious glove allergies because they can be systemic and cause anaphylactic shock. Latex allergies are also the most common type of glove allergies.
Some users confuse chemical allergies with latex allergies. There are often components in both nitrile and vinyl gloves that can elicit a chemical allergy. For example, nitrile gloves, like natural latex gloves, often use carbamates or thiazoles, which can cause a skin allergy. Certain vinyl gloves use activation agents that can also cause skin allergies. In all cases, the less a glove is washed, the more chemical residue is available for potential contact to the user. Users should consult their physician if they suspect an allergy to gloves.
Reality: Natural latex is not the only glove material that can cause allergies.
Myth #6: 'Powder-free' Means 'Clean'
Surface treatment is the most common way to remove powder from a glove. Two types of surface treatment are chlorination and the addition of a wax or polymer coating. Chlorination is the traditional process and requires gloves to be washed prior to packing. The washing process is designed to rid the gloves of residual chemicals.
Wax and polymer coatings allow a glove manufacturer to "strip and pack," avoiding the chlorination and washing process. Wax and polymer coatings can leave residual chemicals that have not been properly washed. Though not always harmful, the residual chemicals can contribute to skin sensitivity or process contamination.
Reality: The process of making a glove "powder-free" can leave residual chemicals on the glove.
Myth #7: Chemical Resistance of Powder-free Natural Latex is Similar from Glove to Glove
As discussed in myth #6, powder is removed from gloves by chlorination or coating treatment. The treatment type, or lack thereof, can affect the chemical resistance properties of the glove. For example, natural latex gloves achieve better overall chemical resistance when chlorinated. Chlorination changes the surface properties and creates a hard shell around the glove. This "plasticized" shell has proper ties slightly different from natural rubber and provides additional chemical resistance that would otherwise not be available. On the downside, over-chlorination can damage gloves, making them brittle and unusable.
Reality: Latex gloves varies from glove to glove.
Myth #8: All Disposable Gloves are Basically the Same
Disposable gloves come in several different material types. The most common types are made from nitrile, natural latex, and vinyl. Each of these types is based on commodity raw materials with price fluctuations that depend on specific market factors. In general, nitrile is often considered premium to latex, which in turn is often considered premium to vinyl. The fact is that materials are not equal in performance in all applications. Nitrile has better puncture resistance of the three and resists more chemicals overall, including oils and solvents. Latex has better tear resistance, often fits better, and provides better dexterity. Vinyl has the best electrostatic dissipation properties and resists sulfuric acid better than nitrile or latex.
Even within the same material, there are significant differences from manufacturer to manufacturer. Other factors influencing glove performance are raw materials, formulation, process, and washing. These vary significantly from glove to glove and can result in performance differences in most applications. Typically, standards for the different materials also are not harmonized. ASTM exam glove standards have different tensile strength requirements for latex, nitrile, and vinyl. Vinyl has the most relaxed strength requirement, followed by nitrile, while latex has the highest tensile strength requirement of the three.
Reality: Multiple factors affect the performance of a disposable glove.
Myth #9: Lower Priced Gloves Always Result in Cost Savings
One of the biggest mistakes made by disposable glove buyers is buying based solely on price. The overall value of a glove is much more complicated than just the price of a box. In addition to price, buyers should consider durability in the application, safety risks, and productivity.
Many gloves are not properly formulated or processed. They are often under-cured and do not last long in application. Medical exam applications consume the majority of the disposable gloves produced globally and nurses, the largest users, typically wear a single pair of gloves for only a few minutes before discarding and replacing for each patient. On the other hand, many industrial applications require 2-4 hours of continuous use of a single pair of gloves. This extended length of time stresses the glove longer and can lead to failures in a glove that would not normally happen during a short, routine medical exam. For longer use times, it is important to choose a glove that is properly formulated and processed to withstand the application. A 10 percent savings can quickly be negated by a glove that lasts only half the time.
Productivity is another very important factor when considering the savings of one glove over another. Often, workers will be more productive with gloves that fit well, have good grip, and lower hand stress. In addition, beware of lower-quality gloves that fail, causing injury and the resulting cost associated with workplace accidents. Productivity and prevention are important factors when considering the economics of glove use.
Reality: Many factors determine the "value" of a disposable glove.
Conclusion
Choosing the right glove type or source is not as simple as reviewing a specification or buying at the lowest price. A number of critical factors should be considered. Understanding the truths about glove performance is important in selecting the right glove for each application.
This article originally appeared in the April 2010 issue of Occupational Health & Safety.