Clear View: Tips for Selecting Effective Anti-Fog Safety Lenses
Safety managers generally are well-informed when it comes to safety eyewear guidelines and requirements. From spectacles and goggles to sealed eyewear, these primary forms of eye protection keep debris, chemicals, harmful vapors and damaging rays away from workers' eyes to support safety on the job and promote long-term vision health.
There also is general awareness that lenses for such eyewear come in a wide variety of tints, many of which can be selected based on user preference, while others are specialized for particular applications or light hazards. Less awareness exists, however, when it comes to anti-fog lens coating technologies. Yet, fogging is the single most common challenge faced by safety eyewear users today.
Not all lenses are coated to deter fogging and scratching, and not all coated lenses deliver the same level of protection from these effects. Effective anti-fog and anti-scratch coatings significantly can improve worker safety and productivity as well as lens longevity. These advantages combine to deliver big benefits to an employer's bottom line. This article takes a closer look at anti-fog lens coatings and offers tips for selecting those that deliver the greatest safety and cost benefits to employers.
Factors that Cause Fogging
Lenses become foggy for a number of reasons, all of which are related to temperature and humidity. The most obvious reason is a hot and/or humid work environment. Whether workers are outdoors in sticky summer conditions, or inside a steam-filled boiler room or food manufacturing plant, moisture in the air causes tiny droplets of water to collect on lenses, primarily on the outside surface.
Lenses also fog when workers exert themselves. As an individual's body temperature rises from exertion, the heat and sweat produced on his or her head and face cause lenses to fog, primarily on the inside surface.
Fogging also occurs because of the transitions between warm and cool environments, such as when workers move between a refrigerated storage unit and a hot loading dock, or from wintry outdoor conditions into a heated vehicle. When the temperature of the lens is cooler than the air, moisture will condense on the lens surface, causing the "white haze" that interrupts vision until the lens temperature rises and discourages further condensation.
A lesser-known factor behind fogging is daily washing. Each time lenses are cleaned with soap and water they are exposed to moisture, the very element they are designed to manage. Over time, the lenses' anti-fog properties are eroded, making them less capable of managing water from the environment.
Foggy Lenses Affect Safety, Productivity
Based on the wide variety of factors that contribute to fogging, it is easy to see how many conditions affect nearly every worker, in nearly every environment. No matter which factor causes fogging at your site, the effects of obscured vision among workplace hazards potentially can be catastrophic. It only takes a second for an accident to occur – a misstep, slip or fall; contact with machinery; getting struck by equipment; or coming into contact with chemicals or electrical current. The effect on the individual can cause life-threatening harm, even death, and the disruption and financial impact on the employer also can be devastating.
To combat foggy lenses, workers must remove their safety eyewear to wipe the lenses clear of moisture. When workers remove safety eyewear at the job site, they leave themselves vulnerable to potentially catastrophic injury as they expose their eyes to on-the-job hazards. If they choose to leave the workspace to wipe lenses clear, productivity takes a direct hit. Whether they remain in the hazard zone or exit it first, workers must stop work to wipe their lenses clear – sometimes frequently – which undermines productivity.
Anti-Fog Coatings Vary
The best defense against fogging lenses and the dangers caused by moisture-obscured vision is a high-performance, anti-fog coating. Today, anti-fog coatings commonly are manufactured with properties that manipulate moisture. High-performance coatings initially absorb moisture and then cause excess condensation to spread in a clear film over the lens surface. Highly controlled application methods deliver coatings that are very effective at spreading greater amounts of moisture, thus delivering a clear, fog-free view for a longer period of time.
The methods used for applying anti-fog coating to safety lenses vary widely, and applying it so it goes on and stays on – even after repeated washings and wiping – is key to the coating's durability and performance. Manufacturers of high-performance, anti-fog coating employ specially formulated coatings for longer lasting protection; apply a controlled layer of coating to absorb more moisture; utilize an intense curing process for greater coating longevity; and apply the coating in a clean, controlled environment so as not to disrupt lens optics.
Since eyewear manufacturers are not required to disclose their unique processes for applying coatings, seek trusted suppliers with a long history of delivering high-quality coatings, as some coatings easily are washed off and thus offer only limited usage before losing their properties.
A Versatile Solution
Anti-fog coating is versatile, and can be applied to safety eyewear styles used across industries and applications. When applied to eyewear in various lens tints, it improves visibility and safety for workers in virtually any lighting application. When used on face shield visors, which are a secondary form of eye protection, it prolongs fog-free vision in environments with combined eye and face hazards. In extreme environments where airborne debris and particulate matter are widespread, look for lens options that feature both anti-fog and anti-scratch coating technologies to promote a clear, fog-free view and to prolong the life of the lens.
In the case of safety goggles and sealed eyewear, selecting an effective anti-fog coating is important. Because these types of eyewear are designed to form a tight seal to the face, less air circulates to help move moisture and heat away from the eyes. Body heat alone often is enough to fog the inside lens in goggles and sealed eyewear. Add exertion and perspiration and your workers' vision is sure to be blurred in short order unless high-performance, anti-fog coating is applied.
Anti-fog coating also is an important consideration for prescription safety eyewear. Outfitting workers with Rx eyewear is more important than ever to protect the estimated 70 percent of workers who require vision correction in today's workforce. The number of Baby Boomers comprises an increasing percentage of the workforce, so be sure that anti-fog coating is part of your Rx safety eyewear selection. Ensuring a clear view for this vast and growing majority of workers will support a healthy and productive workforce for years to come.
Fogging is the No. 1 challenge faced by safety eyewear users, and eyewear manufacturers continually seek new and improved technologies for delivering long-lasting, anti-fog protection. By understanding the benefits that anti-fog coatings deliver and by seeking out the latest high-performance solutions, employers support not only productivity and the bottom line, but also the organization's shared vision for a successful culture of safety.
Phil Johnson is director of technology, Eye & Face Protection Group, Honeywell.