First comes the Fog, then comes De-Fog
What do you think is the most common problem you can run into on a rainy day? If you use a car, visor, goggles, helmet or other plastic/glass materials often, then you probably know the answer; Fogging! Fogging occurs when atmospheric humidity close to a transparent surface condenses. This is as a result of the difference in the temperature of the surface and the surrounding air. As the surface tries to balance between the two temperatures, heat energy is released. The water molecules become gas and the energy within it decreases to form small water droplets on the surface. These water droplets are referred to as fog. To clear this up, anti-fog coating is used.
Luckily, water molecules are attracted to glass, and if this attraction should be enhanced, the surface tension which draws its molecules together to form droplets can be overcome. The mechanism of anti-fog technology depends on this concept to overcome the surface tension so that the water spreads out in sheets.
The coating needs to be constantly exposed to UV light which is what charges them and as such, they do not function well in low light or in the dark. Most anti-fog coatings are temporary, as they only work for three months to a year before they stop working completely.
Fogging is annoying, especially for people who use recommended lenses. When the atmospheric moisture condenses and your glasses fog up, it leaves you virtually blind and this can be dangerous if you drive on a highway street in winter wearing your lenses. Tired of foggy eyewear? How do you keep your lenses from fogging up? Prepare for salvation in the anti-fog coating as you learn about various ways to de-fog all your transparent accessories.
Anti-fog coating, meaning?
Anti-fog or anti-fogging agents and treatment are chemicals that prevent fogging on the surface on which they are applied by inhibiting the condensation of water on the surface.
Origin, History, and Improvements in Anti-fog Technology
Anti-fog chemicals were actually developed by NASA during the Gemini program to be used on helmet visors. During one of their first space suit space-walk tests, an astronaut experienced fogging in his helmet visor. This prompted NASA to develop the anti-fog solution, and the anti-fog technology has continued to be improved upon and perfected till today.
There are many types of anti-fog chemicals, coating, and technology. New and improved versions are being developed as technology evolves. The most popular chemicals used as anti-fog are called surfactants and they act by minimizing the surface tension of the water.
Everyday Anti-fog: Myth busting
There are online myths about household materials that could serve as anti-fog agents. They are called demisters and some of them prevent fogging of transparent surfaces, but how effective are they? Let us demystify the myths of the demisters and help you figure out the truth.
A lot of people dip their goggles in the pool or apply fresh water to their glasses to prevent fogging, this does not work. Water is not an anti-fog agent.
Saliva to your lens? Well, this may keep it from fogging for a few minutes but it is ineffective for long, not to mention disgusting.
Treat your glasses with naked flame? No! Apart from the fact that this is false, it could also destroy your glasses or deteriorate the anti-fog properties that glass or lens probably has.
Toothpaste? This also works as an anti-fog agent but it is not advised on glasses with some form of anti-fog properties as it is abrasive and could potentially remove any existing anti-fog in your goggle. When applied to swim goggles, it smells, works well but it isn’t quite worth it when it comes to recommended lenses. Plus, getting all the toothpaste out is too much work. Detergents such as shampoo, soap, or shaving cream also act like toothpaste as an anti-fog agent.
The above screens, goggles or any other surface that would not leave you blind if things go awry. So, for your recommended lenses, you need real manufactured anti-fog coating or solution. Industrial anti-fog coatings are optical thin film coatings usually made from hydrophilic coatings that maximize surface energy: e.g. Polymers and hydrogels and they prevent fogging at very low or high temperatures. With anti-fog coating, glass remains clear 100% of the time, no condensation build up on the outside of the case. It is sustainable and environmentally friendly.
Applications of anti-fog coating
Long lasting anti-fog coating has lots of applications. They are available in different varying types and for different functions. An application can be on high-reflectivity mirrors to reduce glare or improve transmission, siloxane coatings for improving durability and abrasion resistance, specialty UV-cured coatings for military and safety lens applications, super-hardcoats for extended wear and increased hardness and many more. They also serve beam splitting, dichroic, dielectric, gold infrared, metallic, transparent conductive, ultraviolet, optical, narrow bandpass uses.
Anti-fog coating is typically applied on goggles, dive masks, car windows, visors, kitchen backsplash and bathroom back-painted glasses, hard surfaces, and other surfaces. Most anti-fog coating materials are temporary or at least wear off after a period of time. Although these temporary anti-fog coating techniques and chemicals are still used today, there has been a significant evolution in anti-fogging chemicals which has produced a permanent anti-fog coating that lasts for life.
In July 2012, researchers with the Université Laval in Quebec stated in their patent that the process of producing permanent anti-fog coating consisted of: “A first polymer layer resulting from covalently bonding a polyanhydride polymer to said surface; and a second polymer layer resulting from covalently bonding a polymer of polyvinyl alcohol, partially hydrolyzed polyester, polyether and cellulose derivative.”
Removing your eye wears to wipe away fog can be potentially dangerous as it would leave your eyes vulnerable to dangerous substances like dust. This could be detrimental to the eyesight, especially to those who have one eye defect or another. This is why permanent anti-fog coating is advised by health professionals. This way, you won’t have to clean your lenses or visors when you run into a cold or rainy day.
After years of its invention and constant evolution at Advanced Nanotechnologies, we’ve finally found a more permanent solution for anti-fog coating, still, research always continues today to develop anti-fog and anti-frost coating in a bid to make glasses remain fog-free in any temperature.