How Do Anti Fog Coatings Work? & Are They Effective?

None of us are strangers to our glasses fogging and creating an impossible haze through which it’s nearly impossible to see. Whether you experience fogging on your sunglasses, eyeglasses, or safety glasses, it becomes an irritating event that can also place your eyes at risk of injury. 

Anti-fog solutions are plentiful, but the true Cadillac of anti-fog fixes is an anti-fog coating applied during the eyewear manufacturing process. All Stoggles safety glasses come standard with this semi-permanent, anti-fog coating. 

Let’s nerd out and talk about why your glasses fog in the first place and how this magical lens coating prevents it from happening. 

Fog Formation Information

Do your glasses fog when you wear other PPE like a face mask, when you walk outside from indoors, or vice-versa? The reason is because of the temperature difference and the level of moisture in the air. 

Let's discuss how you get foggy glasses.

Warm, moist air that hits a cool surface causes fogging. Thus, when your hot breath escapes your PPE face covering and hits the surface of your glasses’ cooler lenses, they fog.

Likewise, when you leave the cool comfort of your home and step out into the blazing heat of summer, your glasses also fog. The fogging continues until the surface temperature of your glasses matches the surface temperature of the air (or warm breath) that surrounds them.

You could add a flexible metal strip to seal the mask to your cheeks and nose. You could strap it down with adhesive bandages or athletic tapes (but those aren't fun to rip off. At. All). 

It's important that your mask fits well, but there are some extra ways to ditch the fog.

Adhesion and Cohesion

If you’re wondering why the little water droplets attach themselves to the surface of the lens in the first place, it’s because of two specific properties of water: adhesion and cohesion

  • Adhesion. Adhesion causes water to stick to surfaces like glass. It’s the reason why you’ll see water droplets clinging to the branches of plants.
  • Cohesion. At the same time that adhesion is working to help water stick to other surfaces, cohesion is helping water stick to itself. Water’s cohesive properties cause it to stick together, bead up, and create surface tension. 

An example of water’s cohesion and adhesion in action can be seen in a glass that is filled with water just past the top. The water appears slightly higher than the top of the glass, but it doesn’t spill over. Both properties help water stick together and stick to the edges of the glass. 

On your glasses, adhesion and cohesion cause tiny water droplets to form and stick to your glasses, which creates fog. 

Here are our recommendations for keeping your glasses fog-free:

Anti-Fog Solutions

The most popular solution for dealing with glasses that fog is taking them off and wiping them on your shirt. Your glasses fog, then you immediately remove them, grab the bottom of your shirt, and wipe. 

There are four problems with this solution.

  1. It could harm your glasses. Your shirt probably isn’t incredibly clean. If there are dust particles on it that could scratch your glasses, you could end up with lenses that are not just foggy; they’re damaged. 
  2. It takes you off task. If you have to stop to clean and wipe off that thin film of fog, you’re going to have to stop what you’re doing. Whether it’s work, a game, or a home improvement project, removing your glasses to clean them is an automatic time out. 
  3. It’s dangerous. If you’re wearing safety glasses, removing them to clean the fog from them could place your eyes at risk of injury. Eyes that are left vulnerable even for a few minutes could result in an eye-related injury that could impact your vision and/or cause time off from work. 
  4. It’s not permanent. The minute you place your glasses back on your head, they’ll likely fog again, which means you’ll end up having to wipe your glasses again.

The next go-to solution is usually anti-fog wipes. But although they prevent fogging for a little while longer than wiping with your shirt, they still cause the same issues that the shirttail method does; removing your glasses, taking you off task, and risking eye injury.

Anti-fog wipes are a step in the right direction because they make use of anti-fogging chemical agents.

Let’s look at how these work and how they are integrated into anti-fog lenses. 

Anti-Fog Coatings

Anti-fog coatings were developed by NASA during Project Gemini in 1966. During a spacewalk, a NASA astronaut’s face shield continually fogged. This made it impossible for him to see. The helmet shield was later coated with a specific chemical that fixed the problem, and the anti-fog coating was born. And every glasses-wearer everywhere rejoiced. 

There are two types of anti-fog protective coatings: hydrophilic coatings and surfactants. 

Surfactants

Surfactants are solutions that are applied to the surface of a lens to prevent fogging. Surfactants aren’t permanent, which means they won’t help your glasses remain fog-free permanently. Anti-fog wipes contain surfactants.

Common household solutions like dish soap and toothpaste also act as surfactants, although applying them to your eyeglasses isn’t recommended. Save the vinegar and baking soda for recipes and the shaving cream for the shower.

It's time for an upgrade.

Hydrophilic Compounds

Hydrophilic compounds work by creating a coating on a surface that attracts water. These are usually applied during the manufacturing process. They are either permanently sealed on top of the lens or integrated into the plastic. 

How They Work

Both types of anti-fog coatings (surfactants and hydrophilics) work by altering the degree of wetting that happens on your glasses.  Wetting refers to how water reacts when it hits a particular surface. 

Remember that water has both adhesive and cohesive properties. If you change the way water reacts to the surface of your glasses, you can alter these properties. Thus: 

  • Surfactants work by decreasing the surface tension (cohesiveness) of water. They make it harder for water to stick together, causing the water molecules to remain extremely small instead of beading together. Fog occurs, but it’s barely visible. 
  • Hydrophilics work by creating a very water-friendly, water-attractive (adhesive) surface. Hydrophilic compounds act like a sponge, soaking in water and releasing it to the edges of your lenses. Fog occurs, but it’s quickly removed.

Most anti-fog coatings on glasses are hydrophilic. They are either permanently affixed to the surface of your glasses (similar to the way the tint is sealed to sunglasses) or integrated into the plastic. 

Is It Permanent?

No anti-fog treatment is completely permanent. It breaks down over time, even if it is integrated into a pair of high-quality lenses. Normally, anti-fog coating lasts about a year. After that time period, you won’t necessarily need to replace your glasses; you may just notice they begin to fog a little when you wear them. 

Are Stoggles Anti-Fog?

All Stoggles glasses are anti-fog. Our glasses are made from a super lightweight polycarbonate material and contain an anti-fog coating, so you never need to wipe them down or take them off. No matter if you’re working indoors, outdoors, or in a setting with additional PPE (like a mask), you’ll never have to worry about foggy lenses. 

Why Stoggles?

You could buy a pair of safety glasses from the big box home store, so why buy a pair of Stoggles instead? Glad you asked.

Here are just a few reasons our safety glasses are a better solution. 

  • Impact resistance. The ultimate in safety, our glasses are ANSI Z78.1+ certified, which means they are high mass and high velocity tested to resist breaking, shattering, or splintering if struck with an object. 
  • UV blocking. Whether you’re outside in the sun or catching UV rays from welding or soldering, our glasses have you covered. Our polycarbonate material is naturally UV-blocking to prevent damage to your eyes. 
  • Blue light blocking. Ever spend time in front of a blue-light emitting device (like a phone, tablet, computer, LED television, or under fluorescent lighting)?

If so, you’re exposed to blue light, which can travel through your cornea and lens directly to your retina. Our glasses are all coated with blue light blocking technology.

  • Serious style. If you’ve been wearing ill-fitting, bulky safety glasses (and feeling less than dapper), our glasses are the solution. Available in two different shapes, two different frame sizes, and numerous colors, our streamlined safety glasses are sleek, safe, and effortlessly sophisticated. 

There’s no wrong way to Stoggles. Our glasses are great for home, work, and play. In fact, you’ll likely find you wear them more than your regular glasses. Need prescription lenses? We do that, too. We handle all prescriptions in-house to save you time and money. 

Anti-Fog Technology But Make it Stylish

You need glasses that won’t fog and annoy you, but you also need glasses that are comfortable enough you’ll actually wear them.

Stoggles are the answer. Our glasses resist fogging while capturing your irresistible style, so you never have to choose between keeping your eyes safe and keeping your impeccably styled reputation ever again. 

Banish fog (and bad glasses). Stoggles give you the freedom to stay safe and stylish.


Sources:

How to Keep Your Glasses From Fogging Up While Wearing a Mask|Cleveland Clinic.org 

Anti-fog | National Aeronautics and Space Administration|NASA.Fandom.com 

Dancing Droplets - Scientific American 

Adhesion and Cohesion of Water | US Geological Survey 

Anti-Fog Compound | NASA Spinoff

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