Anyone who has had the pleasure of wearing a pair of glasses at the very moment an extreme temperature change takes place has experienced fogging. It can happen when you are climbing out of an air-conditioned car into hot and humid air. It can happen during the winter, when you're stepping from a toasty warm cabin into a winter wonderland. One way or the other, the effect is the same: you are blinded by the moisture.

Fog doesn't discriminate. It doesn't pick on cheap drugstore sunglasses or prescription eyewear while leaving everything else alone. Fogging up is a problem with designer sunglasses and discount bulk sunglasses alike. So what causes it? Better yet, what can we do about it?

Condensation Is the Culprit

Glasses fogging up is all about condensation. When a warm, moist surface comes in contact with cooler, dryer air, water droplets form. It is really no different than what happens to the mirror when a person showers in the morning. The degree to which it happens is related directly to temperature differences.

The more drastic the difference, the more likely condensation is to occur. So imagine you are on the beach during the heat of the summer. Right off the beach is an air-conditioned cafe selling cold drinks and snacks. Your sunglasses could fog up the minute you step inside. Or it can happen the other way around. You could be inside for a length of time, then step outside and get blinded by the moisture.

Obviously, humidity also plays a role. You need at least some humidity to create condensation. This is why the previous example of stepping out of an air-conditioned car into hot, humid air works. The humidity outside the car is what produces the blinding fog.

What Consumers Can Do About It

All of this begs the question of what consumers can do about sunglasses that fog up. One possible suggestion is to adjust how they are worn. Wearing sunglasses slightly lower on the nose can improve air circulation. This can reduce heat and moisture buildup between the lenses and the face.

In cold weather, wearing a mask or scarf in such a way as to direct your breath downward will keep moist air away from the lenses. Here are some additional tips:

• Anti-Fog Sprays – Some people use anti-fog sprays and wipes. The products contain a harmless chemical that leaves a thin but protective film behind. That film reduces fog by lowering the surface tension of any water that comes into contact with the lenses.
• DIY Solutions – It is possible to enjoy the same effect one would get from a commercial anti-fog product by using things most people have around the house. For instance, rubbing shaving cream into a pair of clean lenses, then wiping with the microfiber cloth, works very well.
• Gradual Temp Changes – Another helpful tip is to make temperature changes more gradual. This doesn't generally help people with prescription eyewear, but it is a good tip for designer sunglasses. For example, throwing a pair of sunglasses in the refrigerator for a minute before stepping out into the cold can eliminate fogging entirely.
• Regular Cleaning – Regular cleaning can help illuminate the dirt and smudges that normally attract moisture. The cleaner the lenses are, the more difficult for moisture to hang on.

Whether it is wholesale designer sunglasses from Olympic Eyewear, or the cheapest pair of gas station sunglasses one can find, they all fog up from time to time. The combination of moisture and temperature change sees to that. Proper care can reduce fogging, but eliminating it completely is almost impossible.