Fog can form on the surface of the eye glasses when the water vapor in the air condenses. This can happen if the temperature of the lens is much lower than the surrounding air. This is especially noticeable when a person is coming in from the cold into a warm room.
The fog that builds up is actually not a continuous film, but rather, a bunch of tiny water droplets that bands itself to the surface of the person’s eye glasses. As a result, the light that passes through is reduced and not transmitted properly.
Optifog Lens and Activator by Essilor
Optifog Activator is a solution that can be dropped into a person’s eye glasses to help keep the Optifog lens free of fog. It works by spreading the water droplets causing the fog to distribute evenly across the surface of the lens, thereby rendering them invisible.
The Optifog lenses are available in a variety of lens materials, namely plastic, polycarbonate or in high index plastic. It has an anti-fogging property that is activated by putting a drop of the Optifog Activator solution on each side of the lens and wiping it with a microfiber cloth.
The solution must be applied once a week, as the treatment is only designed to keep the lens free of fog for 7 days.
Fog Free from Opticote
A more permanent solution is the product created by Opticote, an eye glass lens coating company. Their solution, called Fog Free, can be applied to any lens made out of plastic, polycarbonate, high index plastic and even the photochromic lenses made by Transitions.
Fog Free, however, must be applied before the lenses are even cut to fit your frame. The advantage of this is that it totally and permanently eliminates the condensation of moisture that causes the fogging of your lenses.
Another permanent coating that can be applied to a person’s eye glasses is polyvinyl alcohol. A team headed by Gaetan Laroche of the Universite Laval developed this solution.
Polyvinyl alcohol is touted to permanently remove the fog in all lens surfaces, be it for spectacles, vehicle windshields, camera lens and practically any other transparent surface made out of glass or plastic. The solution adheres to the base of the surface after the application of four layers of molecules. Each forms a strong bond with its respective adjoining layers.
The end product is a multilayered coating that is so thin and transparent that it does not change in any way the optical characteristics of the surface. It can also withstand washing, thus eliminating the need for repeated application.