Antifog. Dealing with foggy windows
Why do car windows fog up?
Glass fogging is a pure physical process. There is usually some water vapor in the air. The physical quantity that is used to describe the amount of water in the atmosphere is the humidity of the air. It is measured in percent or grams per unit mass or volume. Usually, to describe the moisture in the air in everyday life, they use the concept of relative humidity, which is measured as a percentage.
After the air has saturated 100% of the water, excess moisture that comes from outside will begin to condense on the surrounding surfaces. There comes the so-called dew point. If we consider a car, then the temperature difference in the cabin and outside of the car contributes to the condensation process: moisture settles faster on colder glass than on other surfaces in the car.
How does anti-fog work?
All modern antifogs are made on the basis of alcohols, usually simple ethyl and more complex glycerin. To increase the effectiveness, surfactants are added to them. To increase the duration - composite polymers. To mask the alcohol smell, many manufacturers also add fragrances to their products.
The essence of the work of the anti-fog is simple. After application, a thin film is formed on the glass surface. This film, contrary to the misconception, is not a purely hydrophobic coating. The property of repelling water is inherent in another category of auto chemicals: anti-rain products.
The film formed by anti-fogs only reduces the surface tension of the water that falls on the treated surface. After all, visibility through misted glass drops precisely because moisture condenses in the form of small drops. Water itself is a clear liquid. Drops have the effect of lenses. Microclines made of water of different sizes and shapes chaotically scatter the light coming from outside, which creates the effect of fogging the glass.
In addition, the formation of water into droplets impairs its evaporation from the glass surface. And if moisture settles in a thin homogeneous layer, it is easier to be carried away by circulating air currents and does not have time to form a matte coating.
A brief overview of defoggers
Today, there are quite a few different car glass products on the market that promise to prevent condensation from forming. Let's consider them.
- Verylube antitumor. Manufactured by a division of Hado. Available in 320 ml aerosol cans. Apply directly to glass. After application, excess product must be removed with a napkin. Does not form a layer visible to the eye. Judging by the reviews of motorists, it works efficiently and prevents the formation of condensation on the windows for at least a day. Works well even in very wet weather.
- Shell Anti Tooth. Means from a higher price segment. Sold in 130 ml bottles. The method of application is standard: spray on the glass, wipe the excess with a napkin. According to drivers, Shell anti-fog lasts a little longer than cheaper products.
- Hi-Gear Anti-Fog. Quite a popular tool among Russian motorists. Available in 150 ml plastic bottles. In comparative tests, it shows results above average.
- Anti-fogger 3ton TN-707 Anti Fog. Inexpensive tool. Produced in a 550 ml bottle with mechanical spray. The effectiveness and duration of the effect is average.
- Soft99 Anti-Fog Spray. Aerosol antifog. It differs from other representatives of this segment of auto chemical goods by an additional anti-reflective effect, which affects the relatively high cost. After application, the glass must be wiped with a soft cloth. Leaves a barely noticeable oily layer. Motorists positively note the property of Soft99 Anti Fog Spray to resist fog, however, according to them, the anti-glare effect is weak.
Also, to combat glass fogging, there are impregnated wipes on sale in the Russian markets. One of the well-known manufacturers is Nanox. Active ingredients do not differ from liquid products. The only benefit is faster processing.
