When glass fogs, whether clouding the inside of a car windshield or steaming over eyeglasses at a stove, it is annoying and hazardous. Car fogging reduces vision and blocks out approaching vehicles or pedestrians. Home fogging of a bathroom mirror cuts visibility for shaving and other tasks. Natural anti-fog solutions are as close as your bathroom cabinet or kitchen sink.
Glass fogs because of condensation. Water is always in the air, even if the water molecules are too small to be seen. When the water vapor reaches a cold surface such as glass or a mirror, the vapor condenses and turns into liquid droplets on the glass. These droplets form the fog that interferes with light reaching the eye. Bathroom mirrors and shower doors fog more readily due to excess moisture and warm air in the room that settles on cool glass surfaces.
Use air movement to reduce fogging naturally. Install and use exhaust fans to anti-fog home glass. These fans pull out the excess moisture in the bathroom or kitchen, removing the water vapor that fogs the glass. In automobiles, vent fans on the windshield create a flow of air that dispels the water vapor and equalizes the glass and air temperature so that condensation does not occur. Although commercial chemicals coat glass with films that block water vapor from reaching the glass, these chemicals are sometimes challenging because they require buffing or time-consuming application. They wear off after time and require repeat applications. These chemicals have odors objectionable to sensitive people.
Household products, applied to clean glass, keep fog from forming or reduce condensation. One method uses vinegar. Use a half-cup vinegar or sudsy ammonia in one gallon of water. Apply to windows, mirrors or shower doors. Dry with a lint-free cloth. Another home recipe mixes one-half cup sudsy ammonia, two cups rubbing alcohol, one teaspoon of liquid dishwashing detergent into a gallon of water. Spray this solution on glass and wipe it dry. In the bathroom, try a spritz of shaving cream on the mirror. Wipe it dry before showering or turning on hot water. Or put a dab of regular toothpaste, not gel paste, on the mirror. Wipe it on, rinse and dry. Dab a few drops of liquid dish detergent on a cloth, wipe it on, rinse and dry. The soap leaves a light film that blocks water vapor from the cold glass.
Anticipate potential fogging and use anti-fog remedies before you need them. Exhaust fans or car defog fans are most effective when they are turned on before the excess water vapor hits the cold glass. Apply anti-fog solutions before fogging occurs. Keep a dry cotton cloth handy for quick defogging because natural cotton absorbs water droplets better than polyester or other synthetic fabrics.