Principle
Bathroom mirror has a tendency to get misty or foggy when there is a bath or shower or using water in the sink. During a shower, the air gets warmer due to warm water vapour suspended in the air. The air suspends tiny water droplets until the air is saturated and the droplets fall to the floor. When water droplets come into contact with cooler surfaces such as mirror, glass or tile, they are cooled and condensed back to liquid form, creating a film of water on the cooler surfaces. If the shower room gets steamy enough provided the mirror is cool enough, mist or fog is formed on mirror. If water vapour gets more and more and/or mirror is much cooler than water vapour, condensed water may run down mirror surface looking like streams. One of the most efficient solution to get rid of condensation water and to prevents it from further forming is to warm up the mirror until it is about 10℃ to 15℃ higher than air temperature.
Demist film is used to warm up the mirror. There are electric wire embedded in between two layers of well protected and electric insulated plastic film. When voltage is applied, electric current passes through the electric wire. Thus, protective plastic layer is warmed up by means of heat conduction. The protective layer is adhere on mirror back. The heat of protective layer is then conducted to mirror back and warm up the mirror eventually. When mirror temperature is higher than environment temperature, moisture or on mirror surface is eliminated and consequently, demist and prevents mist from further condensation on mirror.
