Why are your car headlights fogging up? Simple solution, no more fogging
The principle of fog formation

The principle of fogging is that after the local humidity reaches the saturated vapor pressure, water vapor encounters dust and forms a water film on the surface that is not smooth enough. The water film forms small water droplets under the action of surface tension. The small water droplets react under the surface tension and Under the action of gravity, they merge with each other to form large water droplets visible to the naked eye. This is the fog that everyone usually sees.
Water vapor diffuses into the lamp through the ventilation device of the car lamp. This is inevitable. The lamp is not completely clean. Of course, the inner surface of the lamp mask is not completely smooth, so when there is enough water vapor, it will naturally fog up. , this is also impossible to avoid in principle.
Speaking of which, I guess you are still confused. This still misses the point. Why do my car lights not fog up when I turn them on, but fog up when I turn them on?
In principle, once the car lights are turned on, the temperature inside the car lights will definitely rise. When the temperature is high, the saturated vapor pressure is also high, which means that the required amount of water vapor needs to be higher, which makes fogging impossible...
In layman's terms, the amount of water vapor in the air inside the car lights is certain. If it cannot fog the low-temperature car lights, it will definitely not fog the car lights after the temperature rises, because the higher the temperature, the more likely it will fog. Fog requires a greater amount of water vapor.
But the fact is just the opposite. The fact is that when the car lights are turned on, it will fog up. Why is this?

The culprit of fogging
After checking various literature, looking for various information, and doing various experiments, I finally found the reason. This reason makes me heartbroken. I shed tears every time I talk about it. The days and nights I spent doing experiments...
The reason is that most of the car light parts are made of plastic materials, polymers, etc. Materials like this are porous in microscopic dimensions. The porosities lead to strong capillary action, and the capillary action makes it easy to absorb water, so the lights are not turned on. When the temperature is low, it will not volatilize water vapor to the outside. When the light is turned on and the temperature rises, it will volatilize water vapor into the lamp. In this way, the amount of water vapor in the lamp will increase. In some parts, the temperature is low and the water vapor reaches the saturated vapor pressure, forming water vapor!
The first thing to explain is that the headlights are sealed, but not vacuum. The headlights will generate a lot of heat during use, whether you are using halogen lights, xenon lights or LED lights, so from the perspective of heat dissipation It is said that a ventilation hole will be left for the headlight to remove excess heat and keep the entire headlight in a stable environment. Water vapor exists in the air. The headlights suck the water vapor in the air into the lampshade through the ventilation holes. The water vapor is adsorbed on the surface of the lampshade. This is what we often call fogging.
Of course, don’t panic when the headlights fog up under normal circumstances. At this time, the ventilation holes that we think are the culprits will come out to rescue. After the headlights are turned on, the temperature rises, and the water vapor can be eliminated through the ventilation holes. Don't take measures when you see water vapor in the headlights, such as using baking equipment to bake. Otherwise, don't cry when you regret it.

The more common reasons for water in the headlights include:
1. Seasonal reasons
In autumn and winter, when the temperature changes too much, it is easier for the headlights to fog up. This is the situation we just mentioned.

2. Water flush engine
When the engine is running, it will generate a lot of heat. If you flush the engine with water at this time, we will see a large cloud of mist. The water and heat will conflict, and the water vapor will penetrate everywhere. It is very likely that it will enter the inside of the headlight from the exhaust hole.

3. Sealing issues
It is often found that water has entered the headlights after it rains or after washing the car. At this time, you need to pay attention. The exhaust holes of the headlights are usually inside. It is difficult for car wash water and rainwater to enter the headlights through the exhaust holes, so it is often found under the rain. If the headlights fog up after rain or washing the car, it is likely that there is a problem with the headlight seal. The reasons for the headlight sealing problem are: 1. The sealing rubber strip on the back cover of the lamp shade has aged and its elasticity has decreased, resulting in loose sealing; 2. The lamp shade or the joints of the lamp shade are cracked and damaged.
If you encounter the first and second situations, it's okay to say that they can be eliminated as long as the headlights are turned on for a while. But if you encounter the third situation, you need to repair the headlights. During the warranty period, you only need to turn on the headlights for a while. Fourth son shop, just ask them to repair it for you. After the warranty period, it is just a simple crack in the seam of the lampshade. Generally, the car light modification shop will provide such repair services. But if the headlight lampshade is cracked, there is no choice but to replace it. However, you only need to replace the lampshade. That’s it, you don’t need to replace the entire headlight assembly, which is much less expensive.
If the headlight is flooded, you need a pair of high-quality bulbs. Water in the headlight can easily cause a short circuit in the circuit, affecting driving safety. Therefore, I recommend Haili VIN77 to you. It is stable, bright, quick to start, and environmentally friendly. Haili will protect your safety.
