Are Rearview Mirror Rain Guards Actually Useful?

[RyderLee]

Rain guards, as a traditional method of rain protection, do have certain effectiveness, especially during light rain. However, their performance is not ideal during heavy rain. Here is some information about maintaining visibility in rearview mirrors during rainy conditions: Using soap or detergent as a cleaning agent: Cleaning agents contain surfactants, whose hydrophobic groups physically drive water outward, preventing water droplet formation. The operation is quite simple: apply or spray soapy water or detergent solution onto the rearview mirror and let it dry. While this method is very convenient, its effectiveness is short-lived, typically lasting only about 2 days. Applying wax to rearview mirrors: When water comes into contact with a waxed surface, the internal cohesion of water becomes greater than its adhesion, preventing droplet formation - a principle similar to that of lotus leaves. Although waxing is also simple, wax is highly sensitive to temperature changes. If not applied properly, it may actually impair visibility, which is why this method isn't widely used.