What is the method of using toothpaste to prevent rain on rearview mirrors?

[DeGabriel]

Evenly apply toothpaste or soap on the side window glass of the car, wait for a while until the applied soap hardens, then wipe it clean with a towel to solve the problem. Spray glass water repellent evenly on the car windows and rearview mirrors, and a protective film will form on the surface of the rearview mirror. This protective film also has hydrophobic properties. If the glass on both sides of the car fogs up, turn on the car's air conditioning defogging function and adjust the air outlet angle towards the glass. For the problem of fog and water droplets on the rearview mirror, if there is a rearview mirror heating function, turn it on and it will effectively remove the fog within 3-5 minutes.

[Deanna]

Last time it rained and I couldn't see the rearview mirror clearly, I tried the toothpaste rain-proof method: first, I wiped the mirror surface spotlessly clean, not even leaving fingerprints. Then, I applied a tiny amount of regular white toothpaste, spreading it in circular motions with my finger or a soft cloth, just like applying a screen protector to a phone. After letting it sit for five minutes until semi-dry, I gently wiped off the toothpaste with a wet wipe and finally polished it to a shine with a dry cloth. The principle is that the silica in the toothpaste fills the tiny gaps on the mirror surface, causing rainwater to bead up and slide off. However, never use toothpaste with abrasive particles, as it can scratch the mirror. My test showed it could last through two light rains, but it became ineffective after washing the car, making it suitable for temporary emergency use.

[Robyn]

As a veteran taxi driver with ten years of experience, I’d like to share a practical tip: Pay attention to the details when using toothpaste to prevent rain on rearview mirrors. Choose paste-type toothpaste over gel-type, and avoid colored toothpaste if you have a blue car to prevent staining. Before application, thoroughly remove any oil film, or water droplets will still cling. Focus on applying it to the upper half of the mirror, as that’s where rainwater mainly accumulates. After applying, don’t rush to wipe it off—let it air-dry for ten minutes for better results. During rain, you’ll indeed see water droplets rolling off smoothly, but the effect won’t last beyond three heavy storms. Compared to professional rain repellents costing around 30 yuan per bottle, toothpaste is a zero-cost solution. Just avoid applying it too thickly at night, as it may cause headlight glare to scatter.

[EzraMarie]

An old folk trick my elders taught me: Applying toothpaste on rearview mirrors to repel rain is super simple. After cleaning the mirror, squeeze a pea-sized amount of toothpaste and spread it evenly—an old toothbrush works perfectly. Let it dry in the shade, then polish with newspaper; the ink makes the surface smoother. It’s the same principle as using toothpaste to remove water stains when washing dishes—it creates a hydrophobic layer that repels rainwater. I tried it during the plum rain season two years ago, and it worked flawlessly in light rain, though water droplets slid slower during heavy downpours. The best part is you can reapply anytime—I always keep a small tube of toothpaste in my car for emergencies.