There are many people with foggy glasses wearing masks during Covid19. Wearing a mask is essential to prevent the disease, so people must wear a mask all the time. Mr. Byung Muk Won, Sungkyunkwan University Associate Professor, said the reason for the misting of glasses is that the air in the warm body meets the cold glass surface and the water vapor condenses, causing tiny droplets of convex water to stick to the glass surface and scatter light. The convex water droplet attaches to the glass surface at a contact angle of about 40 degrees, acting as a convex lens. Flattening the convex water droplets can prevent misting. The contact angle of the water droplet is close to zero degrees and is called ‘super hydrophobic’. The smaller the energy of the two materials in contact, the smaller the angle of contact. If the convex water droplet turns into a flat water film, it does not scatter the light and provide clear vision.
In order to do this, Professor Won suggested the following tips:
- You can easily buy an eyeglass cleaner that costs less than 10 dollar. Simply clean the eyeglasses with the wipe. It will prevent misting up for about 3 to 4 hours.
- Use the neutral detergent in the house, sprinkle it lightly on the surface of the glasses, and wipe it with a clean cloth. This will give a similar effect. Surfactants in the detergent make the contact angle close to 0 degrees, preventing misting for about 1 hour.
- If you left the house in a hurry, you can wipe your misted glasses with a clean cloth. This will form biofilms and temporarily prevent water droplets from forming on the glass surface. It works for about 30 minutes.
- There is also a way to prevent misting by making the contact angle close to 180 degrees, but this method is not suitable for daily use because the glass surface must be machined.