Why does a mirror fog up after a hot shower?

The basic mechanism why shower mirrors fog or get cloudy during a hot shower all comes back to condensation. In simple terms, condensation happens when warmer humid air comes in contact with a cold surface.

You could be asking “Why is there fog in my bathroom mirror?”

My best answer is the “fog” consists of tiny droplets of water that form on the cool surface of the mirror. Why does this happen ? Some of the hot water from the shower evaporates, so the air in the bathroom contains a lot of water vapor.

Why do bathroom mirrors fog up?

As you’ve probably noticed when trying to check your appearance in the mirror after a steamy shower, the bathroom mirror fogs up so much you can’t see yourself. Steam in the air turns into condensation — tiny water droplets — on the mirror glass, which in turn distorts light enough to make the mirror hazy.

Why does the mirror in the bathroom get cold after shower?

Some of the hot water from the shower evaporates, so the air in the bathroom contains a lot of water vapor. When the water vapor contacts cooler surfaces, such as the mirror, it cools and loses energy. The cooler water particles no longer have enough energy to overcome the forces of attraction between them.

The reality is that your shower is a difficult environment and the surface of your mirror needs to be kept warm, smooth, and clean so it can give a clear reflection. Any scratches or surface pitting will degrade your mirror, as will any hard water deposits or soap scum residues.

Do fogless shower mirrors work?

But for it to work you need to be able to see yourself clearly so you need a mirror that isn’t fogged. Shower mirrors fog because the mirror surface is colder than the surrounding air, causing moisture to condense on the surface as fog. Fogless mirrors work by either warming the mirror or by using a surface treatment that resists condensation.

The most effective design is the Fog-Free Mirrors that use heating elements. It connects to your mains, often wired to a wall switch that turns on the heating elements when the bathroom light comes on. The heat generated reduces the temperature difference between the mirror’s surface and the fog from the hot water.