Anti-Fog Mirrors: How do they work?
Steamy condensation is one of the most frustrating aspects of utilizing a mirror in any environment, which means it’s no surprise to many that anti-fogging agents have been fiercely sought after by chemists and engineers for decades. Today “no fog” mirrors are readily available commercially and privately, but the folks at Superior Mirror bet you’re wondering just what makes them work?
Scientifically, the problem is surface tension. Water molecules like to cohere together, but molecules on the surface do not have like molecules surrounding them on all sides, so they have stronger cohesion with those that remain, forming a powerful attraction. Because the water’s surface is so thin however, it appears translucent, creates the “fog” we see on mirrors. Temperature matters too; as hot water vapor hits the cooler surface of a mirror, surface tension goes up dramatically along with cohesion. Even wiping off the mirror is only a temporary, as new water vapor quickly replenishes the thick surface tension.
So how do we fight it? There are two ways to battle the Fog: surfactants and hydrophilics. Big words each of them, but for our purposes surfactants minimize surface tension of the water to prevent cohesion, and hydrophilics increases the surface energy to help disrupt the bonds of the water molecules themselves. Some common surfactants are things like laundry detergent, shampoo, and other chemicals that disrupt surface tension and prevent fog, but they are water soluble by design and tend to smear with long-term use. That’s why manufacturers utilize hydrophilics more often (in the form of polymers, titanium dioxide, and others), whether as a chemical application of to a mirror’s surface or building it into the design itself. It lasts much longer and is not subject to dissolving with prolonged exposure to moisture.
But there you have it: anti-fogging solved with science! Is there any other kind of problem solving these days? Thanks for reading Superior Mirror’s blog and keep your eyes peeled for more mirror facts in the future!