You would think that “Fogging up your windscreen” would be a thing of the past by now. Certainly, the smeary vision we put up with as we wipe the inside of our windscreens/windshields with the back of our gloves, or anything else that happens to be lying around, does not assist in driving safety, quite the opposite. And, trying to clear the “fogging” while actually driving is an accident waiting to happen.
For many years, I had forgotten all about this menace to driving safety. It only happens occasionally in the Caribbean when the combination of heat, heavy rainfall and air conditioning can produce the same effect. However, winter in the northern climes produces the challenge of being able to see through your windscreen far more often. A smeared windscreen coupled with headlights reflecting off a wet road must contribute to more accidents than almost any other cause. It was thus with great interest that I read of a possible solution to this pervasive problem.
Electric wires running through the rear windows of vehicles sort-of-works but, if you tried that sort of solution on front windscreens, you would only exacerbate the problem. Peering through lines of small horizontal wires would probably be more distracting than smearing the fogging with your hand.
Enter a coating that can be applied to glass or plastic and can even be embedded in those materials. The coating has been described by its Swiss inventors as a gold sandwich. The “bread” of the sandwich is two layers of titanium dioxide, each three nanometers thick, and the filling of the sandwich is a four-nanometer-thick layer of gold filigree.
When gold is deposited on a surface at random, it first forms miniature islands. These gold islands initially act as an insulator. When more gold is added, bridges between these islands begin to appear, which allow heat to flow between them. At a certain point all the islands are joined up by bridges, producing the filigree network. That network can absorb the regular infrared part of daylight (only 40% of solar radiation is visible light, infrared is 50%). That absorption produces heat in the filagree, which prevents fogging. Admittedly, solar radiation on a cloudy day is reduced, but it still produces enough heat in the filigree to clear the fogging.
The only problem, obviously, is that is doesn’t work at night, since there is no solar radiation, or very little, so this technology only solves half the problem. Actually, it only solves less than half the problem, because fogging windscreens at night are far more dangerous than those that occur during the day. However, at least the new Swiss discovery is better than nothing.
Acknowledging this “night” fault in their discovery, the Swiss inventors of this gold filigree sandwich are now thinking of applying it to other surfaces, such as spectacles.
Apparently, even though they are using gold, the amount required is so little that the cost is minimal, and so it might make economic sense.
Let’s hope they can take their discovery further and come up with a sandwich that works at night as well. We wait with baited breath.