It’s all in the glass

Whether it is raining, or dusty, the driver of a vehicle must have a clear view. Which means nothing must stick to the glass and make it opaque. The two most common things that stick to windshields are water and dust. Now, as you might know, both carry a small amount of static electricity.

Repelling water

As you might have read in our article on furniture polish, dust settles on places that have opposite static electricity. So does water. (That’s why it is dangerous to touch electric appliances with a wet hand.)

Just as furniture polish, if the windshield is coated with an antistatic, it will repel water. But since the driver has to see through a windshield whether it is clear, dusty or rainy, the antistatic must be completely transparent too.

Car manufacturers do this by coating windshields with special chemicals such as siloxanes, mixed with industrial adhesives. These form a very thin film on the glass. They stick tight to the glass and are completely transparent. What’s more they repel water! That’s why it’s easy to clean the water of them by simply wiping with a rubber wiper.

Car manufacturers coat windshields with special chemicals such as siloxanes, that are antistatic and yet completely transparent.

Make a water-repelling slide

You can try this small experiment in your lab. Take a microscope slide and put a small drop of mineral oil on it. Spread it all over the slide in a smooth layer. Now put a drop of water on it. You’ll notice how it rolls off the surface without sticking.

Now wash the slide with soap till all the oil is removed. Let the slide dry in air (don’t wipe it dry). Not put a drop of water. You’ll observe how it spreads and sticks to the glass. You just saw how an antistatic coating works!

In fact, because scientists need specimens to cling tightly to their slides, they always insist on having completely clean, non-stick slides, the very opposite of windshields.