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Author Topic: How does rainex work?  (Read 10337 times)

jon

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How does rainex work?
« on: 07/07/2011 17:30:02 »
jon  asked the Naked Scientists:
   
Here, in the States, we have a product called RainEx.  You put it on your windshield and then rain beads up. 

It turns out that if the only light source is directly in front of you, all of the water droplets vanish at night.  If you drive under a street lamp, then you can see the water droplets, but just for a second, until the light passes.  Perhaps it would be interesting to understand the physics behind this product.  I assume it has to do with how water is reflected and refracted at different angles to the spherical droplets.  You could set up a Kitchen Science demonstration (excuse me: experiment!) fairly easily.

Jon

What do you think?
« Last Edit: 07/07/2011 17:30:02 by _system »


 

Offline CliffordK

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How does rainex work?
« Reply #1 on: 11/07/2011 19:00:03 »
I've heard of the product, but haven't used it.

I believe you apply a wax to the windshield.  It would create a hydrophobic surface causing the rain droplets not to stick to it, and run off quicker.

You could probably get a similar effect with other types of waxes, and perhaps greases.  However, a windshield application would need a very clear wax that would not change colors with time.
 

Offline SeanB

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How does rainex work?
« Reply #2 on: 11/07/2011 19:35:49 »
It works very well, as the rain hits the glass it beads up and is blown away. It works best in rain that is moderate to "lake falling out the sky", provided you are travelling above a speed where the water is blown off the glass. In light rain, or when you are slow or stopped, the glass will be covered with beads, but the wipers will remove it with a single wipe. Most of the time you do not need the wipers at all.

As far as I know it is made from a refined bee wax dissolved in methanol, and a single application will typically last for months.
 

Offline Geezer

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How does rainex work?
« Reply #3 on: 12/07/2011 03:59:26 »
Which reminds me - I bought some of the stuff about two years ago! I'm sure I'll get around to putting it on the car any day now.
 

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How does rainex work?
« Reply #3 on: 12/07/2011 03:59:26 »

 

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