Ever wonder how RainX works?

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Glass is mostly silicone dioxide, which means the molecules are overall polar (unequal distribution of charge as a result of the atomic structure). This polar surface can be overcome by doing some organic chemistry, called silanization. Adding certain compounds, like hexamethyldisilazine adds non-polar group to the glass surface.

Remember, water is a polar molecule. Like attracts like. By adding a non-polar functional group to the glass structure, the water beads and is repelled.



Image: Glass (polar)+ RainX (adds CH3 non polar groups)-> Beading water (repelled by non polar groups)!
 
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Interesting. Never looked at the science behind Rain-X. I use it on my Semi Truck every time rain is forecast along my route. I end up not using my windshield wipers AT ALL during light showers because the water flies off and the beading action makes it see thru. Idk how people drive without it.
 
Originally Posted By: FordBroncoVWJeta
I feel like i'm back in math class. Even though you explained everything, I feel more stupid than when you began.


Never to old to learn!
 
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Originally Posted By: Scienceman
Originally Posted By: FordBroncoVWJeta
I feel like i'm back in math class. Even though you explained everything, I feel more stupid than when you began.

Never to old to learn!


Agreed.

Even though chemistry doesn't come naturally,
I understand how polars work and I get the Gist of it.

Thanks for posting!
 
You've just ruined it. I thought it was magic.

They're going to try and sell that stuff in Southern California but they're still waiting for it to rain hard enough to get windshields wet. Their expectations are high. Last year it rained so hard once that several puddles formed. Maybe they'll try again next year.

They were going to push the idea of keeping the windshield clear of snow but they couldn't find anyone that had ever driven in the snow.
 
Originally Posted By: FordBroncoVWJeta
I feel like i'm back in math class. Even though you explained everything, I feel more stupid than when you began.

Water is made of polar molecules. So is glass. Polar things are attracted to each other. So, when water lands on your glass windshield, it more or less stays there until it's wiped off.

RainX is made of molecules that have a polar side and a non-polar side. When you put it on your windshield, the polar sides of the molecules stick to your glass -- because, again, polar things are attracted to each other. But that means the non-polar sides end up facing outward. So, when water lands on them, it lands on the non-polar side. There's no attraction there, and the water just slides off.
 
So per the post and the pics, RainX is actually a chemical treatment of the glass, rather than a coating.

I thought that with all the fapping around trying to buff it out that it was a coating...then thought that the washer additive wasn't useful for the same reason.

Thanks for the post, that's pretty cool...I've always been a user of the product, as it works.
 
Originally Posted By: Shannow
So per the post and the pics, RainX is actually a chemical treatment of the glass, rather than a coating.

I thought that with all the fapping around trying to buff it out that it was a coating...then thought that the washer additive wasn't useful for the same reason.

Thanks for the post, that's pretty cool...I've always been a user of the product, as it works.

Oh wow -- you're right.

I retract my previous post. Hadn't looked at the diagram closely. Epic derp.
 
Originally Posted By: Scienceman
Originally Posted By: FordBroncoVWJeta
I feel like i'm back in math class. Even though you explained everything, I feel more stupid than when you began.


Never to old to learn!


"TOO" old to learn
56.gif
 
Originally Posted By: Papa Bear
Originally Posted By: Scienceman
Originally Posted By: FordBroncoVWJeta
I feel like i'm back in math class. Even though you explained everything, I feel more stupid than when you began.


Never to old to learn!


"TOO" old to learn
56.gif



You caught me! Never said I loved English!
 
Just did both cars yesterday prior to winter driving. I've found it much easier to do when the temperature is around 50F out.

Thanks for the explanation.
 
1) 4WD said, "...slime-X..."
I've heard may say that about Rain-X. Some also say it globs up on the wipers.
I DO NOT understand. Rain-X is so thin. I can't see it accumulating anywhere - anyhow!

Even if it was 150℉ I can't see how you could make it thicken up.

2) THE BEST Rain-X story was with my sister-in-law. I gave her car a treatment as a Christmas present. She watched me apply it just before leaving for home-a 230 mile trip.

It rained the whole way and the stuff worked marvelously.
 
Rain-X was developed by UNELKO Corp. in the early 70's and sold in late 90s to Quaker State. UNELKO then developed more similar products, RAIN CLEAR being their new formula of "Rain-X". I knew this history lesson because we used RAIN CLEAR as a mold release in a polyurethane manufacturing process and our chemist knew the chemist/owner/inventor of Rain-X. Rain-X applied to optical glass molds would not release the cured PU parts but Rain Clear would, obviously a different formulation and anecdotally could indicate that R/C is slipperier than R-X. UNELKO(.com) has a whole range of products that seem to be science driven, I've tried a couple and seem to work well, but it's hardly a household brand.
 
The original formula used isopropyl alcohol, the newer stuff uses ethanol. Doesn't work as well either.
 
As someone who spends a ton of time on the road in some of the worst weather I won't use anything else. I hardly need my wipers because of the coating the Rain-X Windshield washer fluid leaves on there with regular use.

I also calculated I use far less windshield washer fluid of the cheaper variety to make the higher cost worth it.
 
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