Rain X Window Treatment

[rguzz]

It does cloud the windshield some which is noticeable at night, I agree. This might be attenuated (fancy!) by making sure the windshield is super clean as in the directions before applying. Love the way it deflects water, but trade off for me was loss of clarity while driving at night. Left a film I could see.

[MrAl]

I've used Rain X but I don't like the glare it gives you in the eyes from the road lights... best to have good working wipers.

Hi,

Thanks for the replies from everyone.

The glare was what i was afraid of. I'll have to see how it affects my car at night but i'll have to wait to see that.
Even before this there seemed to be quite a bit of glare at night i thought might be because of the angle of the windshield which is significant.

I did notice already that the water beads up, but that was when cleaning off the window with some cleaner. THat's another thing, i wonder if regular glass cleaner takes it off so it would have to be reapplied.

[sagewhitesage]

It works great.

I use it religiously on my frameless glass shower walls to prevent the bad hard water in creating permanent spots. These framelass glass shower are beautiful as long as there are no etch long term water spots on it.

[MrAl]

Hi,

I noticed something interesting yesterday. We had no rain but there was rain left from earlier and so there were some water beads on the windshield.

When i applied it for the first time i only did certain sections so i could see any difference once it rained. Very interestingly, the places where i applied it had some small water beads but the places where i did not apply it there were no water beads or any water at all. That tells me that the water dried faster where there was no application and dried slower where there was an application.

Not that it matters that much but it is a little interesting. I guess when the water can not spread out as much over the surface it naturally can not dry as fast. Since that's not really a concern, this is sort of just an interesting little factoid that's about it.

[matthew1]

There's more surface area on water when it's flat. Thus more evaporation.

A bead is roughly half a sphere, which keeps a little less than half of the surface area of any given about of water from evaporating (it's against the glass).

[abscate]

It's actually exactly 1/3 less, according to my friend Archimedes, but thats mere quibbling over pi.

[MrAl]

Hi,

Thanks for the interesting view on this. I am happy to see you guys are into this sort of calculation and understanding of nature.

Yeah i guess we can approximate the shape as a half of a full sphere which would have exposed surface area 2*pi*r^2 and hidden surface area a full circle which has area pi*r^2, and so the ratio of the full circle area to the total half sphere area would be 1/3 exactly. So for a flat area of 3 square inches the flat area has the entire 3 square inches exposed while the half 'sphere' only has 2 square inches exposed. Thus, the flat area evaporates faster.

However, that tells us more or less that the rate of evaporation is greater for the flat surface and what we might also consider is the volumetric view which is also interesting.
For a flat surface column of water the rate of evaporation would be about the same for all time, With the bead however the bead surface area keeps getting smaller and smaller, so the time for the bead to evaporate completely could be much longer than the ratio 1/3 makes it look like.
This makes sense because if there was only a 1/3 difference in time i would probably have to be very lucky to have went out to the car at the right time, but if the time difference was much longer the probability of me seeing that at the time i went out there would be much greater, and that's how i was able to observe this.
We could do this calculation i guess, but it seems obvious now that it will be much longer for the bead.

So what do you think?

Back up your opinions with any relevant equations and show all work (just kidding)

[matthew1]

Turn on the Lava Lamp and light up the joints... this could get interesting.

[rspi]

I use to use it when I lived in rainy Arkansas. Didn't really like it on the windshield, loved it on the back and sides.

My observation was that it would fill in the minor imperfections on the glass surface. Making the water run off better. The down side was the wipers sticking to the smoother surface, mainly where they changed directions.

The water would blown off the sides very well. It was easier to clean the glass. Also easier to clear off snow and ice.

The only time I had an issue with fogging or the look of a film was when I didn't buff it enough. Hard on the elbows, Karate Kid...

[utilityaudio]

make sure your glass is very clean, and dry before applying (I even use some 0000 steel wool as the last step), and then work in sections and use clean paper towels to apply and dry ones to buff it until you can't see the film anymore.