Troy H

I rarely have to use my wipers. Rain-X and other products like it introduce foreign material to the glass and invariably wind up coating your wiper blades and making nothing less than a slimy mess of your windshield. How this is safer in the rain I'd like to know.

6sidua

put water in a clean drinking glass, the water level will curve up the sides of the glass demonstrating this attachment. the same happens on clean window glass. pour any oil into the empty glass and it will form a rounded surface (higer away from the edge) because glass is lipophobic.
when glass is coated with any "rain shield" product, the glass surface becomes hydrophobic so the water is repelled and beads. water now moves more easily off of the glass while driving, or with a squeege or blade. this is why commerical aircraft glass is coated to keep the water moving away in flight...

if you glass beads it isn't clean like you think but rather has a think molecular layer of something on it..

Seattle Scott

I thought most airplanes used "plexiglass" for the cockpit.

Troy H

2) My glass is regularly cleaned, polished and clayed and 3) People who ride in my car in the rain invariably comment on how the rain runs off the windscreen, usually with a comment like, "Did you just Rain-X your windshield?"

So, knowing how many people hate the streaking that occurs with windshield treatments, and knowing how crystal clear my glass is under all weather conditions, I see no reason to do anything but what I've been doing. By extension, I see no reason to recommend to this forum anything but what I've always done.

Troy H

Depends, but the glass windscreens are nothing like auto glass.

6sidua

just like all the other products for glass. most people just don't buff them enough to get the thinnest possible layer. but any polish you apply to the glass works like rainx... just under stand its the thin layer of oil molecules that make your glass bead.

if you really cleaned the glass like a suggested earlier, or with acetone (like when the autoshop cleans paint before spraying new) you would lose your much admired beading.

you seem to care about giving others the correct info so why not just try the experiment? see the difference between "clean glass" and treated glass.

Troy H

I put my steps in the wrong order in my previous post.

6sidua

We talk about glass from time to time when we discuss polymers, especially when we're talking about composite materials. Glass fibers are often used to reinforce polymers. But what is this stuff called glass? We use it with polymers a lot, obviously, but is glass itself a polymer?
Before answering that question, let's take a look at what glass is. The highest quality glass has a chemical formula of SiO2. But this is misleading. That formula conjures up ideas of little silicon dioxide molecules, analogous to carbon dioxide molecules. But little silicon dioxide molecules don't exist.


Instead, in nature SiO2 is often found as a crystalline solid. Every silicon atom is bonded four oxygen atoms, tetrahedrally, of course; and every oxygen atom is bonded to two silicon atoms. When SiO2 is in this crystalline form we call it silica. You've seen silica before. When you find big honkin' crystals of it we call it quartz. When we have a lot of little tiny crystals of it, we call it sand.

But this silica isn't glass. We have to do something to it first to make it into glass. We have to heat it up until it melts, and the cool it down really fast. When it melts, the silicon and oxygen atoms break out of their crystal structure. If we cooled it down slowly, the atoms would slowly line up back into their crystalline arrangement as they slowed down. (Remember, heat is nothing but the random motion of atoms and molecules. Hot atoms move a lot, cold atoms move very little.)

But if we cool it down fast enough, the atoms of the silica will be halted in their tracks, so to speak. They won't have time to line up, and they'll be stuck in any old arrangement.

We call materials like this amorphous. This is the glass that is used for telescope lenses and such things. It has very good optical properties, but it is brittle. For everyday uses, we need something tougher. Most glass is made from sand, and when we melt down the sand, we usually add some sodium carbonate. This gives us a tougher glass with a structure.


This is the glass you see everyday, in jars and windows, and it's the glass that is used in composites.
So is this a polymer or not? Usually it isn't considered as such. Why? Some may say it's inorganic, and polymers are usually organic. But there are many inorganic polymers out there. For example, what about polysiloxanes? These linear, and yes, inorganic materials have a structure very similar to glass, and they're considered polymers.


So glass could be considered a highly crosslinked polysiloxane.

"plexiglass" used to be a brand name for a particular product, plasticized lexan. now its used more generically and all safety glass in cars or airplanes still needs a hydrophobic coating to "bead up" water....

6sidua

just the same if water beads on your glass, there is a "film layer" deposited so "clean" it isn't

Troy H

it runs off pretty well at 500 mph.