Cleaning Glass

Glass Cleaner

What is glass cleaner made of? I requested MSDS from manufacturers. Here's what I found:


Glass cleaner ingredients, from MSDS:
waterisopropyl alcohol2-butoxyethanol (dissolution promoter)acetone (polar solvent)ammonia (emulsifier)PGME (polar solvent)other
Windex blue: * * *  
ClearVue Professional: *1-3%0.5-1%1-3% 3-5% 
Stoner Invisible Glass: ****   
Armor All Auto Glass Cleaner: *1-5%    propylene glycol butyl ether (1-5%)
Eagle One 20/20: **    glycol ether
Amway/Quixtar LOC Plus: * *  *propoxypropanol, propylene glycol butyl ether
Amway/Quixtar See-Spray: *** * isobutane (propellant), anti-fog agent
Westley's Glass Cleaner: *5-20%~5%   sodium alkyl olefin sulfonate surfactant (1-5%), other surfactant (1-5%)
3M Glass Cleaner concentrate:  20-40%20-40%20-40%   
Eimann Fabrik Clear Vision: *20-35%0.5-1%   methyl alcohol (10-15%)


The asterisks mean MSDS listed an ingredient, but did not specify concentration.

Since every conceivable cleaning agent (besides water) has OSHA-regulated exposure-limits, I assume MSDS is comprehensive -- there are no other magical ingredients in these glass cleaners. These glass cleaners are just mixes of common solvents.

I was surprised to see that ClearVue has the most diverse set of cleaning agents, which is probably most desirable -- a diverse set of cleaning agents is more effective against a broader spectrum of contaminants than a single cleaning agent. The problem is ClearVue is 90% water.

Rain-repellant

A few people in my family swear by rain repellant (Amway Hard Surface Protectant, or RainX), and See-spray which contains an anti-fog treatment.

According to MSDS, RainX consists of ethanol (1-10%), isopropanol (75-95%), polysiloxanes, and organosilanes. An organosilane molecule has two ends -- the "silane" end electrically bonds to surfaces like glass. Such a bond is not easy break -- organosilane treatments can only be removed mechanically, by polishing with an abrasive and taking off some of the glass with it. (Glass cleaner will not completely strip RainX from glass, though it will thin down a thick application of RainX.) The "organofunctional" end both links with other siloxane molecules, and serves an application-specific purpose: in this case creating a hydrophobic surface that repels water. The polysiloxanes promote crosslinking (applying a better film). Together, they make glass repel water.

RainX-type agents do seem to work as advertised, though it gradually degrades and must be reapplied. If it's not reapplied, raindrops will ball up on the glass but not roll off, which I find totally distracting. An old RainX coating is worse than no RainX coating.

For this reason, some people will like RainX and some people won't. To be safe, I would suggest only using RainX on your car's side windows. RainX works best on side windows because of the way the wind blows. RainX lasts longer on side windows because the coating does not get frequently rubbed by wiper blades. After a few months, if you decide like it and don't mind maintaining it, go ahead and put the RainX on your windshield.

Anti-fog

Anti-fogging agents work in an opposite way. Instead of repelling water, they modify surfaces to attract water. Thus, when a window fogs up on the inside, the moisture droplets spread out and merge into a thin sheet. And a thin, flat sheet of water results in less optical distortion than a layer of micro-droplets of water. The condensation is more transparent, so the fog becomes "more invisible."

My experience in using See-spray has been that the anti-fogging agent loses its clarity unless cleaned (with ordinary glass cleaner) and reapplied at least weekly. I do not know why, but my best guess is that the anti-fog layer simply attracts dirt. Considering their high-maintenance, I do not recommend using an anti-fog agent on your glass. To prevent 90% of the fogging problem, I recommend just keeping the glass really clean.

Towels

I used to clean the windshield with paper towels, but today I use crumpled newspaper on the outside, and microfiber on the inside.