Glass Care

Water marks on glass could be rather annoying. Since glass is much harder than paint or clear coat on paint for that matter, removing water marks should be easier.

Good Glass Cleaner

Regular car shampoo should do a good job in cleaning all the glass in your regular wash. In fact some shampoos have some "wax" that will help windscreen repels rain droplets. However, if there is already water spots or marks on the glass, regular car shampoo might not do the trick. Then it is time to move on to more serious glass cleaners.

Get a glass cleaner that is meant for automotive. Try to avoid household glass cleaners as some of them might contain ammonia and acid that could be harmful to both your health and your car. Regular household glass gleaner with "colored" liquids could even stain your car.

What I have in my arsenal is Meguiar's Glass Cleaner and Stoner Invisible Glass. Both of these cleaners are colorless and contain no ammonia and acid. The material safety data sheets could be found here and here, These two glass cleaners contain alcohols. Alcohols are common in glass cleaners. They help in removing oil and give fast drying "evaporating" results. So a little bit if caution here. Try not to get them on your car paint as they would strip away wax and and sealant because of the alcohol content. Right, end of chemistry class. 

These two products smell the same. I could not confirm if they are the exact same product but if they are, the Stoner would be a better buy because of the lower price.

They claimed that they would not create streak marks. However, from my experience, they do streak no matter how many times I wipe with clean towels. The streak marks will become more apparent when the glass are fogged up in cold rainy weather. One other observation besides streak marks is that glass tends to fogged up easily after cleaning with these cleaners. I could not really confirm but it does feel that way.

Polish the Glass

Usually places like front and rear windshields tend to have more stubborn water spots due to their angles. If glass cleaners do not remove the water spots, then it is time to bring out the big guns -  compounds and polishes.

As usual, before any compounding it is wise to clay the surface. I follow the same routine for glass as well. I just do not want any contaminants to "clog up" my polishing pads. As I mentioned earlier, glass is much harder than paint. So we could use a more abrasive cutting pads.

One could use elbow grease or electric power. I chose electric power. I used my DA. Read about my hands-on with it here.

I so happened to have an Autoglym Car Glass Polish lying around.

Let see what the manufacturer has to say:

"Car Glass Polish is specially formulated to increase visibility through your windscreen for safer driving.

The easy to use, deep cleaning solution removes traffic film, grease, wax, nicotine, insects and water deposits.

Suitable for use on interior and exterior glass. If your windows are perspex, acrylic or plastic use Fast Glass instead."

As mentioned above, since glass is much harder than paint, I would normally use a microfiber polishing pad rather than my usual go to CCS pads.

Microfiber pads have thinner foam that would translate to more "polishing" power.

As usual, the pad needs to be primed (see here for more info on priming). Then spread the product using a low speed, say speed 2.

Once spread, turn up the speed all the way to 6 and start polishing in overlapping pattern in a small section, maybe 1/4 of the windscreen.

Half-way done.

Unlike Meguiar's Ultimate Polish, Autoglym Car Glass Polish does not turn clear after several passes. So, after a few passes, stop and wipe off to inspect.

NOTE: In is important not to let the product dry up else, it would be very hard to buff off.

Autoglym Car Glass Polish tends to be very dusty when buffed off. I guess it would be the case as with other glass polishes.

As for correction power, Autoglym Car Glass Polish is somewhat mild. Very stubborn mark like wiper "curve trail" would not go away. Normal water spots are no problem for it.

Actually, I do not think we need a special dedicated glass polish to do the job. Any regular car polish or compound could do the job. I guess the latter would be better as it is more aggressive and could get the job done faster.

I would highly suggest following the steps recommended by Larry from AMMO NYC here.

Once polishing is done, follow-up with an IPA (isopropyl alcohol) wipe. I diluted my 99.7% IPA in a 1 to 1 ratio with water. One could seal up the glass with any coating after that. However, I prefer not to put anything on my front windshield in fear that it would affect my wipers performance and fear of smearing. It is just personal preference.

As usual, the above are just my opinions. Choose a method that might work for you and happy detailing.