You're all gonna think I'm nuts, but for serious water spotting on glass, I've had great success with 000 steel wool, chrome polish, a little water and my trusty PC7424. We have extremely hard water and harsh sunshine where I live so waterspots are a constant problem. I once did this guy's 2002 PT cruiser. The water spots were unreal. When I asked when he last washed his cruiser, he said 2 weeks......2 weeks after he bought it!
I have tried acid, vinegar, Glass Spot Remover (GSR), clay bars and other stuff on tough industrial strength waterspots without satisfaction either because they left the spots or because of scratching.
Once I tried the steel wool, I was hooked. This is what I do: I'll cut a piece of steel wool and place it on a used PC foam pad. Place about a tablespoon of chrome polish on the wool/pad then and a very light spritz of water on the glass. Very little, not enough even to create drips or runs.
Then I place the pad and the wool with polish on the glass at the lowest speed setting to distribute the polish around the glass surface and the pad. Make sure none of the steel wool is showing from under the pad. Once this is done and the wool is firmly attached to the pad, I'll crank up the speed to "5". As the glass begins to dry out, I'll add another spritz of water if the spots aren't totally off yet.
Once it looks like most of the spots are off, I'll rinse the glass and use a water blade/squeegee to dry the glass. Unless the glass is completely dry, you will not be able to tell if all the spots have been removed, so I don't use a towel to dry the glass, always the blade. Repeat if necessary.
Amazing, scratch free results.
A few caveats:
1) If you have too much water or polish on the glass, the polish will fly all over the place. While not a big issue, it is a waste of product. If the water has evaporated and you cannot see through the glass, you are using too much chrome polish.
2) Sometimes there will be wool scattered like fine particles of dust, especially if you use higher speeds. Be sure not to get this dust into your MF, other pads etc. I always use copious amounts of water to make sure all the steel wool dust is washed away from the car once the polishing is done.
3) For obvious reasons, you will never use this pad for anything but glass polishing. It will get the pad all black so it's easy to tell which pad had the wool.
4) It doesn't take much steel wool for great results so if you're not sure how much to use, err on the side of conservatism. If you put too much on there, the wool will end up all over the car and you.
5) Tough spotting will still require patience and time.
6) I have tried this without the PC but left scratches. A PC or similar random orbital polisher is a must.
7) This is only for use on exterior glass. Not plastic (back window on some convertibles for instance) not paint, and not the interior glass.
