Whenever you remove stains or scratches from glass you have made it extremely vulnerable for scratching or more stains to lock on stronger than before. I am starting to experiment with a new sealant designed specifically for glass from a company called Nanovations. It has been tested for a longevity of two years. I have also discovered that it stands up to scratching. And have begun writing articles about it in my blog. All of the contact info is there including a code to use to get a free sample.
I got a sample of that and applied it to my windscreen, it does not protect from chips tho as I now have one in my glass from driving on gravel roads for he past few months.
I have not cleaned my windscreen since I applied it when it rains it gets all clean then it beads I don’t even need to use the wipers to be able to see clearly.
I plan to test it on some shower screens.
No unfortunately I don’t know of any nano-coating for glass that will protect against chips from small rocks. It does a great job protecting against scratches. I can’t wait to get my video editing software working again so I can show this. Also it does have a longevity rating of two years. And for the new building market it will have a warranty of ten years. Which has already been offered in Australia. Check out the Socar Tower in Australia. I will be writing a post about this project from October 2013. And will be including the warranty on the Glass Smart blog.