I’ve been using Cerium oxide for hard water removal these past couple weeks however I still have not gotten it down to be super effective. I can get all the hard water off but it takes several times of going over the window and can be a little time consuming. Does anybody know of any good videos on how to polish off hard water with Cerium oxide?
Polishing off hard water can be very time consuming. What polish are you using?
Their is a huge difference in cerium oxide grades. If you’re not using the right grade it could take twice as long. It could also be the polisher, if you’re polishing at the wrong speed it can add on to the time. Though I am not a big fan, that’s why they make acids, to speed up the process and combat different types of stains.
So I am using the cerium oxide that wcr sells. It is the orange one that came from crlaurence. Then I am using a porter cable variable speed polish/sander from lowes.
I put it on a low speed to spread the slurry out then turn the dial one less than the highest it goes.
It might take 30 minutes to do a 4 foot square of medium hard water.
( I know these are still probably vague figures)
Well that is the problem sir! You are doing it wrong and using the wrong products. If you have know idea what glass, cerium oxide and your pads grades are you can damage glass even tho your getting off the hardwater spots. Abrasions will be scene in the right light and then you will need to remove those as well… Using the wrong speed can effect it as well. Please leave it up to the experts or get the right equipment or knowledge to do the work. 
That is vague. To take hardwater off that is just a build up of lime build up only takes 15 mins with 50 pounds of square feet into the glass at 10,000 rpms. (If you get the window to hot it can crack or leave abrasion on the glass.
