BUFF-IT-FREE: It was developed for newer fixtures that don't have the great finishes that used to be on bath fixtures. It is also used for clear shower doors. Sprinkler spotted windows as well as acid rain spotted car and home windows. If there is a large amount of glass to be cleaned or there is a very bad build up, you may want to apply the BUFF-IT FREE with an orbital buffer. It will leave a finish that will help to protect the glass. Or if there is a very heavy build up you may want to try "0000" steal wool. If used with the BUFF-IT-FREE it'll make short work of those especially hard to remove stains. It'll work like magic. It will also leave a finish that will help to protect the glass from future heavy build up...use BUFF-IT-FREE with an orbital buffer on boats. It will remove all the oxidation. Leave BUFF-IT-FREE paste on for a few minutes letting it soften the minerals. Do not let it dry on the surface to be cleaned. When applying, pour paste on soft cloth and Apply in circular motions. Let sit for 5-7 minutes careful not let it dry or the minerals will soak right back on the surface.