Instruct: Classify the given Amazon review into its appropriate rating category
Query: Works for glass, but didn't work on stone.

This seemed to work well on glass to get rid of the stains, but when using it on tile and stone it did not work as well. It did get rid of the big white stain, but left an outline of the stain that I was unable to remove. I ended up having to use an acid etch to remove everything and then re-seal the stone. The glass walls everything came off with very little scrubbing. I will continue to use this for glass, but if the stains are really thick or old, sorry even on glass it will not remove them. I tried to use this to remove hard water stains on a glass sink and the hard water deposits just laughed at this stuff. It was as effective as using straight water on them. I think with regular maintenance on a newer shower door, you will have good luck. If you are only trying to clean up old tough deposits, look elsewhere.