Recently I did a really stupid thing. My toilet at home stopped up and the plunger would not do the job. I had a spring steel plumber's "snake" that I had used on drain pipes before and grabbed it without thinking. I finally cleared the obstruction, but severely scratched the porcelain in the commode. I had just about decided that I would have to replace it, but decided to do what I should have done in the first place, Google it! The first thing I saw was a recommendation to use "Bar Keeper's Helper". I thought that was ridiculous, that a cleaner would never do anything for those terrible scratches, but I went to Lowes and bought a can. After finally getting all the water out, I used a wet sponge and applied the "helper". I WAS AMAZED! All the scratches were GONE! I still don't understand how it works, but as long as it does I won't worry about it. After that success I got excited and decided to try it on some stains on the bottom of our fiberglass tub enclosure that we had tried everything possible to remove. This time it remove about 95% of the stains, enough that no one will notice them! I'm telling you folks, this stuff is great! Maybe all you guys already knew about this, but you didn't tell me!! Hope this helps some of you! Good luck & God bless!