Posted by Dean Smith on October 10, 19100 at 11:55:52:
We had some bad stains (rust colored, but probably well water related rather than rust, per se) in our fiberglass pan/ceramic tilie shower that wouldn't come out with ANYTHING.....until we tried a product called ZAP! I found it at Sam's Club, thanks to one of those usually annoying videotape sales spiels they have, and it worked absolutely perfectly. You can use it full strength (which I did on the floorpan) or dilluted (grout), and it worked INSTANTLY on the grout and with a minimal amount of scrubbing on the floor (which was really bad). It cost about $10.00 for 2 12 oz. bottles (of course, you have to buy 2 bottles at Sam's!), and I used less than 1/2 a bottle on the whole job. Odor wasn't too bad, and it wasn't too caustic, as gloves were only recommended, not mandated! For homeowners & professionals, I cannot recommend ZAP highly enough!!!!!!!!!!!!!