But is this really true?
The reason why you may not want to: bathtub refinishing is a paint job applied to your tub. As with any paint, it can come off. Most bathtub refinishing isn't even the "dip" type of glazing (where the tub is removed, taken to a shop, and dipped). The process involves masking off the tub, sanding bad spots, and spraying with a paint gun.
The Experiment: Comet on a Reglazed TubNearly 2 years ago, I decided to start using abrasive cleaners such as Comet on my refinished tub. At the time, I had no idea how long I could do this before I would lose my tub's refinished surface. I figured I had one year, two at the most.
Two years later, the finish is still holding firm. The bottom part where you stand is no longer glossy, but it was not glossy when I began. I clean it once every two weeks. On the glossier parts, such as the sides, that don't get caked with impossible gunk, I lightly use abrasives or one of those soft cleaners.
Yes, to be prudent, you should avoid using anything abrasive on your reglazed tub--either abrasive scrubbers or abrasive cleaners. I am not advocating that you switch over to abrasives. I have a throw-away tub, one that I wouldn't mind replacing, and I have treated this as an experiment.