Old Tub, New Finish
Your success in a tub-reglazing project depends on how well the surface is prepared before reglazing.

The porcelain has to be thoroughly cleaned and then etched using strong acid so that the new glaze will bond well. Finally, the refinisher sprays on two to four coats of urethane enamel and then dries and polishes it. The whole process takes about a day.

For a tub liner, the local installer sends exact measurements and a picture of the tub to the factory. There the right mold is chosen and used to vacuum-form a sheet of ABS acrylic, the same material used for football helmets. Back in the bathroom, the installer trims the liner, slides it in like a glove, and then caulks and seals it in place.
Liners are much more durable than a reglazed surface, but they cost from $800 to $1,000 installed. Reglazing costs from $200 to $500, but even with care, it will last only about 10 years.
Because of the tricky prep work’s importance to a successful reglazing, it’s advisable to hire professionals who stand behind their work with at least a five-year warranty.