Bathtub refinishing can be avoided with acidic cleaners. Otherwise, an epoxy paint can do a good job. Finally, call a bathtub reglazing and lining company.
A product often forgotten about is an acidic surface cleaner, like C.L.R. or IRON OUT. They use mild acids to dissolve calcium deposits unlike most other home cleaning products. These cleaners have saved more bathtubs, sinks, or humidifiers than I can count. Otherwise you may be ready for the refinishing job.
If any refinishing is to be done, you are going to do it. That is why I’m here. The product of choice is two-part epoxy paint. It is a most durable finish. It’s easy to mix because one can is half-empty and the hardener is simply poured into it and mixed thoroughly. Some set time is required for the mixed epoxy to combine before application.
Preparation of the surface usually calls for wetsanding with 400 grit wet-or-dry sandpaper. Simply wrap the sandpaper around a sponge and dip it in some water. Then dust over the entire surface to be painted with the wet sandpaper. This will dull any of the porcelain finish so the epoxy can adhere better. Rinse very well and dry thoroughly.
Applying the epoxy usually requires some prior painting experience in order to achieve a smooth finish. Take your time starting at the back edge of the tub applying the product evenly, not too thin as to leave brush strokes, and not so thick as to let it run. Ideally, you won’t have to go back and re-brush over any areas over ten minutes old. That’s when it will be getting ‘tacky’ and almost impossible to brush-into without leaving a worse mark.
Vapors from the drying epoxy are strong. A fan in the bathroom window blowing out will help immensely. Let it draw warm dry air from the house through the room and push the stinky air out.
Or call a tub glazier and a tub liner company. Get prices and guarantees from both and make your choice from there.
Keep in mind none of these repairs are as good as the original porcelain finish. Also, your cleaning products will have to change to milder ones with fewer abrasives in them so they won’t scratch the new surface. Proper maintenance will help you enjoy years of future use.