You will need to prepare your bathtub before it can be refinished.
Remove the Existing Caulk and Surrounding Fixtures. This means removing the old caulk along with fixtures like train traps and plug holders.
Clean the Tub and Any Other Surfaces You Intend to Paint
Repair the Surface of Your Bathtub (If Necessary)
Cover Any Sections You Don’t Want Getting Painted
Prime Your Bathtub. Grab your brush, get some paint on it, and cut in any corners of the path that you cannot reach with your roller.
Once the bathtub has been primed it’s time to paint it.
Let the paint dry for at least 2 days before using it (see also the paints manual)