A chipped bathtub allows microbes and other elements to penetrate beneath the surface, damaging the tub badly if not repaired immediately. If you have an iron bathtub with chipped enamel, you might also have issues with temperature loss and rust. Instead of getting a new tub, look into repairing the damaged area and saving some money if the damage occurred recently.
Sand the affected area with 600-grit sandpaper and wash the area with soap and water to remove the dirt within it.
Squeeze both components of epoxy from each of their tubes and mix the solution with the plastic mixer provided in the package. If you didn't get a plastic mixer, use the butt of an old toothbrush.
Apply polyester filler to the sanded chipped area according to the instructions on the canister. Usually, you only have to apply the cream until it sits evenly on the surface of the tub. Wait about two hours before continuing.
Apply epoxy on the surface you just repaired. Use a painter's brush for this task to get the best results.
For best results, don't use quick-dry epoxy. If you must use quick-dry epoxy, follow step 2 after you finished applying the polyester filler.