Things You'll Need
Medium grit sandpaper
Spray stone finish
Small paint roller
Small paint spreader
Refinishing a cultured marble bathtub can take several days to accomplish. Damaged or aged marble can be refinished with a few supplies that can be purchased from most any building supply or craft supply store.
Clean the bathtub thoroughly with a sponge. Ensure that all buildup from water and soap residue is removed.
Sand the bathtub lightly with a medium grit sandpaper to smooth the marble. The inside of any indentations should be sanded as well.
Tape along the edges of the bathtub, near the door and at the top of the marble. Any places where the marble meets another surface should be taped.
Wipe the bathtub thoroughly again with the sponge to remove all of the dust from sanding.
Apply a coat of primer to the bathtub using the small paint roller, following the manufacturer's directions.
Spray the bathtub with the spray stone finish, following the manufacturer's directions. This finish can be either the same color as your bathtub or you can choose a different color. Begin working at the top of the bathtub and work down toward the bottom, ensuring that an even coat is put on the entire bathtub. Allow the spray stone finish to dry accordingly.
Follow the manufacturer's directions exactly when dealing with the polymer resin. Using a disposable cup, pour a small amount of polymer resin into the cup and pour it down the wall of the bathtub. Begin at the top and work toward the bottom. When the polymer resin drips, use the paint scraper to push the polymer resin back up. Apply a generous layer to the entire bathtub and then allow it to dry per the manufacturer's directions. Any indentations in the marble will no longer be visible because the polymer resin will fill the damaged area.