Prepare the chip by removing the enamel all the way down to the surface. Use a sharp blade, like a utility knife, to cut a V shape around the chip.
Cut the spot with the knife until you get all of the enamel off of the tub in a triangle shape. Wipe away the dust.
Use a clean rag dipped in acetone to clean the surface of the chip. This will remove any remaining particles from the surface of the tub.
Mix the repair paste. Repair kits are available for most tubs in a range of colors.
You can order a repair kit through the manufacturer or online. Choose the color that best matches your tub’s finish.
Mix the paste according to the directions that came with your kit to form a putty.
Match the color of your tub. Use the kit’s included toner to add white or black to your paste until you have matched the color of your bathtub surface.
Mix the toner and paste thoroughly.
Use a putty knife to apply the paste over the chip. Overfill the chip slightly.
Allow the paste to harden for one to two hours.
Sand the repaired area to smooth out the surface. Start with 220-grit sandpaper.
Change to 320-grit sandpaper, and sand the area again. Repeat with 400-grit and then 600-grit paper.
Apply the buffing compound to a soft cloth, and rub the area to buff until the surface matches the rest of the tub.