Modern bathtubs are often made of fibreglass or acrylic, but they used to be primarily cast iron. The vintage look of a cast-iron tub can add appeal to your bathroom decor. Instead of replacing the old tub, make the most of its charm by giving it a makeover. Cast-iron tubs have a porcelain enamel coating that improves the colour and texture of the metal underneath. Re-enamelling the tub will enhance the look while still maintaining the antique appeal. The process of re-enamelling takes time and effort, but the shine should be worth it.
Pry off any caulk between the tub and wall or floors with a putty knife. Some cast-iron tubs are free-standing, so there may not be any caulk around the tub.
Grasp the drain cover with your fingers and turn it counterclockwise until it comes off.
Apply a heavy layer of masking tape around all fixtures on the tub to protect them.
Wash the surface of the tub down with a floor wax stripper, then a citric acid cleanser to remove the stripper. When cleaning, cover both the inside and outside of the tub.
Rinse the tub with water to remove residue from the cleaning products.
Wipe the tub with a clean towel. Apply denatured alcohol to a clean rag and wipe the both the inside and outside of tub.
Fill in chips or scratches on the tub surface with fibreglass putty. Follow the instructions on the product for proper application and drying time. Sand down the putty, once cured, with sandpaper so it is flush with the tub surface. If necessary, apply polyester glazing putty to over the fibreglass product to fill tiny indentations or pockmarks. Sand the second layer of putty once it cures. Wipe the tub to remove residue from the sanding.
Cover the tub surface with a bonding agent appropriate for acrylic urethane enamel. Follow the instructions on the product for proper application. Often you can apply the bonding agent with a clean cloth.
Spray on three coats of acrylic urethane enamel with a spray gun. Let the enamel dry between applications.
Sand off any bumps in the enamel with wet sandpaper and wipe the tub surface with a paper towel to remove the dust.
Buff the tub surface with a power buffer and auto polishing compound. Use the foam pad attachment on the buffer. This will fill in tiny scratches in the new enamel coating.
Cover the enamel surface with a polymer glaze car wax. Buff the wax over the enamel with a soft, clean cloth.
Take proper precautions to avoid inhaling the paint fumes. This may include an air mask and proper ventilation. Read the safety instructions on the enamel product.