Cast iron tubs are extremely durable. They are coated with a porcelain enamel that is applied to the bathtub using high heat. This coating is not easily scratched and is acid resistant, though not completely acid proof. Many methods can be used to remove paint from your cast iron tub. The best method to choose is dependent on whether the paint is a splatter inside the tub, or if the paint to be removed is the decorative coating on the exterior of the tub.
Determine if the paint to be removed is on the inside or outside surface of the bathtub.
Scrape the paint off the interior of the tub, gently, using the razor blade scraper.
Spray Goof Off on any remaining paint stains and let sit for a few minutes.
Wipe the area to be cleaned with a clean rag.
Wash the bathtub as usual with the bathroom cleaner.
Put a dust sheet around the tub to protect the floor when removing paint from the outside of the tub.
Use a paint stripper to remove any paint on the outside of the tub. Follow the package directions carefully.
Paint stripper can be painful if you get it on your skin. Gloves are recommended. If the paint stripper you have chosen is not working, there are commercial grade strippers that can be found at auto parts stores. When using paint strippers, be sure to ventilate your workspace well.