Enamel Cast Iron Bathtub Refinishing

Old porcelain tubs--clawfoot and other styles--are actually cast-iron tubs with a porcelain overlay. When the porcelain gets old, worn and discolored, you have to decide whether to replace it or refinish it. Tub refinishing is usually left to professionals because of the dangerous chemicals involved, but with the proper preparation, you can do it yourself and make the project that much more affordable. Talk to your tub refinishing supplier about getting the proper safety equipment.

Prepare Your Tub

Remove the drain hardware, the metal cover over the overflow hole, and any other hardware on the tub. Cut away all caulk from around the tub by the wall and floor. Scrub the tub very well with abrasive cleanser. Get it very clean and very dry. Then use duct tape or other plastic tape to hang plastic tarping on the walls and floors around the tub, sealing it alongside the tub edge. If there are external parts of the cast iron that aren't covered in porcelain, tape those off as well.

Acid-Etch the Surface

Put on your respirator, goggles, rubber gloves and long-sleeve shirt. Open a window or door and put a fan in it. Apply your etching solution (generally, hydrofluoric acid) with a brush, covering the entire porcelain surface of the tub. The acid shouldn't react with the plastic that's covering your walls and floor, but be cautious about spatters and spills anyway. Allow the etching solution to sit on the porcelain for 15 minutes. Sprinkle baking soda over the solution to stop the reaction, then rinse the tub thoroughly and let it dry.

Refinish the Surface

Put your respirator back on and fill your paint sprayer with epoxy primer made for porcelain. The primer is generally dark in color so you can see where you've already sprayed it on the white tub. Spray a very light coat, keeping the sprayer moving so there are no drips. Let the first coat dry for half an hour, then apply a second primer coat. Apply your topcoat of porcelain paint in the same manner, using from four to six coats. Let the paint set for two days before reinstalling the drain and fixtures and using the tub.