How to Restore a Cast Iron Tub

Before the days of molded fiberglass, bathtubs were generally made of cast iron frames covered (or partly covered) in porcelain. If you've got an old clawfoot, built-in or other cast iron tub on which the porcelain has become dingy, dull and in need of restoration, there are numerous businesses that specialize in this. You can also do it yourself. It's an advanced project that requires specialized materials and dangerous chemicals, and you shouldn't attempt it unless you've had some experience at other types of restoration projects.

Things You'll Need

• Plastic tarp
• Masking tape
• Respirator
• Rubber gloves
• Goggles
• Full-coverage protective clothing
• Acid etching paste
• Brush
• Paint sprayer
• Porcelain primer
• Enamel paint for porcelain (a paint-polyurethane combination)

Instructions

1. Remove all fixtures from the tub. Tape off all surrounding areas with plastic tarp and tape. Also tape off any part of the tub that isn't coated in porcelain (i.e., any bare-iron exterior parts of the tub).

2. Put on your protective clothing, goggles, respirator and gloves. Apply acid etching paste to every part of the porcelain surface of the tub. Give it about 15 minutes to eat away the exterior shine of the existing porcelain, making to dull and flat. Rinse thoroughly. Dry the tub.

3. Continuing to wear your protective gear, use the paint sprayer to apply a coat of porcelain primer to the tub. The primer should be dark in color so you can see where it's already been applied. Make sure you cover the tub completely with a thin, even layer with no drips or streaks. Let the primer dry for 30 minutes to an hour.

4. Apply your first coat of enamel porcelain paint in the same manner, with your paint sprayer, keeping the layer very thin and even. Cover the surface completely, avoiding any streaks or drips.

5. Allow the first coat of enamel paint to dry for 30 minutes to an hour. Apply subsequent coats in the same manner. Apply from four to six coats, keeping each of them very thin and smooth. Let the final coat cure for at least two days before re-installing the fixtures and using the tub.

Tips & Warnings

• The etching acid is extremely dangerous. Don't leave it unattended in the tub.

References

• ThisOldHouse.com: How to Refinish a Cast-Iron Tub.