How To Clean a Porcelain Bathtub or Sink

Cast-iron bathtubs and sinks were a common fixture in older homes, yet their unique vintage charm means we're seeing them pop up in many newer remodels. Unfortunately, years of use or neglect can make for one discolored and dingy tub or sink! Here are a few tips to keep the porcelain on your antique fixture looking next to new.

What You Need

• Liquid dishwashing soap
• Ammonia
• Baking Soda
• Lemon oil
• Table salt
• Lemon
• Old rag
• Nylon or soft sponge
• Bucket


1. Cast-iron is traditionally covered with a porcelain enamel that's fused to cast-iron in a furnace. While porcelain is a highly durable surface, it's susceptible to chips, cracking and dulling of the finish. If you use the wrong products, you will accelerate the degradation of the surface, so let's begin by talking about what not to use. Abrasive cleaners such as scouring powders, white vinegar (or other cleaners with a high acidic content), and steel wool should all be avoided, as they can damage the finish. For the best results, always start with the gentlest cleaner and work your way up to more powerful applications. Remember, proper care will simplify ongoing maintenance.

2. For gentle weekly cleaning, mix 2 tablespoons of dishwashing soap containing a grease cutting agent with 1 gallon of hot water. Use a soft rag or sponge to dip into the soap mixture and scrub the tub or sink. Rinse well.

3. For monthly or deep cleaning (when moving into a new home or cleaning up a newly purchased vintage tub or sink), pour warm water into a bucket and add 1/4 cup of baking soda and 1/4 cup of ammonia. While baking soda is slightly abrasive, it's mild and generally safe to use on porcelain, while ammonia cuts grease and soap scum buildup.

4. Soak a non-abrasive sponge in the baking soda/ammonia solution. Scrub the surface of your porcelain bathtub or sink, paying particular attention to stained areas.

5. Dip the sponge in the solution, scrub and repeat until you're satisfied.

6. Rinse well.

7. After rinsing, wipe thoroughly with a clean rag or the baking soda will leave a white film behind.

8. As a last resort, mainly for tough-to-remove rust stains, cover the stain with table salt. Take half of a lemon and squeeze the juice over the salt. (I have also heard cream of tartar and lemon juice works, but have never tried it). Scrub the salt/lemon mixture with a clean cloth or a nylon sponge. If the stain still doesn't come up, leave the paste-mixture on the stain for an hour or so. Squeeze more lemon juice on the stain and try scrubbing the stain again, then rinse and wipe clean.

9. To add shine and a protective coating, squeeze a small amount of lemon oil onto a clean rag and rub the lemon oil into the sides of the porcelain bathtub or sink, avoiding the bottom of the tub to prevent slipping. The lemon oil will help repel soap scum and other dirt to keep the sink/tub clean longer, and it smells good, too!

10. If none of these suggestions work and your tub or sink still looks a bit lackluster, it might be worth the investment to have your fixture re-glazed by a professional. While there are DIY re-glazing kits on the market, the results are usually shoddy and do not last. Unlike fiberglass or acrylic, your cast-iron fixture can stand the test of time, so it's well worth the expense to hire a specialist for the job. Keep in mind, this doesn't run cheap. I was quoted around $500. While if properly cared for, it should last for many years, the finish will not be as durable as the original porcelain finish. Re-glazing, done in your home by a professional, is not a duplication of the tub's original porcelain dip-coat, but actually a specially formulated gloss paint. In some cases, you can send a valuable cast iron tub off-site for a new dip-coat, but this is usually extremely pricey.

Additional Notes:

  • Bathtub rings can usually be blamed on oily bath products or a clogged drain. If you use a bath oil product, make sure to do a quick cleaning afterward and keep the drain clog-free.
  • It's always wise to test a small hidden section first to ensure that the cleaner will not cause any adverse effects to the surface of the porcelain.

(Images: Kimberly Watson)