How to Clean a Cast Iron Tub

Co-authored by Michelle Driscoll, MPH

Last Updated: August 2, 2021 References

Cast iron bathtubs are a stylish and vintage addition to anyone's bathroom. Cast iron tubs are typically covered in a coat of porcelain enamel, which is fused to the cast iron itself. While cast iron is incredibly durable, the enamel coating it is typically prone to chips, scratches, and dulling over time. Luckily, if you use the correct cleaning products and use the right techniques, cleaning a cast iron tub can be easy.

Method 1

Method 1 of 3:

Soaking the Tub

1
Soak the tub in warm water and dish soap for 30 minutes. As your bathtub fills with warm water, add a couple of squirts of a mild dish washing liquid to it. Let the mixture bubble up and create suds. Once it's filled, let the solution soak for 30 minutes. Leave your tub filled up and let the soap solution break down soap scum and grime. ^{[1]
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- Choose a dishwashing liquid that has a grease cutting agent for the best results.
2
Drain and rinse the tub. Once you've allowed the solution to soak, you can remove the plug in the tub to drain it. Once all of the water is drained, use the faucet to fully rinse off any remaining soap from the surface of the tub.^{[2]
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- Saturate a clean sponge into warm water to rinse off hard to reach places.
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3
Dry down the tub with a non-abrasive cloth. Use a nonabrasive cloth such as a microfiber cloth to dry down the entirety of the bathtub. Make sure to get all the areas of the bathtub, or soap scum may be left behind.
- Do this once a week to keep a clean bathtub.

Method 2

Method 2 of 3:

Removing Soap Scum and Grime

1
Mix warm water, baking soda, and ammonia in a bucket. Fill up a five-gallon (18.92 l) bucket with warm water from your faucet. Then use a measuring cup and add 1/4 cup (45 g) of baking soda and 1/4 cup (45 g) of ammonia into the bucket.^{[3]
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- Wear gloves when handling ammonia or other harsh cleaners.
- Ammonia will remove soap scum while the baking soda will wash away grime without scratching or damaging your cast iron tub.
- Never mix bleach and ammonia together because it creates a toxic gas.^{[4]
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2
Dip a nonabrasive sponge in the solution and scrub the tub. Thoroughly saturate a nonabrasive sponge into the bucket and use it to scrub down the basin of the tub. Work the sponge in small circular motions until all of the grime and soap scum has been removed. Spend more time scrubbing especially dirty areas to fully clean them.^{[5]
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- Remember to use the solution on the fixtures of the tub, in addition, the tub's basin.
3
Rinse down your tub. Use the faucet or a shower head to rinse down the inside of your tub thoroughly. Remove all of the baking soda and ammonia solution that you just scrubbed into it.
- If you don't have a showerhead that reaches, you can empty out your bucket and fill it with water to rinse your tub.
4
Dry your tub. Use a lint-free cloth to thoroughly dry down your tub. Make sure that you lift up any remaining solution or it can leave a white film on your tub.
- This deeper cleaning method should be done once every month.
- Once the tub is dry, rub your hands along the sides and bottom of the tub, to check for remaining soap scum or grime. If you find any, scrub that part of the tub again. Then, rinse and dry it.

Method 3

Method 3 of 3:

Maintaining a Clean Tub

1
Rinse and dry down the interior of your tub after each use. It may seem like too much to rinse and dry down your tub, but it will prevent you from having to do deep cleanings often on it. Rinse down and dry your tub after every use to prevent soap scum buildup.
2
Do not use abrasive cleaners or cleaning materials. Acidic cleaners like scouring powders or white vinegar shouldn't be used on a porcelain enamel finish because it can discolor and damage it. In addition to the cleaner itself, refrain from using rough cleaning tools like steel wool because it can scratch your tub and ruin its finish.^{[6]
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3
Rub lemon oil into the bathtub. Rub pure essential lemon oil into a soft cotton cloth. Apply the lemon oil to the sides of your bathtub to prevent future soap scum buildup. You can purchase lemon oil online, or at stores that carry essential oils.^{[7]
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- Don't apply too much oil to the basin of your tub or it will be slippery.
4
Keep your drain clear and in good working order. A clogged drain means your tub is more likely to get soap scum build up or stuck-on grime. Check your drain often for blockages, and take quick action if your drain seems to have a clog.
- You might use a drain catch to collect hair and other debris during a shower. This can prevent a clog.