How to Remove Black Marks from a Porcelain Sink

Although you’re not sure who did it or how it got there, one morning you go to use your porcelain sink and you’re greeted to a big black mark. Oh no! How do you get rid of this mark ASAP?

Follow these steps for removing black marks from a porcelain sink:

  • Combine lemon juice and borax, let the mixture sit, and after 10 minutes, scrub your sink until the black mark is gone
  • Pour warm water and ammonia into a container, dip a sponge into the mixture, and use it to rub the mark away
  • Apply distilled white vinegar on the black mark for at least 10 minutes, then clean the sink

Ahead, we’ll go step by step and elaborate on how to use borax, ammonia, or distilled white vinegar to get your porcelain sink looking spotless again. We’ll even discuss what those black marks may be and share some tips for keeping your sink clean in the future. You’re not going to want to miss it!

Step-by-Step Processes for Removing Black Marks from Your Porcelain Sink

A large, long black mark on your white porcelain sink is definitely going to stand out. You might try rubbing the mark directly off the porcelain, but this doesn’t really do anything. You don’t want to bust out the heavy-duty chemicals, so what are your options?

You can rely on three common household products that should work hardily to remove black marks from your porcelain sink. These are borax, ammonia, and distilled white vinegar.

Using Borax

Borax is a chemical compound that goes by names like disodium tetraborate, sodium tetraborate, and sodium borate. It looks a lot like baking soda, although it’s not edible. This white powdery substance is instead used to kill ants and other insects, fight off mildew and mold, and remove stains.

If you don’t have borax handy, you can find it here on Amazon.

Here are the steps to follow to clear away those unappealing black marks on your porcelain sink with borax.

Step 1: In a bowl, pour out a cup of borax and combine it with 1/4th a cup of lemon juice. Mix the ingredients together.

Step 2: If your sink isn’t already perfectly clean (outside of the black mark, of course), then do that next. Use dish soap and a soft sponge to clean the sink. Make sure the sink is completely dry before you proceed.

Step 3: Your lemon juice and borax should have made a paste after you mixed them. Take this paste now and spread it across the length of your sink’s black mark. Give the paste at least 10 minutes to work into the stain.

Step 4: With a gentle sponge, remove the lemon juice and borax residue, cleaning your sink thoroughly until no traces of the paste remain. Towel-dry the sink and you should see that the black marks are gone. If not, repeat the process again.

Using Ammonia

If you don’t have borax handy, then we’re sure there’s some ammonia in your kitchen cabinets or pantries. This hydrogen and nitrogen compound is an ingredient found in a lot of heavy-duty kitchen and bathroom cleaners. That’s because ammonia is adept at removing stains from wine and cooking grease as well as disintegrating vegetable oils, animal fats, and grime.

Is your panty empty and you don’t have ammonia? Buy a two-pack here on Amazon.

Get your ammonia ready and then follow these steps for a beautiful, streak-free porcelain sink.

Step 1: Again, start with a clean sink if you don’t already have one.

Step 2: In a bowl or cup, pour a gallon of warm water and then add one tablespoon of ammonia.

Step 3: Next, dip your soft sponge into the ammonia/water mixture and begin rubbing hard. You should see the black marks coming up as you do this.

Step 4: Remove all residue of the ammonia.

Using Distilled White Vinegar

Your third option for cleaning black marks off your porcelain sink is to use distilled white vinegar. This is a different product than the standard vinegar you may already have in your home. Distilled white vinegar has a grain alcohol base that receives oxygen during production. When this happens, acetic acid develops, as do bacteria.

You can find distilled white vinegar here on Amazon.

Distilled white vinegar is edible, as it helps foods to pickle, but more often than not, you’ll rely on this type of vinegar for cleaning. Here’s how.

Step 1: Ensure your porcelain sink is clean and dry before you begin.

Step 2: Pour a tablespoon or two of distilled white vinegar into a spray bottle. Make sure it’s undiluted so it works at max strength. Then, spritz the black streaks on your sink with the vinegar.

Step 3: After 10 minutes or more pass, grab a soft sponge and begin vigorously cleaning the area. Then, clear away any residue with water and let the sink dry completely.

Step 4: If needed, repeat the process until the black marks are completely gone.

What Causes Black Marks on Porcelain Sinks?

Now that you’ve patched up your porcelain sinks so they’re white and shiny once more, you want to get to the bottom of what caused the black marks in the first place. Here are some culprits to look out for.

Aluminum Utensils and Pots

If your porcelain sink is in the kitchen, then the most likely reason the sink has black streaks is because of your aluminum cookware. Pots and pans as well as utensils made of aluminum can scuff up your sink. All it takes is someone in your family casually tossing aluminum cookware into the sink and the cookware scraping up against the sides or bottom of your sink and you have black marks.

Food Stains

In some instances, those dark marks could come from certain food stains. Tea bags and coffee grounds especially will leave black streaks in your porcelain sink, so don’t let these foods linger for too long.

Hard Water

Is your water soft or hard? It’s important to know. Soft water is considered a surface water that doesn’t have magnesium and calcium ions as well as other minerals. It’s a natural water that comes from river basins and rainfall.

Hard water has a higher quantity of dissolved magnesium and calcium. This water will pass through gypsum, chalk, or limestone before reaching you, allowing the buildup of minerals to develop.

Hard water could stain your porcelain sink and do a number on the water pipes as your fixtures have a buildup of minerals. 

Soap Scum

Soap scum is another problem. Also referred to as lime soap, soap scum includes alkali metals like magnesium stearate and calcium stearate as well as fatty acids. When you use hard water and soap in your bathroom or kitchen, soap scum will soon form, leading to stains on your porcelain sink.

Since soap scum is not water-soluble, it’s not as easy as rinsing your sink to remove it. Excess soap scum can get backlogged in your pipes and invite bacteria into your sink as well.

Tips for Keeping Your Porcelain Sink Pristine

You put a lot of elbow grease into removing the black marks from your porcelain sink, and you don’t want to do it again anytime soon if you can help it. The following handy tips will maintain your sink’s pretty condition.

Use a Dish Drainer or a Dish Mat

If it’s cookware like pots, pans, and utensils made of aluminum that have scuffed up your porcelain sink in the past, you want to avoid any direct aluminum-to-sink contact in the future. Buy a dish drainer or a dish mat made of soft material and put it in the sink. Encourage the rest of your family to use the dish drainer or mat every time they deposit items in the sink.

Alternately, you can buy non-aluminum cookware.

Don’t Leave Food in the Sink Long

When you and your family are done enjoying a meal together, don’t let the dirty dishes with food residue sit. Instead, rinse them off and, if you can, take some time to do the dishes post-meal. A dishwasher really comes in handy here.

Even if you don’t have time to get to the dishes right away, rinsing away food residue–especially coffee grounds­–should keep your sink looking brand new.

Use a Water Filter

If you suspect hard water is your problem, then we’d suggest testing your water first. If your water is 0 to 60 milligrams per liter of calcium carbonate, then it’s soft. Water that’s between 61 and 120 mg/L is somewhat hard, and the hardest water is over 180 mg/L.

Sink water filters can remove the minerals from your water so your porcelain sink never bears the brunt of your water quality again.

Skip the Bar Soap

By using a water filter and switching from bar soap to liquid soap in your bathroom, you can prevent soap scum from forming, which will also do your sink and your plumbing fixtures a big favor.


Your porcelain sink may be marred by black marks from soap scum, hard water, food stains, or aluminum cookware. By using ammonia, distilled white vinegar, or borax, you can tackle these marks and clear them from your sink once and for all. Best of luck!

George Sab is a retired home improvement professional. For over 30 years, he has educated his clients and helped them make the best choice for their homes. George started A Great Sink in 2017 to share his knowledge with the world and assist his readers on their journey to their perfect home!


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