How To Remove Rust From A Cast Iron Sink

Oh no! You accidentally dropped a heavy pot in your cast iron sink, and it left a big chip all the way down to expose the iron underneath! Despite your best intentions, you didn’t repair the sink right away, so now the exposed iron is coated in crusty, orange rust. So, now what?

While it might look like a nightmare, repairing that cast iron sink of yours isn’t overly complicated. First things first, though, you’ll need to remove the rust. Here’s how to do it. 

How Do you Remove Rust From An Iron Sink?

Although removing the flaking orange coating on your cast iron sink might seem daunting, it doesn’t have to be overly tricky. Generally, cast iron sinks are coated in a thick layer of enamel to protect the iron from rust, so the rust usually is isolated to a small portion of the sink. 

In some cases, you might be dealing with an old cast iron sink that has been overrun with rust for decades, so the task might take longer. However, before you get too overwhelmed, read through the following methods to see just how easy it is to remove rust from your cast iron sink. 

Sand It

If there’s a small amount of rust in the chipped area, you might be able to sand it away without an issue. Thicker rust might not lift as quickly, so you might need the help of a chemical, but it doesn’t hurt to try sanding it first. Here’s what you’ll need:

  • 000-grade sandpaper
  • Wire brush
  • Hand vacuum

Use 000-grade sandpaper for sanding the rusted area gently. Go over the area three to four times with the sandpaper to lift the rusty particles. Alternatively, use a wire brush to achieve the same sanding effect if the rusted area is in a hard-to-reach location. Be careful not to scuff areas around the rusty spot, though, as you might leave scratches in the sink’s finish. 

After you finish sanding, use a hand vacuum to remove the tiny rust particles. 

Food Grade Citric Acid

If sanding the rust doesn’t work, you might want to try food-grade citric acid. This stuff works wonders on rust stuck in small crevices or rusty spots that won’t lift. If you try this method, be sure to sand down as much as you can first. Here’s what you’ll need:

  • Food grade citric acid
  • Hot water
  • Old toothbrush
  • Soft cloth

Mix a tablespoon or so of citric acid with enough hot water to create a loose paste. Apply it to the rusty area, then give it a few minutes to work. Using an old toothbrush, gently scrub the rusty area to help lift the corrosion from the surface of the sink. You might need to use a bit of elbow grease to get the rust to lift, but avoid vigorously scrubbing, as you might accidentally damage the surrounding area of the sink. 

After the citric acid does its thing, use clean water and a soft cloth to wipe up the residue. Be sure to clean the area with water and wipe it dry to ensure new rust doesn’t form. 

Diluted White Vinegar

White vinegar is a miracle worker for many scenarios – you can use it for baking, cleaning, deodorizing, and much more. So, the fact that it works wonders on rusty sinks isn’t much of a surprise. Here’s what you’ll need:

  • White vinegar
  • Water
  • Spray bottle
  • Wire brush or old toothbrush
  • Soft cloths

Start by diluting vinegar in a spray bottle. Fill the bottle half full with white vinegar, then fill the bottle the rest of the way with water. Spray the rusted area generously with the vinegar solution and allow it to sit for about half an hour. 

After the time passes, use a wire brush or an old toothbrush to scrub the area. This will help lift stubborn rust particles still clinging to the sink’s surface. After you finish scrubbing, rinse the area thoroughly with clean water, then wipe it dry with a soft cloth. 

Can You Repair A Chipped Cast Iron Sink?

After you remove the rust from your cast iron sink, you need to repair the area. If you don’t, you’ll be back to square one in a few weeks after more rust forms. So, pick up a repair kit from your local hardware store and cover the chip with epoxy. 

A DIY epoxy repair might not look the best, so you can always seek the assistance of a professional to ensure a seamless appearance. However, if you’re not too worried about the aesthetics of the sink, you can easily fix it yourself. 

Here’s what you’ll need:

  • 400- to 600-grit “wet and dry” sandpaper
  • Sponge 
  • Mild dish soap
  • Bucket
  • Water 
  • Epoxy repair kit
  • Soft cloth

Clean It

Before you start, you need to clean the area and prepare it for epoxy. Fill a bucket partially with warm, soapy water. Next, use a soft sponge dipped in soapy water to clean the area. Avoid using abrasive scrubbers, as you could scratch the surrounding area of the sink.

After scrubbing the area, use a sheet of wet and dry sandpaper to sand the area and prepare it for epoxy. This will help rough up the surface so the epoxy will adhere better. Once you finish sanding, wipe away the sanding dust with a soft cloth. Let the area dry, then move on to the next step.  

Note: While you can use bleach to clean the area, we recommend sticking with a mild cleaning detergent diluted in water. In some cases, bleach can damage the sink’s surface, so we recommend avoiding it for cleaning your cast iron sink.

Apply Epoxy

Most cast iron sinks feature a thick enamel coating to help increase the sink’s durability and rust resistance. When this coating chips, it can expose the metal beneath, creating a spot for rust to take over. So, after you remove the rust, you need to repair the chip, and to do so, you’ll need an epoxy repair kit. 

You can find these kits at your local hardware store. Pick a color that matches the enamel coating on your cast iron sink. Once your sink is clean, mix the epoxy according to the manufacturer’s instructions. In some cases, you might have to wait a while before applying it, so be sure to follow the instructions to a tee. 

Once the mixture is ready, use a wooden toothpick or the applicator brush that comes with the kit to apply the mixture to the chip. If the chip is deep, you might have to apply the material in several coats, ensuring you allow adequate dry time between each coat. 

The manufacturer’s instructions should indicate the correct wait time. After you complete the repair, let the repair dry completely for 24 hours or as long as the label specifies. Avoid scrubbing the area for seven days following the repair.

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