Uncover the 4 Easy Steps to Refinishing an Old Cast Iron Sink for a Smooth and Durable Finish

This is how to refinish a cast iron sink and here I am showing my old high back, rusty, and very dirty farm sink that I resurfaced using these diy bathroom sink makeover steps to use in my modern farmhouse bathroom makeover.

Refinish an Old Cast Iron Sink DIY

So, you want to refinish a cast iron sink but you’re thinking DIY bathroom sink project may be a bit out of your league?

Think again!

I’m so glad you found me because I refinished a high-back farmhouse sink using these exact steps and had spectacular results. That is after a little trial and error…

To save you some time and trouble (because this project was not without issues) I want to share what did and did not work!

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Just a friendly reminder: This tutorial and any opinions or recommendations are genuinely mine, but this is not a substitute for consulting a professional. I also use affiliate links to earn a commission.

Refinishing an Old Farmhouse Bathroom Sink Step-by-Step

showing a dirty old cast iron sink and the steps to refinish a cast iron sink - before and after

Did I mention that this diy project saved me over $300? I paid $120 for my sink, $120 in gas to pick it up (more on that story later; it was quite the distance!), plus the cleaning and refinishing supplies needed for this diy bathroom sink. So, depending on what you pay for your cast iron sink, you could save even more!  

Vintage cast iron sink repair sounds intimidating, I agree. But the steps to refinishing an old cast iron sink are so simple. Yes, this project was not without frustration, but it was not hard!

Listen, if you can scrub sand and paint, you can refinish a cast iron sink. Follow these steps to create a diy bathroom sink using an old farmhouse cast iron sink:

Step 1: Cleaning Cast Iron

dirty old cast iron high back sink

My old cast iron sink was filthy. I couldn’t have picked a dirtier sink if I tried. Hopefully, yours is not as bad! But hey, if I can get this cast iron sink clean, then anything less dirty should be a breeze.

I first started by using some good old Dawn dish soap and water. Using the green side of a sponge and a whole lot of elbow grease, have at it.

You should rinse and repeat until removing all of the entire dirt layer.

Next, Bar Keeper’s Friend is your friend! This stuff is amazing. I used the original powered type; however, one of my Instagram followers suggested the foam may work faster and with fewer applications. 

This is how to refinish a cast iron sink and here I am showing the bar keepers friend, with my high back cast iron sink in the background, that I used as one of the cleaning tools for this diy bathroom sink makeover.

Either way, start by sprinkling a layer of Bar Keepers Friend onto your sink, then get it a little wet to make a paste, and then, once again, scrub.

Rise and repeat, and repeat, and repeat.

I lost track of how many times I reapplied. Just keep scrubbing!

partially cleaned old cast iron sink

Step 2: Sanding Cast Iron Sink

Next is sanding your cast iron sink. Sounds weird, right? Something about roughing up this farmhouse sink made me hesitate.

Although this old sink had certainly seen better days, I still didn’t want to make it look any worse than it already was. But, what is it they say, things have to get worse before they get better?! 

Proper grit for sanding the porcelain enamel on cast iron is quite high, light 400. But I didn’t have this on hand, and wasn’t about to make another trip to the hardware store. So, I decided to go with the highest grit sandpaper I had, which was 220.

I suggest getting the 400 grit sandpaper before hand and using this. And definitely do not use anything lower than 220!

You won’t see a whole lot after sanding, but skipping this step leads to poor bonding and a less durable finish. Because the original cast iron finish is so smooth, the enamel may not grip without roughing things up a bit by sanding.

Step 3: Repairing Cast Iron Sink Enamel

If your sink has larger chips or blemishes, now is the time to repair them.

I was lucky enough to have found a sink that was essentially blemish free. Or at least it had ones that were not large enough for me to patch.

I have more on the steps to repairing cast iron later in the post so keep reading!

Step 4: Refinishing Cast Iron Enamel

refinished cast iron sink using high gloss rust-oleum enamel spray paint

The last step in this process is fixing the topcoat, which I went with a urethane primer and high gloss spray enamel.

Choosing the right enamel paint and determining if I needed to first prime was the hardest part of this entire process!

Lucky for you, I’ve done the research and am sharing the results. But geez! There were many options and conflicting opinions on which products were best. After weeks of over-analysis paralysis, I ended up priming my sink, followed by using Rust-Oleum Enamel.

Funny story about how I ended up using Enamel, because I specially wrote down and was told by my dad to use Epoxy. For now, I’ll skip the story telling and stick to the steps, but I’ll share this at the end, so keep reading if you want a little laugh.

Whichever product you end up using, I HIGHLY recommend using the spray vs brush version. This stuff is tacky and very finicky to work with so unless you like the look of brush strokes, go with a spray option.

** Coming soon! Don’t miss my feedback on how this product holds up. Opt-in my newsletter here!

Priming Porcelain Enamel Cast Iron

Depending on what you’re using to refinish your cast iron sink, you may or may not need a primer. I chose to go ahead and use this Urethane primer.

Why? Because, first, I preach about the proper steps for painting, which always include priming with a good primer. And it just didn’t seem right to me to not apply one.

Second, my sink had lots of tiny imperfections in the bowl; and this primer helped level those. 

I used a paint brush to apply the primer and I believe this was my biggest mistake because you can see the brush strokes. No matter how much I sanded and coated over this, they will not go away.

If I were to do this all over again, I would stick to spray products. Nothing that requires brushing or rolling.

Update: I’m annoyed by the brush marks from the primer I used so as soon as it’s warm enough out (currently the snowflakes are flying), I’m going to start back at square one, and this time use Rust-Oleum (spray) Filler Primer.

Coming Spring of 2024!

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Re-enameling (aka Painting) a Cast Iron Sink

You first need to remember; this is not regular paint; it’s finicky. So, get out your patient pants because you’ll need them! 

For absolute best results, getting a smooth finish the first time around is most ideal. Because wet sanding and re-coating is a beast.

It’s not completely impossible, so don’t freak if you have drips or blemishes. It’s just way more work when you have to fix these and re-coat.

But don’t worry, I had to do it three times, so I have a few tricks to getting a smoother surface!

Enamel Spray Paint Tips

  • Don’t get excited and keep applying layers. Speaking from experience, if you apply too many thin layers, you will end up with drips. Once it’s covered, walk away! You can always go back and do another round after it dries.
  • Check the temperature outside. Again, speaking from experience, I went ahead and tried to spray when it was 51 degrees outside and wound up with a huge mess. You can see the bubbled/cracked enamel in the wet sanding section of this post.) The directions say the lowest temperature is 50, but I had terrible results at 51.
  • Be mindful of where you are spraying. For example, the first time the plastic which I used to protect the bottom portion from getting painted, flew up in a gust of wind and landed in my tacky paint.
  • If you are working outside avoid a windy day for two reasons; the wind makes it harder to get even coverage where you want it. Also, things like leaves and grass like to blow in the wind. And I ended up with a few blades of grass once again in my tacky paint.

Here is what happened to my sink after the wind put plastic into wet enamel:

blemish on a cast iron sink in wet enamel paint

Wet Sanding to Fix Blemishes in Enamel Paint

If you notice imperfections, bubbles, or dust particles in the dried enamel, and you want a smooth surface, you’ll need to wet sand before applying any additional coats of enamel.

Here you’ll see on the left what my bubbled/cracked enamel looked like and on the right, you’ll see what it looked like after wet sanding:

bubbled enamel on a cast iron sink
wet sanded enamel on a cast iron sink

Starting with a sheet of 400 grit sandpaper, I cut the sheet in half and wrapped it around an old sanding block.

Then, I dipped this setup in a bowel of water before moving on to sanding. I also sprayed the sink’s surface with water from a spray bottle.

Next, I sanded the problem spots just like I would any other sanding project. Working away at the blemishes until I was happy with how smooth it was.

Lastly, repeat the process with 600 grit sandpaper. Making sure to keep the sandpaper and sink’s surface wet while doing so.

Tip: Ace and Agway sell these high grit sandpapers and they also sell it by the sheet so you don’t have to waste money on an entire pack!

Once you’re done sanding, wipe away any sanding dust and ensure the surface is clean before applying the next enamel paint coat.

Painting the Base of a Cast Iron Farmhouse Sink

dirty and cracked paint on the bottom of an old cast iron sink

I applied black spray paint after cleaning the sink and scraping and sanding the surface. Looking back, maybe I should have used an etching primer, which chemically roughs up the metal to improve adhesion. But I didn’t. 

My hope is because I did such a thorough job sanding the metal before applying the spray paint, things should be good. Keep ya posted on how this holds up!

Here is what my sink base looked like after I sanded:

sanded base of a cast iron sink

If you don’t sand the surface, I’d recommend looking more into an etching primer to give the paint something to hold onto. 

Initially, I went with flat black Rust-Oleum spray paint, but this showed every little imperfection, so I applied a final layer of gloss black spray paint and am totally in love with the results!

Can you believe I don’t have any pics of how good the bottom turned out?! I need to fix that…

Repairing Chipped Cast Iron

Another way to freshen up your cast iron sink is to repair any damages using a high-quality epoxy-based filler designed for cast iron repairs. One well-known product is the J-B Weld Water Weld Epoxy Putty. This epoxy putty is suitable for cast iron repairs.

Another option is the Homax Porcelain Chip Fix. This product repairs porcelain and enamel surfaces. What I like about this product is that it comes in a small bottle with a brush applicator, making it easy to use for touch-up repairs.

Lastly, the Rust-Oleum Tub and Tile Repair Kit, while primarily intended for bathtubs and tiles, can work on a cast iron sink. I’m a big fan of Rust-Oleum’s other products, so I feel this is a trustworthy option for repairing cast iron damage.

When choosing a product, make sure it is compatible with a cast iron enamel surface. Additionally, consider the size and extent of the repair to determine which product best meets your sink’s needs.

Epoxy Vs. Enamel to Refinish Cast Iron

I went back and forth about using Appliance Epoxy or Rust-Oleum Enamel paint. I literally made three different trips to the hardware store, buying and returning, and then re-buying what I started with. 

Appliance epoxy is a strong, moisture-resistant enamel that offers an ultra-hard, washable surface.

Enamel is an oil-based product that is designed to create a hard and durable surface.

Not a helpful differentiator, right?! Now you can probably understand why I went back and forth so many times. Because they both sounds like they will work. But which is best?!

My dad educated me that epoxy is much stronger than enamel. He explained it that epoxy is like a glue, and enamel is a coating. I don’t know if that helps you, but it my mind I envisioned the epoxy sticking and the enamel peeling off in one giant piece.

I had used the Rust-Oleum Appliance Epoxy paint before in my camper remodel, and it held up just fine, so between his explanation and my past experience, the decision was made. Appliance epoxy it is! I even made myself a note in my phone that said, “use epoxy”.

But what do you think happened? I used the enamel.

I realized my mistake when we were chatting over dinner, and I said how easy the enamel was to apply. The rest of the conversation went something like this:

Dad: I thought you were going to use epoxy.

Me: No, you said to use the enamel (whipped out my phone to show him the note) See, you said to use… Oh… whoops!

After having used the enamel, I did not want to risk the epoxy not adhering well to the enamel, so I stuck with the enamel for the remaining coats. Time will tell how well this holds up!

Which is better?

The debate of which product is BEST is not over! The Appliance Epoxy says it is an enamel, so is there really any difference between this and the Enamel I used??!

I have reached out to Rust-Oleum to get their input on the difference between these two products and which is best for Cast Iron. Stay tuned!

Update: The reply was this: “Our Rust-Oleum Specialty Appliance Epoxy is a one part epoxy meaning it is very similar to an enamel in performance with the differences being in the formulation of the paint. However, we would not recommend using this paint for a sink as the full water immersion can cause the paint to blister and peel.”

Humm, welp! From the sounds of it, neither the Appliance Epoxy nor the Enamel are (in Rust-Oleum’s opinion) good for refinishing cast iron.

Based on this, I’m happy I went with the Enamel because it really is so much easier to use than the Appliance Epoxy.

Refinishing Cast Iron Sinks FAQs and Helpful Tips

You can resurface a cast iron sink by following the above steps. Each step plays a crucial role in preparing the surface for a finish that your paint adheres well to.

Skipping or rushing through the steps can lead to less-than-ideal results and potentially cause unnecessary frustration.

Here are the two articles I found most useful when determining how I would refinish my old cast iron sink:

Cleaning Rusted Cast Iron

You’ll want to address any rusted spots on your cast iron sink, which takes a specialized cleaning product. Also, rust is like pesky weeds in your garden; once it starts, it’ll keep growing unless you do something about it.

I used CLR to address the rust spots on my cast iron sink. Even if you don’t have any signs of rust (yay!), you should still use this stuff to remove any other build-up on your sink’s surface. It removes the things you can’t see, like calcium and lime.

Like any other paint project, your effort in prep is never a waste of time. Skipping this step can lead to poor adhesion and a bumpy finish because the resurfacing enamel can’t stick to a dirty surface.

Helpful Cleaning Tools

To speed up the cleaning process, add these helpful scrubbing tools to your next Walmart online order:

I switched between all of these to prevent myself from getting fatigued.

What is the Coating on a Cast Iron Sink?

The coating on a cast iron sink is porcelain enamel. This shiny white layer is visually appealing and protects the sink from rust. In addition, this layer provides a smooth and easy-to-clean surface. 

I learned this through my researching primer and paint because I needed to know what I was dealing with to better understand how to get a durable finish.

Finding a High Back Cast Iron Sink

Or any old farmhouse cast iron sink, actually. First, check your local ReSource, ReStore, and salvage shops. You might get lucky and find exactly what you need. This was not the case for me.

This is how to refinish a cast iron sink and here I am showing my old high back, rusty, and very dirty farm sink that I resurfaced using these diy bathroom sink makeover steps to use in my modern farmhouse bathroom makeover.

Next, head to Facebook Marketplace and try the following search terms:

  • cast iron sink
  • high back cast iron sink
  • farmhouse sink
  • old/vintage/antique sink
  • white sink
  • etc.

Depending on where you live, you may need to set your search radius quite wide. 

Design Details to Look For

The high-back cast iron sink I set my sights on was much harder to find because, if you notice, the faucet comes out of the high back, not from the base.

Oh, and I had a tight space to work with in my bathroom, so this old sink had to be no larger than 36. Which, this smaller size is rarer since the most common old farmhouse sinks are double the length because they have a sideboard or drying area attached.

These are some of the design details to look for in a high back sink:

  • faucet placement
  • lack of skirting so you can see the colored base
  • overall size (check the bottom for the size, it should be stamped on there!)
  • number of faucets

I’ll be the first to admit I’m picky, but guess what? This attention to detail is exactly how I seamlessly mix old and new using affordable thrift store finds and end up with a beautifully curated, stylish home.

How I Paid Only $120 for My High Back Sink

Believe it or not, I drove 11 hours round trip for this old cast iron sink!

Call me crazy, but my boyfriend went along with this slightly ridiculous idea (so I think that actually makes him the crazy one), and we took the opportunity to turn this into a mini-adventure!

My high-back cast iron sink cost more in gas than the actual sink.

Listen, when a “new” cast iron sink, replicating an old one, costs somewhere in the $600 range, the long drive didn’t seem so nutty. I decided I had nothing to lose and would refinish a cast iron sink instead of buying a new one. 

In the end, this sink still cost me less than half of what it would to buy this new. Life is about the journey; I’m just living my best frugal life!

I’ll have after pics coming soon. The bathroom this is going into is currently being renovated, and I’ll share all the pretty after pictures as soon as it’s ready!

Taking the time to refinish an old cast iron sink is sure to totally transform your bathroom into the modern farmhouse space that you’ve always wants. And all on a budget while building your DIY skills!

So, now that you know the steps to refinish a cast iron sink, what are you waiting for?!

Hey Friend!

project planner pack

Every successful DIY project starts with a plan. That’s why I created the Project Planner Pack.

It’s everything you need to complete your project on time and on budget.

Unleash your creativity with a click, download your Planner Pack and start your DIY journey today!

furniture flipping // diy projects // home renovations // modern farmhouse decorating ideas