How to Get Rust Off a Knife: 5 Methods That Actually Work
By Scott Bradley•24 years professional kitchen experience
I'll be honest with you: in 24 years of professional kitchen work, I've never had rust on my personal knives. Not once. That's not bragging. It's the result of habits I learned the hard way watching other cooks ruin good blades through neglect.
But I've seen plenty of rusty knives come through professional kitchens. The prep cook who left his knife in the sink overnight. The new hire who stored a wet blade in a leather sheath. The home cook who brings in their grandmother's carbon steel knife, orange with oxidation, asking if it can be saved.
The answer is almost always yes. Here's how to fix it, and more importantly, how to make sure it never happens again.
Why Knives Rust (And Why Mine Don't)
Rust is iron oxide. What happens when iron in steel reacts with oxygen and moisture. Carbon steel knives are especially vulnerable because they have higher iron content and lack the chromium that makes stainless steel resistant to corrosion.
But even stainless steel knives can rust. I've seen it happen with knives left in sinks, stored wet, or exposed to acidic foods without proper cleaning.
In professional kitchens, there's a simple rule: your knife never touches the sink. You use it, you wipe it, you put it away. Years of that habit means I don't think about rust prevention anymore. I just do it automatically.
The cooks who got rust? They were the ones who'd prep tomatoes, toss the knife in the bus tub, and deal with it later. 'Later' is how rust happens.
Method 1: White Vinegar Soak
White vinegar is the go-to solution for moderate rust. The acetic acid dissolves iron oxide without being aggressive enough to damage the underlying steel.
What You Need
- White vinegar (not apple cider or balsamic — you want the plain stuff)
- A glass or plastic container tall enough to submerge the blade
- Soft sponge or cloth
- Dish soap
- Dry towel
The Process
Pour enough white vinegar into your container to cover the blade. If your knife has a wooden handle, keep the handle out of the liquid. Vinegar will damage wood.
For light rust, 15-30 minutes is enough. For heavier oxidation, you may need several hours. I've heard of people going overnight, but check it periodically. You don't want to etch the metal.
Once the rust has loosened, scrub gently with a soft sponge. The rust should lift off without much pressure. If you're fighting it, soak longer.
Rinse thoroughly with water, wash with dish soap to neutralize any remaining acid, and dry immediately. I mean immediately, not 'in a minute,' not 'after I finish this.' Now.
Pro Tip
Never exceed 24 hours of vinegar exposure. Extended soaking can etch the blade surface and affect the finish. If 24 hours doesn't work, you need a more aggressive method.
Method 2: Baking Soda Paste
Baking soda is gentler than vinegar and works well for light surface rust or knives with delicate finishes. It's my recommendation for a first attempt on a knife you care about.
What You Need
- Baking soda
- Water
- Soft cloth or old toothbrush
- Dish soap
- Dry towel
The Process
Mix baking soda with just enough water to make a thick paste, about the consistency of toothpaste. You want it to stick to the blade without dripping.
Apply the paste generously over all the rusted areas. Let it sit for at least an hour. Two hours is better for stubborn spots.
Using a soft cloth, work the paste into the rust with gentle circular motions. An old toothbrush works well for getting into the area near the spine or heel.
Avoid steel wool or abrasive pads. Yes, they'd remove rust faster. They'd also scratch your blade, and those scratches become future rust initiation points.
Rinse with warm water, wash with dish soap, dry completely.
Method 3: Lemon and Salt
This method combines citric acid with salt's mild abrasive action. It smells better than vinegar and works well for visible surface rust.
What You Need
- Fresh lemon (bottled juice works but fresh is more effective)
- Coarse salt (kosher or sea salt)
- Soft sponge
- Dish soap
- Dry towel
The Process
Cover the rusted areas with a generous layer of coarse salt. Squeeze lemon juice over the salt until it's saturated. You'll see a slight fizzing as the acid reacts.
Let it sit for about two hours. Be careful with carbon steel, the citric acid can cause discoloration if left too long.
Scrub with the lemon rind itself or a soft sponge, working in the direction of the steel's grain.
Rinse, wash with soap, dry immediately.
Word of Caution
Citric acid is more aggressive than acetic acid. If you're working on a knife with a polished finish or reactive patina you want to preserve, stick with baking soda.
Method 4: Bar Keeper's Friend
When household remedies aren't cutting it, Bar Keeper's Friend is the next step. It contains oxalic acid, which is particularly effective on rust stains.
This is what I'd use if someone handed me a neglected knife and said 'fix this.' It's not the gentlest option, but it works.
The Process
Sprinkle Bar Keeper's Friend powder on the rusted areas. Add just enough water to form a paste.
Let it sit for 1-2 minutes, not longer. This stuff is more aggressive than the previous methods.
Scrub gently with a soft sponge, rinse thoroughly, wash with dish soap, and dry completely.
You may need to repeat for heavily rusted blades, but one application handles most cases.
Method 5: Rust Eraser (For Serious Cases)
If you're dealing with stubborn rust on a high-quality knife, a rust eraser is worth the investment. These are rubber blocks impregnated with silicon carbide, essentially a very fine abrasive designed specifically for blade maintenance.
Japanese knife shops sell these, and they're common among knife enthusiasts for a reason: they work without damaging the blade when used correctly.
The Process
Soak the rust eraser in water for about five minutes.
Cover the cutting edge with a towel for safety. You're going to be rubbing near sharp steel.
Gently rub the rust eraser over the affected areas, working in the direction of the blade's grain, usually lengthwise.
Use light pressure. You're removing rust, not metal. Let the abrasive do the work.
Wipe clean with a dry cloth. Follow up with a thin layer of camellia oil (tsubaki oil) or food-grade mineral oil.
When to Use This
Rust erasers are ideal for carbon steel Japanese knives, expensive chef's knives, or any blade where you want precise control over the rust removal process. They're overkill for a $30 beater knife.
How to Prevent Rust (The Actual Solution)
Here's the thing: rust removal works, but prevention is easier. I've used the same knives for over a decade without a single rust spot. The secret isn't complicated.
The Non-Negotiable Rules
- Wash and dry immediately after use. Not 'soon.' Not 'when I'm done prepping.' Immediately. This single habit prevents 90% of rust problems.
- Never put knives in the sink. The sink is where knives go to die. They sit in water, get bumped by other dishes, and start rusting before you remember they're there.
- Never put knives in the dishwasher. The heat, moisture, and harsh detergents are brutal on blades. Hand wash only.
- Dry completely before storage. Run a dry towel along both sides of the blade and the spine. Moisture hiding near the handle is how rust starts.
- Store in a dry environment. Knife blocks, magnetic strips, or blade guards all work. A drawer full of loose utensils doesn't.
For Carbon Steel Knives
Carbon steel requires extra attention. After drying, apply a thin layer of food-grade mineral oil or camellia oil before storage. This creates a barrier against ambient moisture.
Some cooks force a patina on their carbon steel to protect against rust. The patina (controlled oxidation) actually helps prevent the uncontrolled oxidation you don't want.
The Restaurant Habit
In professional kitchens, I kept a dry side towel specifically for my knife. Cut, wipe, continue. Cut, wipe, continue. After years of this habit, it became automatic.
You don't need a professional kitchen to build this habit. You just need to do it consistently until it stops feeling like extra work.
When a Knife Can't Be Saved
Most rusty knives can be restored. But some are too far gone.
If rust has caused deep pitting, actual holes or craters in the steel, the blade's structural integrity is compromised. You can remove the surface rust, but those pits will harbor moisture and bacteria no matter how well you clean.
If the rust has spread to the edge and caused significant metal loss, the knife may not hold an edge properly anymore.
If it's a cheap knife that's been neglected for years, your time is probably worth more than the restoration effort. Sometimes the right answer is to replace it and take better care of the next one.
For expensive or sentimental knives with serious damage, consider a professional blade restoration service. They have equipment and expertise that home methods can't match.
About Scott Bradley
Professional Chef • 24 Years Professional Kitchen Experience
Professional chef with 24 years of restaurant experience including Pizzaiolo at Purple Café, Kitchen Manager at Mellow Mushroom, and line positions at Feierabend, Il Pizzaiolo, and Paragary's. A.A.S. Culinary Arts from Seattle Central College, B.S. Business Administration from University of Montana. Every product tested through real professional kitchen use or extensive long-term home testing.
Read more about my testing methodology →