How To Remove Rust From A Knife

By Ryan Leavitt •  Updated: 03/17/21 •  6 min read

To effectively remove rust from a knife, soak the blades in a bowl of vinegar overnight. After they soak, get a steel brush and scrub off the rust until it’s clean. This method requires some effort but is highly effective in removing significant rust from a variety of items.

One of the worst things that can happen to a knife is rust.

Rust can occur because of a variety of reasons, and sometimes, it can be unavoidable.

Luckily, there are multiple different ways you can remove rust from a knife.

Some methods are designed for severe rusting, while others will work better for light corrosion.

Each requires some effort, but it will be worth it in the end.

In this article, we explain the different ways to remove rust from a knife.

So, if you need to clean out some rusty knives, you’ve come to the right place.

Read on to learn more.


Why Do Knives Rust?

Rust happens because of the oxidation of iron.

This happens when metals come into contact with water for too long.

This is caused by a mixture of oxygen and iron reacting to moisture and results in a reddish substance on the metal.

The substance is called iron oxide but is more commonly referred to as rust.

Your knife doesn’t even have to be submerged in water for this to happen, in fact, water in the air has been known to cause this reaction.

That’s why you shouldn’t leave or wash your knives in the dishwasher, because aside from the fact that the wash cycle can damage and dent the blades, leaving them wet for too long is usually the cause of rust, even with stainless steel blades.

The Proven Methods

If you have rust on your knives for whatever reason, there’s no reason to panic.

There are a couple of things you can do to remove the corrosion from the metal, which we’ll be diving into in this section.

Method #1: Using Baking Soda

This is one of the most popular and convenient methods out there since most households already have baking soda in their pantry.

To do this, you will first have to clean your knife.

It’s best to avoid water since that’s what caused the rust in the first place; instead, you can use a cleaning solution and a cloth to remove whatever dirt is on the blade.

Next, you have to mix a generous amount of baking soda with a bit of water or lemon juice to create a paste.

From there, apply the thick paste to the blade and scrub it with a toothbrush if the rust isn’t too heavy, but if you have a very rusty blade, you might have to use a non-abrasive sponge or steel wool.

After that, all you have to do is wipe the blade clean to remove all the excess paste, then put some mineral oil to lubricate the blade and protect it from rusting in the future.

Method #2: Giving Your Blades A Vinegar Bath

If you don’t have baking soda, this is a great alternative.

For this method, you need white vinegar, make sure to only use this type as other vinegar might leave stains on the blade.

White vinegar contains acetic acid which targets and attacks rust.

Simply pour some vinegar into a pot or pan and leave your rusty blade in there to soak.

Make sure to only leave it in for a maximum of 5 minutes as any longer, you might risk damaging the blade.

Once you’ve taken the blade out, all you have to do is wipe the blade.

This method is great for light rusting, but for heavier rusting, you might want to use the other methods on this list.

Method #3: WD-40

Next up is the WD-40 method, which has been known to work wonders on old, rusty blades.

First, you have to spray the blade and rusty areas with a generous spritz of WD-40.

From there, you have to use very light sandpaper, we recommend 400 grit, and gently sand the rust off the blade.

Be careful to not touch the edge as that can be dangerous and you also risk damaging the edge of your blade, affecting its sharpness.

After lightly sanding the blade, all you have to do is wipe off the excess WD-40, which should be enough to do it.

Keep in mind though, that this isn’t the most sanitary method and we do not recommend doing this with any knife you’ll be using for food prep.

Method #4: The Natural Methods

If you don’t have any of the above materials on-hand, then it might be time to look at some natural methods.

Take note though, that these aren’t the most effective ways to get rid of rust, but they do a decent job, considering none all of these materials are natural.

Using An Onion

Onions contain sulphonic acids that can help get rid of rust.

Simply saw your blade back and forth into the onion, and the acids will slowly get to work at removing the rust.

Using Dirt

Dirt is another great way to remove rust naturally.

Some people recommend sticking the blade into rich soil around a dozen times to get rid of rust.

This doesn’t work for everyone and it depends on the type of soil present in your area, so keep that in mind if you choose to try this method.

Using A Potato

This is one of the best natural remedies for a rusty knife.

This is because potatoes contain oxalic acid, which does a great job at removing rust.

To use this method, all you have to do is stick your rusty blade into a potato and leave it for a couple of hours.

From there, pull it out and then give it a good wipe with oil and that should get the job done.


If you’ve been staring at a rusty knife and feeling bad, it might be about time for you to try one of these methods.

All of them use simple items that most people have in their household, and if you don’t have them, you can always try the natural methods that use food and other natural resources.

The point is, there are a whole lot of ways people can get rid of rust on their knives using a variety of materials.

And if you really can’t get it out, then it might be best for you to get a new knife.

If you think one of these methods will work for you and your rusty blade, then it might be about time for you to try them yourself!

Ryan Leavitt

Hi my name is Ryan Leavitt a Marine Corps Veteran and currently an over the road trucker (Long Haul). I am no expert chef but am enjoying preparing my own meals on the road and testing all the different knives.