How To Clean High Carbon Steel Knife

Finding rust stains on any of your cookware may seem like the end of the utensil's use. However, this isn't always the case.

So, how can you remove rust from a carbon steel knife? There are numerous methods used to remove rust from utensils. These methods include; scrubbing with baking soda, soaking in vinegar, sticking it into a potato, sawing the knife into an onion, plunging the knife into the dirt, and many more.

Learning how to remove rust from a carbon steel knife doesn't have to be an expensive affair. With these methods, you only use items that are readily available in your kitchen.

Back to Basics

Before exploring these methods and outlining the procedures, let's first understand what we are dealing with.

What is Rust and How Does it Form?

Scientifically known as hydrated iron (III) oxide, rust is a reddish-orange flaky layer that usually appears on some metals.

Rust is formed due to the oxidation of iron and forms when certain metal gets into contact with water for long periods. The iron reacts with oxygen and water to form hydrated iron (III) oxide.

Here is the word equation for the reaction:

iron + water + oxygen → hydrated iron (III) oxide

Water doesn't necessarily have to be present for the reaction to take place. The presence of water in the air that may settle on the metal also results in rusting.

Why Do Knives Rust?

Iron is a secret element found in the steel used to make knife blades. Combining these three elements, oxygen, iron, and water, will result in rust formation. So, when you expose your knife to water for long periods, the blade will rust.

But what if your blade is made of stainless steel? Unfortunately, stainless steel is only stain-resistant, not stain-proof. Research shows that stainless steel features 10.5% of chromium by mass, an element that isn't susceptible to oxidation. However, under certain conditions, stainless steel will rust, although not as severely or quickly as conventional steel. When exposed to saline, damaging chemicals, grease, heat, or moisture for long periods, stainless steel corrodes. However, depending on the stainless steel quality, your knife may be less or more resistant to rusting.

Unlike stainless steel, whose probability of rusting is quite low, carbon steel, which contains no corrosion-resistant elements, can rust if it's left in a moist area for a long time—rust forms due to the presence of oxidizable iron in carbon steel's alloy.

At What Rate Does Carbon Steel Rust?

How fast rust forms on your carbon steel knife blade will depend on many factors. Where the knife is stored or left is a major factor determining the speed at which rust forms. The presence of catalysts, humidity, weather, temperature, and other environmental factors of the knife's location will influence the speed at which rust forms on the carbon steel blade.

Six Methods You Can Use to Remove Rust from a Carbon Steel Knife

As mentioned above, there are numerous ways to remove rust from your carbon steel knife. Below, we have outlined the methods and their respective procedures.

1. Using Baking Soda

Baking soda is mainly used to remove light rust strains and works well on items made from thin metal.

To remove rust using baking soda:

First, thoroughly clean the blade of your knife to remove dirt. Avoid using water since it's is a primary element in rust formation. Instead, use a cleaning solution and wipe it down using a cloth.
Next, mix a little bit of water and baking soda to create a thick paste.
Spread the thick baking soda paste all over the blade, ensuring that all the rusty spots are well covered.
For light rust stains, apply the baking soda paste to a toothbrush and speed it across the knife blade.
For severe rust stains, let the paste sit on the blade for an hour or more, then use a wire brush, steel wool, or an abrasive sponge to scour the object and remove the rust.
Wipe the blade with a piece of cloth to remove the excess paste.
Apply some mineral oil to ensure that the blade is lubricated and protected from rust in future.

2. Using Vinegar

Is there any item that vinegar can't clean? For rust stains that don't go away, using white vinegar is the trick. White vinegar contains a substance known as acetic acid that will attack the rust. Other forms of vinegar may leave stains.

To clean your knife using vinegar:

First, thoroughly clean the blade of your knife to remove dirt.
Pour vinegar into a pan, bowl, or cup.
Place your knife's blade into the solution and let it soak for about five minutes. Letting it soak for longer may damage your blade.
For severe rust strains, remove the blade from the vinegar and scrub the rust off with an abrasive sponge, steel wool, or wire brush.
For lighter stains, wipe down the blade using a cloth.
Apply some mineral oil to ensure that the blade is lubricated and protected from rust in the future.

How to remove rust from carbon steel knives with Bar Keeper's Friend.

3. The Scouring Method

This method involves using either a scouring pad, a wire brush, steel wool, an abrasive sponge, or fine-grit sandpaper to remove rust from your knife's blade.

First, thoroughly clean the blade of your knife to remove dirt.
Scrub the rust stains on the blade using your scrubber until the stain is removed.
Wipe down the blade using a cloth
Apply some mineral oil to ensure that the blade is lubricated and protected from rust in future.

4. The Potato Method

Potatoes contain oxalic acid, a key ingredient found in many cleaning products. Oxalic acid dissolves rust. To clean your knife using the potato method:

First, thoroughly clean the blade of your knife to remove dirt.
Stick your blade's knife into the potato, making sure that all the rusty parts are fully concealed in the potato, and leave it for a few hours.
Remove the knife and wipe with a cloth.
Apply some mineral oil to ensure that the blade is lubricated and protected from rust in future.

5. The Onion Method

Onions contain sulfenic acid that helps to get rid of rust naturally. To clean your knife using onions:

First, thoroughly clean the blade of your knife to remove dirt.
Using your rusted blade, saw back and forth into the onion until the rust comes off.
Remove the knife and wipe it clean with a cloth.
Apply some mineral oil to ensure that the blade is lubricated and protected from rust in future.

6. The Dirt Method

Dirt can also be used to remove rust stains.

First, thoroughly clean the blade of your knife to remove dirt.
Plunge your blade into the soil a dozen times.
Remove the knife and wipe it clean with a cloth.
Apply some mineral oil to ensure that the blade is lubricated and protected from rust in future.

If all these methods fail to remove the rust, the ultimate solution is to buy a new knife.

FAQs

Does Rust Weaken My Knife's Blade? Yes. When rust is left unattended for long, your knife will lose some of its strength due to the decaying on the blade.
Does Removing Rust From My Knife Weaken It? This will greatly depend on the method you use. Using harsh chemicals, leaving the blade in vinegar for too long, or scrubbing too hard may damage your blade.
How Can I Prolong My Knife's Use? Sharpen it regularly, wash and dry it right after every use, wash it by hands, and use cutting boards at all times.
How Can I Prevent My Knife From Rusting? Dry your knife as soon as possible after every wash, avoid leaving it in the sink or dishwasher, and apply oil to prevent rust from forming
Carbon Steel or Stainless Steel? While stainless steel outshines carbon steel in the rusting department, carbon steel is easier to sharpen, stronger, and more durable due to its high carbon content.