How to Remove Rust from Knives: Baking Soda & More

Even with the best care, stainless steel and of course carbon steel knives can develop rust. This article will offer some guidance on properly caring for and removing rust from knives. There are several chemicals and tools that make rust removal easy. Read further to learn the best methods to remove rust step by step and what should be avoided.

What Causes Kitchen Knives to Rust?

Knives rust for a variety of reasons. The main cause is when a reactive steel comes in contact with an acidic substance. This can be something as simple as water but often comes from commonly used acidic ingredients like tomato and citrus. Rust, or iron oxide can form on steel when knives are not cleaned properly. When food is left on the blade of your knife, a chemical reaction can occur resulting in rust.  
Can you restore a rusty knife? Absolutely. Superficial rust and even more substantial damage can be repaired. Read on to learn how to restore a rusty knife as well as how to avoid rusty cutlery in the first place.

5 Methods to Remove Rust from Kitchen Knives

Method #1 - Removing Rust with Baking Soda

Baking soda, (sodium bicarbonate) is a common household ingredient that is useful for removing rust from a kitchen knife. Not only is the texture slightly abrasive, but it has a basic nature to neutralize acidic materials in rust.

• Step 1: Mix baking soda and a small amount of water into a bowl to create a thick paste. 
• Step 2: Apply the baking soda paste to the knife
• Step 3: Use a soft cloth to massage the rust spots. If that doesn’t work you can move on to a small brush, like a toothbrush and work the rust spot. Steel wool can cause deep scratches, so we recommend avoiding it to remove light rust.
• Step 4: Wipe the blade clean and wash with dish soap and dry well.

Method #2 - Removing Rust with Whetstone Rust Eraser

A rust eraser is a small tool made from combining rubber with knife sharpening compounds like silicone carbide. Rust erasers are great to have on hand because they are clean, easy to use and this method minimizes  damage to the knife blade. 

• Step 1: Soak rust eraser for 5 minutes
• Step 2: Use the rust eraser to clean rust by rubbing it over the affected sections of the knife blade. Scrub with the grain to remove rust stains.
• Step 3: Wet your block again if it dries out
• Step 4: Wipe the blade clean and wash with dish soap and dry well.

Additional Methods - Removing Rust with Alternative Natural Methods

Citric Acid

Another ingredient that you are likely to have around, a lemon is a great source of citric acid. This method is most effective when combined with the baking soda method. You can use a stand alone citric acid solution, make a paste with lemon juice or just rub the knife with a piece of lemon sprinkled with baking soda. Citric acid will eat away at the rust when combined with baking soda. 

Vegetables [The Potato Method]

Certain vegetables contain enough acid to help remove rust. Potatoes contain oxalic acid and onions contain sulphonic acid. Both substances when rubbed on rusted areas can help remove it.  

Vinegar

Simple white vinegar uses acetic acid to remove rust. Submerge your chef knife for  5-10 minutes and wipe down with a clean rag. Any remaining rust can come off with a rust eraser. 

Chemicals to Avoid

Online you might find recommendations for the chemical WD-40 or other items like mineral oil for cleaning and restoring cutlery and cookware.

We recommend not to use chemical cleaning solutions on tools you’re planning to cook with. It may be effective when removing rust from metal, but save it for items in your tool shed and not the kitchen.  

Proper Knife Maintenance to Keep Rust Away

Avoiding rust is easiest with high chromium stainless steel blades, but even carbon knives can be kept free of rust with if you follow some basic steps. Without fail, clean your knives with warm water, dish soap and a soft sponge, cloth or paper towel and dry immediately after using.

Especially for carbon steel knives, it’s a good idea to keep a damp cloth on hand and wipe down your blade periodically. This is especially important when cutting ingredients.

Learn more about Japanese knife care on our blog.

Conclusion 

Whether you buy a new knife or are adding to a knife set, be thoughtful in choosing the steel that best works with your kitchen style. Carbon knives are a great investment but require a bit more maintenance to keep them free of rust. If you find yourself with a rusted knife, a bit of elbow grease and one of the methods listed above can help restore your knife to great condition.