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Rust is a known problem on any knife in the kitchen, which requires maintenance and a prevention strategy. Some methods for rust prevention are better than others, and we will present the best-proven methods to keep your kitchen knives rust-free!
Proven methods to prevent rust on kitchen knives include:
- Don’t wash your knife in a dishwasher.
- Do not let your knife air-dry after washing.
- Don’t soak your knife in water.
- Clean immediately after use.
- Allow a patina to develop.
- Oil your knives periodically with food-grade mineral oil.
Rust on your kitchen knives will be a bigger or a lesser problem depending on where you live and how you treat your knives, but at some point, you will be faced with a rust problem. If your kitchen knives show signs of rust, try our proven rust prevention strategies and methods to clean any rust off your kitchen knives!
Do Kitchen Knives Rust?
Rust is corrosive oxidation that affects steel of any kind to differing degrees and normally begins in the presence of oxygen and moisture.
Contrary to popular belief, all steel will rust, even stainless steel, which is not rust-proof but rather rust-resistant. Stainless steel will develop rust if not maintained properly, but the oxidation process will take much longer than on other steel such as carbon steel.
Consequently, no steel knife in our kitchen is immune to the effect of this blight, and knife owners need to take precautionary steps to protect their knives from conditions that promote rust development. This may be easier said than executed, especially in harsh conditions prevalent in most kitchens.
The only kitchen knives not affected by rust are ceramic knives and knives with titanium blades. These knives do not have iron as part of the makeup of the blade and will not rust.
How Does Rust Develop On Kitchen Knives
Kitchen knives are a great tool to get food prep done, but the environment the knives are subjected to in the kitchen is not healthy for the steel.
To understand why this is, we need to look at what conditions promote the development of rust to take steps to protect our kitchen knives as best we can.
The factors that promote the onset of rust are as follows:
- Moisture. Water is one of the main factors promoting the development of rust on steel. This can be liquid water, water vapor in the air creating high humidity conditions, or steam.
- Oxygen. This gas is present in the air all around us. Even the moisture the knife comes into contact with contains oxygen, one of the catalysts for rust development.
- Salt. High salt levels, such as in the air at the coast or where salt is used, can speed up the rusting process of steel and cause the corrosion to spread rapidly.
- Heat. Heat is not one of the requirements for rust to occur, but it speeds up the oxidation process once it has begun.
As we can see from the conditions needed for rust to occur and conditions that accelerate the process, rust is not an issue we can escape, especially in the kitchen.
The kitchen environment is a boiling pot of rust-producing conditions on steroids! Kitchens are hot due to the stoves, ovens, and other heat sources used to cook food.
Steam or water vapor is a common ingredient in the atmosphere of a kitchen. Salt is a frequent seasoning used in food preparation, and of course, oxygen is in the air all around us!
This harsh kitchen environment creates the perfect storm of conditions to promote the development of rust on our kitchen knives.
Is Rust On Knives Dangerous
A question frequently raised regarding rust on knives, particularly kitchen knives, is whether the rust poses any form of danger.
Small rust spots on a kitchen knife are unlikely to pose any health risks for food preparation or contaminate the food with particles of rust. However, larger rust areas on your kitchen knives may be a different story altogether.
Rust causes pitting of the knife steel, which creates small indentations in the knife blade’s surface. These pits on the steel surface can harbor bacteria that may not be completely cleaned out when the knife is washed.
If the rust is well progressed on a knife blade, the rust can begin to flake off the steel. The rust particles can contaminate the processed ingredients and find their way into the final dish.
While rust is not particularly toxic to humans, particles of rust in a dish can detract from the texture and final quality of the food. While this may not be of too much concern in a home kitchen, professional kitchens would not tolerate this risk of compromising their food.
Patina Is Not Rust
Carbon steel knives will develop another form of oxidation called patina, which is not harmful to the steel. In fact, patina development on carbon steel knives protects the steel from harmful rust.
Patina is a dark, stain-like discoloration of the steel in contrast to the reddish color of rust. This oxidation normally occurs in the presence of weak acids, such as is present in tomatoes and lemon juice.
The patina oxidation is not corrosive and forms a protective layer on the steel’s surface, preventing moisture and oxygen from combining to form rust on the knife blade.
TIP: Keeping your knives sharper for longer is not only convenient but can also help to extend the life of your knives. Check out simple but clever tips in the article below:
5 Simple & Proven Tips: Keeping Your Knives Sharp Longer
How To Clean (Remove) Rust From Kitchen Knives
Removing rust from a knife blade is not as difficult as you may imagine, and you may be able to get it done with ingredients you already have in your kitchen!
The concept behind removing rust is a weak acid solution to break down the rust on the steel and clean it off the surface. This effectively halts the progress of the rust, and the knife can then be treated to prevent rust from recurring.
Pretty much any weak acid will do the trick to remove rust, but we have some ideas for you that will easily clean the rust off your kitchen knives.
Use Lemon Juice To Clean Rust From Knives
Lemon juice is a good source of weak acid to remove rust from a knife, and it is an ingredient common in many kitchens.
The process of cleaning rust off a kitchen knife with lemon juice is not complicated. The first step is to ensure the knife is clean. Rinse the blade in warm soapy water and dry it off before starting the rust removal.
- Cut a lemon in half. Cutting the lemon in half exposes the juice and gives a convenient way to hold the lemon.
- Rub the lemon on the rust spots. Run the cut side of the lemon over the rust spots on the blade.
- Add salt for stubborn spots. If there are some stubborn rust spots, dip the cut side of the lemon in some coarse salt and then rub the lemon over the rust spot. The salt acts as a mild abrasive, helping to dislodge the rust.
- Wash and rinse the knife. After removing the rust, wash the knife in warm soapy water, rinse with clean water and thoroughly dry the knife with a clean cloth.
TIP: A sharp knife makes all the effort out of making the cut, but not all knives can hold a sharp edge and stay sharp for a long time. Find out the best edge-holding knives in the article below:
These 3 Kitchen Knives Hold the Best Edge (You Should Try)
How To Use A Potato To Remove Rust From A Kitchen Knife
Another method to remove rust using produce from the kitchen is using a potato. This is not my favorite method, simply because it takes longer to get the job done than the other methods we cover.
You are also limited to the size of the rust problem you can address by the size of the potato.
- Push the knife into the potato. Push the knife into the potato until the blade’s rust spot is inside the potato.
- Leave for 2 to 3 hours. Leave the knife in the potato for between 2 and 3 hours to give the oxalic acid enough time to work.
- Remove from the potato and wash. Remove the knife from the potato and thoroughly wash and dry the knife.
This method is not the greatest because of the time the knife must be left in the potato. Leaving exposed knives on the kitchen counter is not the safest of practices. While this method works, we recommend using one of the other faster methods for rust removal.
Vinegar To Remove Rust From A Knife
Vinegar is also a useful rust remover for kitchen knives. The best vinegar to use is white spirit vinegar since it has the right acid strength for the task.
Stand the knife blade down in a glass with enough vinegar in the glass to cover the blade. Do not let the knife handle stand in the vinegar as it may damage the handle material.
Let the knife stand in the vinegar for 15 to 20 minutes. Remove the knife from the vinegar and gently scrub with fine steel wool or a kitchen sponge with a scourer on one side.
If the knife only has small rust spots, it is unnecessary to soak it in vinegar. Dab some white spirit vinegar on a paper towel and rub the vinegar into the rust spot. Gently scrub the spot with a kitchen sponge to remove the vinegar and the rust.
After a vinegar treatment, it is important to wash the knife to remove all the vinegar and thoroughly dry it before storage.
Baking Soda To Remove Rust on A Kitchen Knife
Baking soda is another kitchen ingredient that works well for rust removal on a knife. The slightly abrasive quality of the baking powder works well to remove rust spots.
Mix some baking powder with a small amount of water to form a thick paste. Smear the baking soda paste over the rust spots. Gently scrub the blade with a kitchen sponge. An old toothbrush also works well. Scrub in a circular motion over the rust spots.
Rinse the knife off after scrubbing and wash with warm soapy water. Dry the knife properly to ensure all moisture is removed.
TIP: Rust damage can weaken the structural integrity of the steel and permanently damage your expensive Japanese knife. Find out the complete guide that helps you in the article below:
Removing Rust From A Japanese Knife In 5 Steps (+ Prevention)
How To Prevent Rust On Kitchen Knives
Regarding kitchen knives, rust prevention is preferable to addressing rust that has already developed.
A knife that has been subjected to rust will have a surface marred by oxidation, which makes the steel susceptible to the re-formation of rust in the imperfections in the steel’s surface. Consequently, it is wise to take care of your knives from the outset to prevent rust formation.
There are some do’s and don’ts regarding knife care to prevent rust on your kitchen knives. We will start with some situations and actions you should avoid subjecting your knife to and then move on to action steps to prevent rust.
1. Do Not Wash Your Knife In A Dishwasher
A dishwasher is a convenient and timesaving kitchen appliance, but it wreaks havoc on knives. Dirty dishes can be cleaned in a dishwasher without a problem, but you should never wash your knives in this appliance.
Dishwashers use high water pressure combined with heat, salt, and abrasive detergents to clean dishes and utensils. This harsh environment in the dishwasher can make the rust problem even worse, and it can damage the cutting edge and handle of the knife.
It is always preferable to wash your knives by hand. This process does not take long and will prevent rust from forming on the blade if the knife is properly dried after washing.
TIP: Dishwashers are a great modern convenience that helps to eliminate some of the tiresome household chores like washing dishes, but they are not great for all forms of cutlery. Find out more in the article below:
Guide: Why Dishwashers Ruin Knives & What Knives Are Safe
2. Do Not Leave Your Knife To Dry On The Drying Rack
As we have seen from our discussions on the cause of rust, moisture and oxygen are key ingredients for the formation of rust.
Washing a kitchen knife and leaving it on the drying rack to air-dry exposes the steel to rust-forming conditions.
Always dry your kitchen knives with a clean cloth after washing to remove moisture and reduce the risk of rust forming on the blade.
3. Don’t Let Knives Soak In Water
If the knife has been used for a particularly messy or sticky job, you may be tempted to soak the knife in water to help dissolve the mess on the knife.
This is not a good idea, particularly with carbon steel knives. The extended exposure to water will result in rust forming very quickly on the steel.
Rather use warm soapy water and a kitchen sponge to clean the stubborn dirt from the blade. A sponge with a scourer on one side can also be used, but take care not to apply excessive pressure; otherwise, you can scratch the steel.
4. Always clean Your Knives After Use
After a busy evening of cooking and preparing a meal, you may be tempted to leave the dishes, including your knives, in the kitchen sink and wash them the next day.
This is a recipe for rust developing on your knives. The moisture from the food you processed with your knife will remain on the steel for an extended period, giving rust a chance to gain a foothold on the steel.
5. Allow a Patina To Develop On Cabon Steel Knives
Many people are not aware of the benefit of patina on carbon steel knives. When the steel begins to discolor, they view it as staining which must be removed.
Many knife owners scrub the patina or the “perceived stain” off with a scourer or steel wool to restore the knife to shiny steel.
Patina will help prevent rust formation, and it gives the blade character. Rather leave the patina on the blade to act as a protective layer.
TIP: Is patina a good thing or a bad thing on a knife, and should you force a patina or take steps to prevent it? Check out the detailed explanation in the article below:
Patina On A Knife: Prevent Or Force It? In-Depth Explanation
6. Oil Your Kitchen Knives
All kitchen knives can benefit from periodic oiling to coat the blade and protect it from rust. While it is not as important for stainless steel knives, there is nothing wrong with giving stainless steel the same periodic treatment.
Not just any oil will do, especially for knives used in food preparation. The best oil to use on your kitchen knives is food-grade mineral oil. Do not coat the knife with not too much oil, as this can attract dirt and dust, causing it to stick to the knife blade.
Do not use vegetable oil to oil your kitchen knives, especially if you will be storing the knife for some time. Vegetable oil turns rancid after a while and becomes a thick paste, creating a sticky, smelly mess on your knife that is difficult to clean.
This is the best way to oil your kitchen knives.
- Wash and dry the knife. The knife must be clean and dry; you do not want to trap any food particles or moisture under the layer of oil. This will defeat the object of protecting the knife from rust.
- Dab oil on a paper towel. Dab some mineral oil onto a kitchen paper towel.
- Wipe a layer of oil on the knife blade. Wipe the paper towel with the oil across the entire length of the blade. Only a thin layer of oil is necessary.
That is the simple process of adding a thin layer of oil to help protect your kitchen knives from rust. It is unnecessary to oil your knives every day, but oiling carbon steel knives once a week until they develop a patina will go a long way towards rust prevention.
Once the patina has developed, an oiling every 3 weeks should be sufficient. While stainless steel is less susceptible to developing rust, you can also give these knives a coating at the same time for added protection.
BTW: If you want to know more about Japanese and other knives and their sharpening, check out the books listed above. These books are recommended by professional sharpeners and knife makers (Amazon links):
- Japanese Kitchen Knives: Essential Techniques and Recipes
- The Knifenerd Guide to Japanese Knives
- Knife: The Culture, Craft, and Cult of the Cook’s Knife
- Sharp: The Definitive Introduction to Knives, Sharpening, and Cutting Techniques, with Recipes from Great Chefs
Kitchen knives are hardworking knives subject to conditions that are conducive to rust formation. It is important to apply the necessary steps to prevent rust from occurring on these knives to ensure you get the maximum use out of them and prevent issues with the food you prepare.
Rust prevention is better than dealing with the problem once it has started. Rust left unchecked can damage knives, and some kitchen knives can be expensive to replace. Establish a rust-prevention regime for your knives to keep them in top shape!
TIP: Part of knife maintenance is keeping the blade in good condition and free from corrosion (rusting). Check out the two best oils for kitchen knives maintenance in the article below:
These Are The 2 Best Oils For Kitchen Knives (+ How to Use)