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Rust is a nuisance anywhere in the household, but there's something particularly annoying about finding it on kitchenware, say, a set of knives. While rusting is a natural process likely to occur when using metal knives, it's preventable. But what do you do if rust has already formed?
There are numerous products for cleaning rusted kitchen knives, including natural cleaners such as vinegar, baking soda, and lemon juice. If these don't get the job done, you can use store-bought rust-removal chemicals to clean more stubborn rust stains on your knife blades.
This article will serve as your guide to removing rust from your kitchen knives and preventing it from forming in the first place. You'll also learn the differences in how the two most popular knife blade materials rust and which between the two is best suited for you.
Your kitchen knives are rusting because the iron in the blade steel comes into contact with water and oxygen. Iron and oxygen are attracted to each other like magnets. When the two elements combine in a chemical reaction called oxidation, ferric oxide—often called rust—forms.
Given that oxygen is abundant in the atmosphere and knives are constantly wet from washing, the knife blades are prone to rust without proper care. Rust causes metal to decay, and if not dealt with quickly, the affected metal will get weaker and eventually fall apart.
With the elements that lead to rusting ever-present in the kitchen, how come not everyone's kitchenware gets rusty? Could how you're handling your knives and other utensils be predisposing them to rust?
Here are some bad habits that might be causing your knives to rust:
Common substances found in your household and kitchen can make rusting worse. These include salt, acids (e.g., acetic acid and citric acid), and chemicals such as bleach. Temperature changes can also worsen rusting.
There are two general categories of steel: stainless and carbon.Â
Carbon steel predominantly comprises iron with a small percentage of carbon and other metals. Stainless steel also primarily contains iron, at least 10.5% chromium, carbon, and a few other metals.
The chromium in stainless steel surrounds the iron and protects it from oxidation. However, chromium reduces the blade's durability, which leads to an increased frequency of sharpening.
Stainless steel kitchen knives can rust. Although stainless steel is more resistant to rust than carbon steel due to the chromium alloyed into the metal, it's still not rust-proof.Â
If the passive chromium oxide layer that acts as a protective barrier against oxidation is compromised, you may notice specks of rust on the knife blade. The thin layer works by preventing the iron in the alloy from reacting with water and oxygen in the atmosphere and forming iron oxide.
In addition to the formation of rust, small holes or pits can also develop deep in the metal structure. This is a localized and more damaging form of corrosion known as pitting corrosion. It occurs when the chromium oxide layer on the steel is physically or chemically damaged, exposing the steel underneath to corrosive environments.
Your choice of blade material will depend on the kind of cook you are. Serious cooks typically prefer carbon steel knives because they have sharper edges that make slicing, dicing, and chopping more effortless.
If you live in a coastal or high-humidity area, stainless steel knives are best as carbon steel rusts quickly in these climates.
Let's explore the pros and cons of carbon steel and stainless steel knives.
The elements needed to initiate the chemical reaction that leads to rusting are all present in your kitchen. Fortunately, you can save rusted blades and restore them to their former glory using items also readily available in your kitchen or store bought products.
If you have any of the items below in your kitchen, you can remove rust from your kitchen knives:
But wait a minute—didn't I say in a previous section that acids and salts can worsen rusting? How then can they also help get rid of rust?
If you recall, I also mentioned that rust causes metal to decay. But since the surface of the metal corrodes first, you can use these substances to break down the rusted parts and then wipe them off to reveal the unaffected metal underneath.Â
It's a lot like exfoliation. You scrub off the old cells to reveal the fresher, more youthful skin underneath.
Here's how to get rid of rust using the aforelisted kitchen ingredients.
Cleaning rust off your kitchen knives using a vinegar soak is pretty straightforward. It requires little effort since chemistry does all the hard work for you.
To use this method to get rid of rust, follow these steps:
For thin blades and light rust stains, you can use baking soda. So long as your knives don't look like they were salvaged from the Titanic, this should do the trick.
Here's how to go about it:
The abrasiveness of salt combined with the acidity of lemon juice makes for an effective rust buster. Some articles may recommend baking soda instead of salt, but this is counterproductive. Since baking soda is a weak base, it will neutralize the effect of the citric acid in the lemon juice.
To proceed with this technique, follow these steps:
Potatoes contain oxalic acid—an acid found in many household cleaning products. Oxalic acid dissolves rust, making potatoes a potentially powerful rust remover.Â
This method of rust cleaning involves the following steps:
This rust-removal technique involves simply soaking the knives in a citric acid cleaning solution. You can purchase citric acid, also referred to as sour salt, in your local grocery store, hardware store, or kitchenware store.
Follow these easy steps to try this straightforward technique:
The sulfenic acids present in onions make them effective rust removers. However, it's not a popular technique for cleaning rust owing to the pungent smell of onions and the painstaking process of running the blade through the onion until you see results.
If you want to try this method regardless, do this:
If there're still rust stains left on your kitchen knives after using one or more of the above natural rust removers, you can purchase rust removal products in your local hardware store to eliminate these tough stains.Â
Bear in mind that some of these chemicals can be toxic if not properly handled or used. So make sure to read the instructions and follow them strictly to avoid any unfortunate incidents.
Here are some chemical rust removers you can use if the homemade rust removers fail:
My number one recommendation for chemical rust removers is Metal Glo Polishing Paste. The product is certified safe for cutlery and cookware and is suitable for cleaning and polishing any metal surface—including carbon steel, gold, copper, and brass.Â
To use Metal Glo, follow these steps:
Whink Rust Stain Remover is a low-concentration hydrofluoric acid solution. It quickly and easily removes heavy rust, but you can also use it to clean rust stains off various household surfaces, such as soft furnishings, carpets, and bathroom fixtures.
However, since Whink Rust Stain Remover is an acid-based rust removal product, you should not use it on anything too delicate.Â
Here's how to use the rust remover:
Bar Keepers Friend Powdered Cleanser is an all-purpose household cleaner that's suitable for use on almost any metal surface. It's made with oxalic acid, the same compound found in potatoes, but in concentrated form. Consequently, it's effortless to use, requiring minimal effort to achieve the desired results.
Follow the steps below to use the rust-removal agent correctly:
Depending on how tough the rust is to remove, repeat this as many times as necessary to remove the rust from your knives and get them looking good as new.Â
Another great way to get rid of rust on your kitchen knives is to use rust erasers. A rust eraser is a tool made from a special compound designed to remove rust from knives and other stainless steel and carbon steel surfaces. They resemble the school erasers you likely used back in your school days and are ideal for routine maintenance of your kitchen knives.Â
I recommend Rust Eraser - Single from Amazon.com. It removes rust and other surface blemishes on metal and gives your knife blades a brushed satin finish. To use the rust eraser:
Some rust erasers might require you to soak them first for a few minutes before using them.
Now let's discuss the pros and cons of rust erasers.
Once you get the rust off your kitchen knives using the aforementioned rust-removal techniques, it now becomes a matter of keeping the rust off. So how exactly do you keep your kitchenware rust-free? Glad you asked.
Here are 3 Ps to remember about rust prevention:
How many times have you tossed a knife into the drawer or slid it into the knife holder without thoroughly drying it? Too many to count? I've been guilty of this too. We somehow convince ourselves that the blades will eventually dry, so what's the big deal?
Sure, they will dry. But the time the moisture sits on the blade's surface is enough for the chemical reaction that causes rust to begin.
Try to remember water is the main culprit of rusting. So after cleaning and rinsing your knives and other metal utensils, always ensure to dry them before storing them. Otherwise, your kitchenware will be at risk of developing rust spots.
Overall, proper cleaning of your knives should consist of three steps, not two: wash, rinse, and dry.Â
If you dry your knives thoroughly before putting them away, then place them somewhere damp, oxidation will still occur, and rust will start forming on the blades. So make sure your storage cabinets and knife blocks are as dry as you can get them.
When you notice more than one or two utensils start to get rust spots, despite storing them well-dried, inspect your storage spaces. They may be damp and will likely result in more of your kitchen utensils becoming rusty.
While you’re at it, check the state of utensils you hardly use and have stored away. Are they rusted or still in pristine condition? If the former, more will likely follow suit if the storage area remains corrosive-friendly.
Applying mineral oil to your knives and other metalware in the kitchen can help prevent rust. But doesn’t oil pack moisture onto the knife blades, you ask?Â
Oil creates a protective layer on the blade’s surface, which reduces direct contact with water and air.Â
Don't wait until the rust spreads to get rid of it. As soon as you notice rust spots or stains on your knife, try one of the homemade rust removers suggested in this guide to clean the rust off.Â
Delaying action may cause rusting to penetrate deeper into the metal, which will reduce the chances of natural rust-removal techniques becoming successful.
You should get rid of your rusty kitchen knife when rust damage is extensive and does not seem to improve after trying various rust-removal techniques. Rusted kitchenware can contaminate your food, causing health problems. So ensure to remove all the rust before using the utensil in question.
Ceramic and titanium kitchen knives do not rust. Unlike the popular carbon steel or stainless steel knives, ceramic and titanium blades do not contain iron, which is one of the three chemical elements required for rust to form. No iron, no rust.
There are myths surrounding rust that I want to address as I wrap up. These myths have permeated our thinking, leading to incorrect assumptions about rust and what causes it to form.Â
First up on the chopping block: stainless steel doesn't rust.Â
False. Stainless steel isn't impervious to rust. When exposed to corrosive environments for extended periods, the protective layer of chromium oxide may get damaged, making rusting possible.
Next up on the chopping block: rust can cause tetanus.Â
Tetanus is caused by a bacteria called Clostridium tetani. Getting cut by your rusty kitchen knife isn't going to cause tetanus. However, any damage to the skin, whether caused by a rusty object or not, allows the tetanus-causing bacteria to enter your body.
Nobody likes unsightly rust stains on anything in the house, least of all on kitchen items that come in contact with food. If your kitchen knives are rusty, you can help restore them such that they look new again using items in your kitchen or store-bought products.
After successfully removing the rust from the blades, ensure to always dry them well after cleaning and store them in a cool, dry place henceforth to prevent rust.
