Why do Knives Rust & How to Prevent Knives from Rusting
By: Jack Mancuso
When you buy a cutlery set, you might not think about rusting. Nonetheless, one day you find specs of rust. No one wants to cut with that. The question remains why do knives rust, & how to prevent knives from rusting? Is there a remedy?
What is Rust?
Rust, also known as iron oxide, is a flaky red-orange substance you sometimes see on metal. It accumulates when the iron in a knife reacts to moisture. Note: that moisture can come from high humidity, too. It is a natural chemical reaction to which salt and acidic water can accentuate.
Why do Knives Rust?
Since your knives have metal in them, they’re susceptible to rust. Dishwashers increase the chance of rusting because the cutlery remains in the wash for longer than it does when you clean your pieces by hand.
Are my Knives Dishwasher Safe
When purchasing your cutler, check the manufacturer’s guidelines for care. It should say whether or not the knives are dishwasher safe. If there is no information, look to stainless steel, which is hardy and fairly resistant to rusting.
Shopping TIp: Some products have labeling with numbers such as 18/10. This indicates the amount of chrome and nickel in the pieces. The higher the number, the better quality of the knife. However, they can get pricey.
Many serious cooks won’t put their knives in the washer at all, even if they’re labeled dishwasher safe. Quick cleaning and drying preserve the blade longer. If you’re going to use the dishwasher, follow these simple guidelines to help deter rusting:
- Pre-rinse, preferably as soon as you are done with the knife.
- Measure detergent carefully. Excess can become abrasive
- Put your knife away as soon as the load is done
How to Prevent Knives from Rusting
Once you know why knives rust, the next obvious question is how to prevent it. When you invest in a good set of kitchen knives, you want them to last a long time. Some people become possessive and even nostalgic over one or two of their favorites. So what can you do?
Be mindful of cleaning your knives. The longer food remains on the blade, the more it can damage the surface. Wash your cutlery in gentle dish soap (Dawn is great). Dry them immediately and put them away. Don’t let them stand in water.
To Sheath or Not to Sheath
Manufacturers have developed magnetic systems for storing your blades, and the reviews are positive. They’re incredibly handy as you can grab your desired knife without searching through drawers. The fact that they have airflow also helps prevent rusting. The strips or stands are good for sanitation and take up little (to no) countertop real estate.
The best magnetic knife holders have magnets inside the wood, out of contact with the cutlery. They hold your pieces firmly. It’s not a bad idea to put tip protectors in place if someone accidentally knocks the knives.
A more traditional method is sheathing. There are five types of sheaths commonly seen on the market.
- Kydex is somewhat like plastic but far tougher. It weathers changes in the environment without any issue. Kydex is waterproof. Because it’s a rigid material, you may have to sharpen and hone your edges periodically.
- Leather: There are a variety of leather sheaths, meaning you can buy one that suits your personal style. To maintain your leather sheath, keep it clean. If it gets wet, air dry it. Condition the exterior about every six months to prevent cracking.
- Nylon: Easy to find and use and fairly cost-friendly. They’re not the best, but functional in a pinch. Over time, a good blade may cut right through it.
- Plastic: Not the most optional sheath. Yes, it is waterproof, but leather and Kydex are far more durable. Plus, plastic can dull a knife edge quickly.
- Wood. Even though people used wood as a sheath for knives for eons, it’s not highly favored. It retains moisture and puts the blade at an increased risk of rusting.
Rid the Rust
On the occasion when you find rust on your cutlery, don’t just toss it in the garbage bag! Here are some remedies you can try before giving up.
- Lemon or White Vinegar. Soak the blade for about five minutes in either (no longer!). Wipe it afterward with a soft sponge. You may have to repeat this a few times to clean up everything. Note that you can just cut a lemon in half and run it along the blade, too.
IMPORTANT: Do not use abrasives for cleaning other than some sea salt.
- Baking Soda: This is best for light rust stains. First, make sure the knife is clean and dry. Create a paste with the baking soda and apply it on the metal. Leave it for an hour. Now, take a soft toothbrush and work on the rusted areas. Remove the paste, wipe, and dry thoroughly.
- Potato treatment: Put your knife into a potato. Leave it for two hours. Wipe it down and see how it looks. If there’s still rust, try using another method as your second step.
- Onions (yeah, it sounds like we’re making stew). Slide a sliced onion up and down the blade. The same component in onions that makes you cry (sulfenic acid) helps get rid of the rust..
Knives that Have a High Level of Rust Resistance
If you’re not keen on cleaning the rust off your knives, you can consider buying knives that resist rust. Ceramic knives, for example, don’t rust…at all! Zinc-coated steel keeps a blade safer and longer. Chromium-Nickle-iron blades are less subject to rust if more than 10% Chromium is present.
Should you want durability at a decent price, stainless steel is the way to go. Stainless cutlery doesn’t rust easily, and it is fairly easy to sharpen. Think of stainless as an all-purpose choice until you want to move into fancier blades.