Carbon steel — the traditional material for making knives long before stainless steel even existed — has a mystique and sexiness all its own. In Japan it was the traditional material for making samurai swords, and then later, kitchen knives. Preparing food with a knife made of carbon steel links the user to a 1300-year-old history. Examine the frosty beauty of a Masakage Shimo or the rustic, raw aesthetic of the Moritaka Ishime and you too will feel that connection.
Knives made of carbon steel tend to keep an edge much longer than their standard stainless-steel counterparts. Unfortunately, that extended edge life comes with a trade-off. Carbon steel is susceptible to the destructive force that is RUST. (dun dun dunnnnnn) But do not fret, this isn’t the end of the world. Below we will show that you (yes, you!) too can own and care for a carbon steel knife successfully. (And so will your children and your children's children as your heirloom gets passed down through generations.)
Some knives, like the Fujiwara Denka or Masakage Yuki and Koishi lines have a carbon steel core with stainless steel cladding. These knives require less maintenance as the carbon steel is only on the very edge of the knife. The tips that follow are meant for those of us with or looking to purchase knives made entirely with carbon steel, but we encourage anyone curious about carbon steel care to read on.
You will find, as I have, that these blades will change colour becoming grey or even black as they are used. Consider how a copper roof becomes green over time, or a leather jacket becomes more beautiful as it ages.This is called a patina and it’s a good thing! A patina develops on carbon steel when it is exposed to the air for extended periods of time or to acids for short periods of time. It’s a type of oxidation that helps ward off the evil red rust that eats away at steel and destroys your knife. Black or grey = good, red or orange = bad.If you’re the impatient type, are also ways to speed up the process.
As you use your knives on foods like onions, tomatoes or other acidic food you will notice the patina getting darker. My carbon knives have a strong patina that I acknowledge as a reward for using exceptional knives, each blade being unique.
My grandpa had a favourite hunting knife. When he’d come home from a hunting trip he’d wash it, run it over a sharpening stone, and finally oil it with Camellia oil. Knifewear sells a version of that same oil called Tsubaki oil. It is 100% food grade, considered hypoallergenic, and it won’t go rancid the way many food grade oils can. Applying a few drops to your knife on a weekly basis for the first few months will keep the steel from oxidizing due to moisture (destructive red rust), but still allows for a healthy patina to develop.
In the culinary world there is a term used by chefs called “Mise en Place”; everything in its place and a place for everything. When I set up my cooking area it always includes two tea towels, one damp and one dry, folded up next to my cutting board. The former for wiping food residue off my blade, the second to dry the blade to prevent rust. It was easy to get into the “one two” habit of wiping off my knife. While I’m prepping, I generally wipe my knife whenever I wash my hands or between food stuffs.When finished prepping, I wash my knife with soap and water, taking care not to scrub the patina off my blade.
Found rust on your blade despite being a good student and adhering to everything you’ve learned here? If you catch it early, you have no worries! Knifewear Rust Eraser or a kitchen scrubby can usually get that right off. If it’s a more serious case you can also gently rub the blade with baking soda, Bartender’s Keeper or even some 1000 grit sand paper. Use a gentle touch so you aren’t taking off all the patina you developed.
This might all sound like a lot of work for a simple kitchen knife, but I promise it’s worth it. I like to think of a new carbon steel knife like a puppy. A brand new puppy might pee on the carpet; a carbon steel knife might rust. When you train a pup, yes, you’re training your dog, but you are also training yourself to engage in good habits. Provided things go well, your day to day life with your dog becomes more fun than work and everyone is happy. So it is with these knives. The connection to one’s tools and to their history makes everyday prep work a joy to partake in. I don’t know about you, but when I enjoy a job, that job gets done more often and with more care than those I don’t.