Carbon vs Stainless Steels
Although stainless steel is the most common material for kitchen knives, carbon steel is often the preferred choice of culinary professionals. That’s because a carbon steel blade, when properly cared for, holds a sharp edge better than stainless steel. The flip side is that “proper care” of carbon steel involves a bit more day-to-day maintenance.
Clean while you Cook
One of the most important steps in taking care of your carbon steel is keeping the blade clean. That means wiping down your knife while you cook. It may seem tedious at first, but it will keep your blade from rusting. This is especially true when working with acidic foods, like lemons and tomatoes, which tend to be particularly tough on carbon steel. When you are done using your knife, wash, rinse, and dry immediately after use.
Never let carbon steel knives rest with debris on them, “soak” in the sink, or air dry. Doing so will guarantee they will rust
OIL BETWEEN USES
After you are done chopping and have rinsed and dried your knife, drop 2-3 small drops of oil on each side of your blade and wipe it down with a paper towel so the whole blade has a thin coating of oil on it. This helps protect the carbon steel against rust from any moisture that might be in the air. You can use any food safe oil, including olive oil, to wipe your knife down between uses. I personally recommend this brand of mineral oil.
Why is my new knife getting “stains”?
Most of us are familiar with oxidation in the form of rust, which carbon steel is particularly prone to if it isn't kept dry and clean, but carbon steel is also susceptible to another type of oxidation that doesn't affect stainless steel.
Magnetite is a less destructive type of oxidation that affects just the surface of carbon steel. This process is what's responsible for developing the carbon steel patina that changes the color of the metal from its shiny chrome-like finish to a dull gray. Any carbon steel connoisseur will be familiar with magnetite as the pattern of streaks, spots, and swirls that a well-used carbon steel blade will develop over time. The patina does not affect the function of the blade, but does give it a wonderful aesthetic, and it actually helps protect the blade from further oxidation (including rust)!