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How long a knife stays sharp and how fast it rusts depends on the amount of carbon and other metals in the steel. While all steel knives contain some amount of carbon, some have higher levels than others. High-carbon steel is known for keeping a sharp edge, but it needs constant maintenance to prevent rusting. Stainless steel has lower carbon levels combined with high levels of chromium that keep it rust free, but it will need sharpening more often.
What's the Difference?
Steel is a basic alloy of iron and carbon. It's carbon that makes carbon steel hard enough to use as a knife blade. Any steel knife with a carbon content of 0.8 percent or higher is considered "high carbon." Stainless steel has a comparatively low carbon content -- usually 0.08 percent. Instead of high amounts of carbon, chromium and nickel are added to stainless steel to make it hard enough to use as a knife blade while resisting corrosion better than high-carbon knives..
The Sharpest Knife in the Drawer
High-carbon steel knives are harder than stainless steel and retain the sharp edge longer. Hunters favor high-carbon steel for gutting and skinning large game because the knife doesn't dull partway through the process. You'll put slightly more work into sharpening a carbon steel blade, and corrosion can weaken the blade's edge, causing it to break or chip. Stainless steel is softer and thus easier to sharpen, and you'll need to take care not to bend the edge when sharpening.
High levels of chromium give stainless steel its shine and rust-resistance. At minimum, stainless steel contains 10.5 percent chromium compared with about 3 percent for carbon steel. Steels between 3 and 10 percent chromium are often sold as "rust resistant," "semi-stainless" or "stain free." The high levels of chromium in stainless steel stand up well to kitchen applications where acids from food would quickly corrode carbon steel.
Care and Cleaning
Stainless steel knives are easy care: just wash with soap and water, air-dry or wipe with a cloth and put away. High-carbon knives need diligent maintenance to keep them from rusting. Clean it after each use to remove acids that promote corrosion, then apply a thin sheen of knife oil on the blade to protect the steel. While you can find high-carbon kitchen knives, most chefs and home cooks prefer stainless steel for convenience. Carbon steel is the knife of choice in outdoor situations where extended sharpness is worth the extra maintenance.
- Knife Depot: Types of Knife Blade Materials
- Spyderco Knives: Steel Element Information
- Fabricators and Manufacturers Association: Carbon Content, Steel Classifications and Alloy Staeels
- Bosun Supplies Company: Stainless Steel Info - What You Need to Know
- Stainless Restorations: Frequently Asked Questions about Stainless Steel
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