How to care for a carbon steel knife: cleaning, patina and rust

Wash a carbon steel knife by hand straight after use, dry it at once and now and then wipe the blade with a drop of food-safe oil. Never leave it wet, in the sink or in the dishwasher. The grey or bluish colour the blade turns over time is patina, not damage: it actually protects the steel. Orange spots are rust and rub off with a little effort.

Why choose a carbon steel knife?

Carbon steel, also called non-stainless steel, takes a very keen edge and is easy to sharpen. Traditional paring knives and many professional kitchen knives are made of it. The price is maintenance: without the chromium that makes stainless steel stainless, the blade reacts to water and acids. The product page of every knife in our shop names its material, so you know which one you are buying.

How do you clean a carbon steel knife?

• Rinse the blade after cutting acidic food such as tomatoes, citrus or onions, even if you are not finished cooking.
• Wash with warm water and a little washing-up liquid, then dry the blade and the handle with a tea towel straight away.
• Store the knife dry, in a block, on a magnetic strip or in a sheath. Loose in a drawer, the edge knocks against other tools.
• A wooden handle likes a drop of oil now and then as well.

Is the discolouration on my knife a problem?

No. A grey, blue or slightly mottled layer that forms when you cut food is patina, a stable oxide layer. It makes the blade less prone to rust. Some cooks encourage it on purpose. Only orange or reddish brown spots are rust.

How do you remove rust from a carbon steel knife?

Light rust comes off with a cork or a soft cloth and a paste of bicarbonate of soda and a few drops of water. For stubborn spots, use a fine scouring pad and rub along the length of the blade, not across it. Rinse, dry and wipe on a thin film of food-safe oil afterwards.

How do you sharpen a carbon steel knife on a whetstone?

1. If you have a water stone, soak it in water until no more bubbles rise. An oil stone takes a few drops of honing oil instead.
2. Lay the stone on a damp cloth so it cannot slide, coarse side up.
3. Hold the blade at a low, steady angle to the stone, roughly 15 to 20 degrees, and push it across the stone edge first, from heel to tip.
4. Repeat on the same side until you feel a fine burr along the whole edge on the other side.
5. Turn the knife over and sharpen the other side the same way.
6. Finish with a few light strokes per side on the fine side of the stone, then rinse and dry the knife.

Between sharpenings, a few strokes on a honing steel straighten the edge and keep it cutting well.

Which cutting board is best for a carbon steel knife?

Wood or plastic. Glass, stone and ceramic boards blunt any edge within a few cuts.

Knives in our range

You will find paring knives, chef's knives and cutting boards in Cutting Tools, and every carbon steel item under carbon steel. Also caring for cast iron? Read how to care for a cast iron pan.