How to Remove Rust From Knives

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Updated August 2026 · 6 min read · UK Japanese-steel knife specialists

How to remove rust from a knife, step by step

1. Wash and dry the blade so you can see exactly where the rust is.
2. Mix bicarbonate of soda with a little water into a thick paste.
3. Spread the paste over the rust spots and leave it for about 30 minutes.
4. Scrub gently along the blade — never across it — with a soft toothbrush.
5. Rinse in warm water and dry immediately with a soft cloth.
6. If any rust remains, repeat with a white-vinegar compress, then dry and oil lightly.

Why does stainless steel rust at all?

Rust is iron oxide — the flaky orange-red substance that forms when iron reacts with oxygen in the presence of moisture. Stainless steel contains iron, so it can rust. "Stainless" only ever meant rust-resistant.

What makes it resistant is chromium. Chromium reacts with oxygen to form a very thin, invisible passive layer across the surface, and that layer is what keeps water and air away from the iron underneath. Its clever trick is that it re-forms by itself when scratched — which is why a stainless knife survives daily use without corroding.

Rust appears when that layer is prevented from re-forming. In a kitchen the usual culprits are:

• Sitting wet — left in the sink, on a damp draining board, or put away before drying.
• Chlorides — bleach, some harsh detergents and dishwasher salt attack the passive layer directly.
• Prolonged contact with acidic or salty food left on the blade.
• Contact corrosion — storing a knife touching cast iron or carbon steel.

A dishwasher manages to combine several of these at once, which is why we don't recommend putting good knives in one. The mineral content of hard tap water can contribute too — more on that in how water damages a knife.

If the knife in question is a Japanese VG10 or AUS-10 blade, our companion guide on removing rust from a Japanese chef knife covers the extra care a harder, thinner edge needs.

Five ways to get rust off a knife

For light to moderate rust, everything you need is probably already in the kitchen. Severe pitting may not come out completely — but it is always worth trying before you give up on a knife.

1. Bicarbonate of soda — the best all-rounder

Mix bicarbonate of soda with a splash of water into a thick paste, spread it over the affected areas and leave it for about 30 minutes. Then work along the blade with a soft toothbrush, rinse in warm water and dry thoroughly straight away. It is mildly abrasive and mildly alkaline, which is exactly the right combination for surface rust, and it is gentle enough not to mark the finish.

2. White vinegar — for more stubborn spots

White vinegar contains acetic acid, which dissolves iron oxide. Soak a cloth in it and lay it over the rusted section for about five minutes, or stand just the affected part of the blade in a shallow dish of vinegar. Don't leave it much longer — prolonged acid contact can dull the finish. Rinse and dry immediately afterwards, then follow with the bicarbonate paste if any rust remains.

Use plain white vinegar only. Malt, balsamic and wine vinegars can stain the steel.

3. Lemon and salt

Sprinkle salt over the rusted areas, squeeze lemon juice over the top and leave it for an hour or two. The citric acid works on the rust while the salt gives you a mild abrasive; scrub with the lemon rind itself, then rinse and dry. It smells considerably better than the vinegar method and is about as effective.

4. A cut potato

It sounds like a joke, but potatoes contain oxalic acid — the active ingredient in a number of commercial rust removers. Cut one in half, dip the cut face in a little washing-up liquid or bicarbonate of soda, and rub it firmly over the rust. Rinse and dry when the rust lifts.

Rub with it rather than leaving the blade embedded in a potato for hours — that just holds moisture and acid against the steel, which is what caused the problem in the first place.

5. An onion

The gentlest of the lot, and only worth trying on the very faintest specks: slice through a raw onion a few times. The sulphenic acids released as you cut can lift the lightest surface discolouration. Rinse and dry afterwards. If the rust is properly established, skip straight to the bicarbonate paste.

What not to use

• Steel wool and scouring pads. They will shift rust, but they leave a field of fine scratches — and a rougher surface traps moisture and rusts faster next time. On a polished or Damascus-patterned blade the damage is permanent and obvious. A soft brush and a little patience get there without the cost.
• Bleach or anything chlorinated. Chlorides attack the chromium layer directly. They make rust more likely, not less.
• Aggressive power tools. A wire wheel or rotary brush removes far more than rust and will ruin the grind.
• Long acid soaks. Five minutes in vinegar is treatment; an overnight soak is damage.

Stopping it happening again

• Wash by hand in warm water with a mild detergent, and dry the blade straight away. Never leave a knife to soak.
• Keep knives out of the dishwasher. Heat, harsh detergent and knocking against other items are a bad combination for any good blade.
• Store them where air can circulate — a rack, a block or a magnetic holder — rather than sealed in a damp drawer. Our guide to knife blocks covers the options.
• Don't store knives touching cast iron or carbon steel items.
• Wipe acidic and salty foods off the blade as you go rather than at the end of cooking.
• A very light wipe of food-safe oil two or three times a year is plenty for stainless. You don't need to oil it as often as you would a true carbon steel blade, and overdoing it does more harm than good.

Beyond rust, the rest of the routine is covered in our complete knife care guide and in the mistakes that quietly damage knives.

Frequently asked questions

Can stainless steel knives rust?

Yes. "Stainless" means rust-resistant, not rust-proof. Chromium forms a protective layer on the surface, but salt, acid, prolonged damp and dishwasher detergent can break that layer down and let spots form.

What is the easiest way to remove rust from a knife?

A bicarbonate of soda paste left on for about 30 minutes, then scrubbed gently along the blade with a soft toothbrush and rinsed. It is the gentlest method that reliably works on light surface rust.

Should I use steel wool to remove rust from a knife?

No. Steel wool and scouring pads scratch the finish and leave a rougher surface that traps moisture and rusts faster afterwards. Use a soft toothbrush with a bicarbonate paste, or a white-vinegar compress, instead.

How do I stop my knives rusting?

Hand-wash rather than using the dishwasher, dry straight away rather than leaving knives on a draining board, store them where air can circulate, and give the blade a very light wipe of food-safe oil a couple of times a year.

Is a rusted knife safe to use?

Once the rust is fully removed and the blade rinsed and dried, yes. If the rust has left deep pits along the cutting edge, the knife will chip more easily there and is better re-ground or replaced.

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