How to Remove Rust from a Blade

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Co-authored by Ryaan Tuttle

Last Updated: April 12, 2023 Approved

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When it comes to tools, nothing is better than having a sharp blade that can cut through anything. Unfortunately, metal blades are prone to damage when exposed to water. Maybe you left your favorite kitchen knife in the sink overnight, or perhaps you stored your best saw blade in a damp corner of the garage. No matter what kind of blade you have, you can wash off rust with a few household cleaners. Rust is unpleasant and blunts tools, but it doesn’t have to be the end of your blade.

Steps

Method 1

Method 1 of 3:

Using Baking Soda on Light Rust

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1. 1
   Wash off the blade with a mild dish soap water to remove debris. Fill a bowl with about 1 cup (240 mL) of warm water, followed by 1 teaspoon (4.9 mL) of dish detergent. Stir in the dish detergent until it’s soapy. Then, put the blade into the water and scrub it with a clean sponge. Wash off as much loose rust, oil, and other debris off the blade as possible.

   • Things like dirt and oil can prevent baking soda from soaking into rust stains. Clean the blade so more of the rust comes off later.
   • In most cases, you can use whatever dish soap you have available. Avoid using anything harsh with added chemicals or scents. If the soap is designed for cutting through tough grease, it’s probably too strong for your blade.
2. 
   2
   Mix 3 parts of baking soda with 1 part water in a bowl. For example, mix about 1 tablespoon (14.40 g) of baking soda with 1 teaspoon (4.9 mL) of water. Stir them together until they form a paste. Make enough of the paste to cover all of the rusty spots on the blade.

   • Baking soda is stronger and easier to apply as a paste, but sometimes, plain baking soda is enough to eliminate rust. Just sprinkle the baking soda onto the blade, scrub it into the rusty spots, and rinse it off.
   • Baking soda is useful on thin and lightly-rusted blades. You can always use baking soda with vinegar as well by mixing them in equal amounts for a safe, neutral cleaner.
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3. 
   3
   Spread the baking soda over the blade with a toothbrush. Dip the brush into the bowl to scoop up some of the paste. Make sure all of the rust spots are well-covered. To ensure you don’t miss any, start at the handle and work toward the tip.

   • Cover every spot. You can’t use too much baking soda on it.
4. 
   4
   Scrub the baking soda into rust spots with a toothbrush. Work along the length of the blade from the handle to the tip. Treat each spot to remove as much of the rust as possible. Scrub in the direction of the handle and tip rather than the sharp edge. When you’re done, remember to flip the blade over to clean its other side as well.

   • If the toothbrush isn’t working, you could switch to a scouring pad or another slightly-abrasive scrubber.
5. 
   5
   Brush the blade with super fine steel wool to eliminate older rust stains. Press the steel wool pad gently. Move it back and forth along the blade’s length. Work toward the tip, scrubbing out rusty spots as you come across them. Apply more of the baking soda paste as needed to keep the spots covered while you’re scrubbing them.

   • Super fine steel wool has a grade code of #0000. If you see that number, then you have the softest kind of wool least likely to scratch a good blade.
   • Steel wool can scratch metal, so be careful. Scrub lightly and keep the pad away from the sharp edge of the blade.
   • You could also use a wire brush or a slightly-abrasive sponge to eliminate older rust stains.
6. 6
   Rinse the knife under warm water to clean off the rust. Turn on the sink tap and wait for the water to warm up. Then, hold the knife under the water. Check for any remaining rust flakes still stuck on the metal and try scrubbing them out with a toothbrush.

   • The water won’t damage your blade as long as you wipe it dry before storing it. Take plenty of time making sure that the blade looks clean and doesn’t need another round of baking soda paste.
7. 
   7
   Wipe water off the blade with a clean microfiber cloth. Hold the cloth over the blunt side of the blade and wipe the sides clean. Then, look for any signs of moisture or rust still on it. Make sure the blade is completely dry before attempting to store it. If it’s still a little rusty, clean it again first.

   • You could try using more baking soda if the rust stains look newer and seem shallow. For example, let the baking soda soak into the rust for an hour before washing it.
   • If the blade has deep rust stains, try using vinegar or another cleaner first, then treat it a second time with baking soda to remove any marks still lingering on it.
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Method 2

Method 2 of 3:

Soaking Stubborn Rust Stains with Vinegar

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1. 1
   Fill a cup full of white vinegar. If you use a cup, you can stand most blades up to let them soak. This will be a little more difficult with longer blades. To clean long blades, fill a pan, such as a baking sheet, instead. Add enough vinegar to cover the rusted parts of the blade.

   • Apple cider vinegar is also safe to use, but other types of vinegar may stain your blade. If you don’t have vinegar, you could use citric acid or lemon juice instead.
   • To make a stronger cleaner, pour in ¼ cup (75.0 g) of salt. It makes the vinegar more acidic so the rust breaks down faster than normal.
   • Vinegar is effective no matter how rusty a blade is, but it is also acidic enough to damage metal. Be careful with it, and try using baking soda if your blade isn’t very rusty.
2. 2
   Soak the blade in the vinegar for at least 5 minutes. Place the blade in the vinegar so the rusted bits are submerged. Set a timer and come back to it afterward. Don’t let the blade soak for too long in case the vinegar starts to wear away the metal.

   • Another option is to dampen a cloth in vinegar, then wrap it around the blade. It’s useful if you’re having a hard time finding a way to keep a long blade submerged.
   • Some people soak their blades as long as overnight. You can try this if your blade is in bad shape, but you usually won’t have to.
3. 
   3
   Wipe off the rust using a mildly abrasive scouring pad. Start at the handle and work toward the tip of the blade, scrubbing off the rust spots gently. Most of it will come off without much difficulty. Flip the blade over to scrub the other side as well.

   • For example, scrub the blade clean with the green side of a kitchen sponge or get a separate scouring pad. You could also use something like an old toothbrush to clear off the loose rust.
   • If you’re having a hard time removing any rust spots, make sure that the blade is still damp. You can stick it back in the vinegar and scrub it while it’s submerged.
4. 4
   Rinse the blade under warm water to clear off the vinegar. You might be a little wary about exposing your cleaned blade to water right away, but it will be fine. Turn on the sink tap, let the water warm up, then rinse it off. Wash off as much of the rust as possible, too.

   • If you’re looking for a stronger cleaning solution, apply a little dish soap to the blade and scrub it clean before rinsing it off.
5. 5
   Wipe the blade dry with a clean microfiber cloth. Thoroughly dry off both sides of the blade to ensure all of the moisture is gone. When you’re done, check the blade’s condition. Vinegar is very effective on rust, but it might not eliminate all of the rust in one go.

   • Make sure the blade is completely dry. Any moisture left on it could cause it to rust again.
   • If the blade is still a little dirty, scrub it again with more vinegar. You could also try baking soda or a harsher scrubber like steel wool.
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Method 3

Method 3 of 3:

Polishing Damaged Blades with WD-40 and Sandpaper

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1. 
   1
   Scrub the blade with a sponge dampened in soapy water. Pour about 1 cup (240 mL) of warm water into a small bowl. Next, mix in 1 tablespoon (15 mL) of a mild dish detergent. Dip a sponge into the water to wash the blade clean, then rinse it under running water afterward.

   • Clear off any debris left on the blade before attempting to treat the rust. The WD-40 does a better job without the debris in its way.
   • Use a mild dish soap without added chemicals or artificial scents. Avoid ones that are made for tough grease, for instance.
2. 
   2
   Spray WD-40 over the rust spots on the blade. Hold the canister about 6 in (15 cm) from the blade. As you start spraying, sweep the nozzle along the length of the blade. Make sure all the rusty spots are covered. Go back over any spots you missed the first time.

   • If you don’t have WD-40, you could use another rust removal product. For example, try getting a cleaner containing oxalic acid.
   • Save WD-40 and other rust removers for blades you don’t use to prepare food. They work well on machetes or Damascus steel, for instance
3. 3
   Wait 10 minutes for the WD-40 to soak into the blade. Place the blade on a soft towel so you aren’t stuck holding it. Then, set a timer and check back later. The rust will be softened enough to scrub off the blade.

   • If the rust is bad, you could soak the blade in the WD-40 for longer. Try leaving it for up to 3 hours to treat light rust or 12 to 24 hours for heavy rust.
4. 
   4
   Use 400-grit sandpaper to scrub rust off of the blade. Hold the blade down by its handle, then press the sandpaper against it. Apply a very light amount of pressure so you don’t inadvertently scratch it. Then, scrub the rusted spots in the direction of the blade’s tip. Flip it over to scrub the other side afterward.

   • Always work along the length of the blade. Also, be careful to avoid touching its sharp edge, since the sandpaper could blunt it.
   • You could also use super fine steel wool or a wire brush, but be gentle to avoid leaving scratches on the metal.
5. 
   5
   Treat the blade repeatedly with WD-40 if it’s still rusty. Deep rust stains take some extra elbow grease to buff out, so don’t give up if your blade isn’t how you want it to be right away. Spray more WD-40 over the rusty spots and wait another 10 minutes for it to soak in. Then, rub off as much dust as you can again with a fresh piece of sandpaper. Depending on the state of your blade, you might have to go through all the steps several times to make it shine again.

   • Alternatively, switch to alternative cleaners like rust removal products containing oxalic acid. Vinegar and baking soda are also good choices if the remaining rust isn’t too bad.
6. 6
   Apply a fresh coat of WD-40 to protect the blade when you’re finished. Hold the blade over a towel or another surface, then spray it all over. To ensure you coat the entire thing, start at the handle and move toward the tip. Flip it over to cover the opposite side as well. The additional coating of WD-40 lubricates your blade and protects it from rusting again.

   • Many people use mineral oil to rust-proof blades. If you have some, dampen a cloth in it and then wipe the cloth across the blade.
   • If you have a kitchen knife, finish it with a coat of food-grade mineral oil instead of WD-40.
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Tips

• Some common foods, like raw potatoes, are effective on light rust if you’re out of options. After sprinkling your blade with salt or baking soda, rub it with a potato for a quick and easy treatment.
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• The best way to deal with rust is by preventing it. Wash and dry your blade after each use, then keep it in a dry spot away from moisture.
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• Treat your blades with a rust inhibitor at least once a year, such as by applying WD-40 or using mineral oil if you use the blade to prepare food.
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Warnings

• Many treatments, including vinegar and steel wool, can further damage metal. Treat your blades sparingly and with caution to preserve them.
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Things You’ll Need

Using Baking Soda on Light Rust

• Bowl
• Mild dish detergent
• Baking soda
• Toothbrush
• Super fine steel wool
• Microfiber cloth

Soaking Stubborn Rust Stains with Vinegar

• Bowl
• Mild dish detergent
• White vinegar
• Scouring pad
• Microfiber cloth

Polishing Damaged Blades with WD-40 and Sandpaper

• Mild dish detergent
• WD-40
• 400-grit sandpaper