What is a Carborundum Stone? (Complete Guide)

Carborundum stones are sharpening stones made from silicon carbide. This is a rigid material; it can sharpen every knife that you have. Taking a look at the Mohs scale, silicon carbide has a hardness score of 9-9.5. Now that is hard!

You may not realize it, but silicon carbide is all around us. Its hardness makes it a very useful material. Aside from sharpening stones, silicon carbide is also used in sandpaper, grinding wheels, and bulletproof vests!

There are three kinds of sharpening stones: water stone, oil stones, and diamond stones. Carborundum stones are oil stones. This means that while sharpening, you’ll have to oil them now and then. You can use water on new carborundum stones, but once they are oiled, water will no longer be effective.

One advantage you can enjoy with oil stones is that they last so much longer than water stones. It’s no surprise since silicon carbide is such a hard material. Even if you sharpen a lot of knives, you can be sure your carborundum stone will stand strong. You won’t have to worry about it wearing down anytime soon.

What are Carborundum Stones Used For?

Now that you know what carborundum stones are, you might be wondering what they are for? What makes them different from other types of sharpening stones? What should you use them for?

As said before, what sets this stone aside from others is how hard it is. It’s only 1 score away from diamonds in the Mohs scale, and diamonds are the hardest material you can get. That’s why unless you have a diamond knife, this will sharpen it with ease. All other knives, even hard types like ceramic knives, can be sharpened by carborundum stones. You never have to question whether it can get the job done.

Not only can they sharpen anything, but carborundum stones can sharpen anything fast. This is one of the things that I love about this sharpener. Compared to other types of oil stones, nothing sharpens quite as fast as silicon carbide.

If you have a dull blade, this is the best way to get it sharp in no time. That’s why when I get an old blade that can’t cut anything anymore, this is my stone of choice. It can go from blunt to razor-sharp with a few strokes. Restoring blades has never been so fast.

That said, carborundum stones are not the best for finishing. If you’re looking for a fine finish on your blade, other sharpeners will do better. This is because of how hard silicon carbide is. If you inspect your blade after using a carborundum stone, you’ll find that it’s a bit coarse. What I like to do is use my carborundum stone to get the sharpness I want, then use a finer stone for a smoother finish.

How to Sharpen a Knife with a Carborundum Stone?

Being an oil stone, it’s very important to oil your carborundum stone before sharpening. This will make your sharpening experience a lot smoother and safer. Without oil, it’s very easy to damage your blade. Remember, silicon carbide is very hard, without a lubricant, your blade will be damaged.

One question I get a lot from new enthusiasts is what oil to use for sharpening. It may surprise you to find out that the answer is any oil. As long as it’s oil, you can use it to lubricate your carborundum stone. But just because you can use any oil, doesn’t mean you should. Some oils are better than others when it comes to sharpening.

Perhaps the best oil you can use is honing oil. Honing oil not only greases the stone well, but it also gets rid of metal debris. If you don’t have that around, what I like to use is mineral oil.

Mineral oil is great because it is a light oil with no strong odors. This is what you are generally looking for in sharpening oil. A lot of people reach out for the nearest oil they can get, which is often cooking oil. While this will work fine, it isn’t good for your carborundum stone. The problem with cooking oil is that it tends to harden up. If the oil hardens while on your stone, it will damage it.

You also want to avoid odors with scents. This is for obvious reasons. If you leave these oils on your carborundum stone, it will smell terrible. It won’t damage it in any way, but you’ll have to sharpen your knives with a mask. So stay away from oils that have odors.

Once your knife is oiled, all you have to do now is sharpen. There are different techniques for different knives, but it’s all generally the same. Hold flat of your knife against the face of the stone, and tilt it a little. The tilt angle will differ from knife to knife, but you should tilt it at the same angle of your bevel. This way, when you sharpen, you won’t scratch the flat of your blade.

Once that’s done, slowly rub your knife against the stone. Two hands on the knife and the stone on a flat surface is the best way to do this. I always tell people to sharpen slow and steady. Patience goes a long way in the world of sharpening. After a few strokes, make sure you check for a burr in your blade. Once you feel it, that side is done.

ou want to make sure your carborundum stone doesn’t dry out. Whenever your stone is getting dry, pour more oil on it. Also, if you find that there is a lot of debris on your carborundum stone, wipe it clean before continuing. Both of these will ensure a smooth process.

Check out one of the best Carbordum stone that we use Here

How to Clean a Carborundum Stone?

Every time you are done using your carborundum stone, make sure to wipe it clean. Oil stones tend to get a lot dirtier than other sharpeners, so they need extra care. Wiping your carborundum stone after using will prolong its life a lot. So don’t forget to do this.

If you use your carborundum stone a lot, you will find that over time, it may start to lose its efficiency. Steel debris can get into the holes of the stone and clog it up. And a simple wipe of your carborundum stone won’t do much to remove these. So how do you clean an old carborundum stone?

If you have steel debris on your stone, sandpaper will do the trick. Sand your carborundum stone until the surface flattens out and the steel bits are gone. As with everything else, you want to do this slowly and gently. You don’t want to over-sand your stone.

If your stone is full of dirt and grime, what you need is penetrating oil. When you use penetrating oil, it will loosen up all the dirt and grime stuck in your stone. After spraying, give it a few minutes to soak up the oil. Once that’s done, take a piece of steel wool and rub it against the stone. This will get rid of any grime that is still in there. Finally, take a cloth and wipe your carborundum stone clean.

You can Check our Full Guide to Clean and Maintains Your Sharpening Stone and Sharpening Rod.

My Recommendation For The Best Carborundum Stone

Norton Abrasives IM313 Pro Multi-Oilstone Sharpening System c/w 11-1/2" Coarse Crystolon, Medium Crystolon and Fine India Stones, 4-1/2 Ounce Norton Oil, Plastic Angle Guide and Reservoir Uni
  • Self-contained bench sharpening unit with...
  • Includes three sharpening stones: 100-grit silicon...
  • 1/2 x 11-1/2 x 2-1/2 inch (H x W x D) size of...
  • Durable plastic case has a lid and no-slip rubber...
  • Angle guide to position tool correctly for...

Last update on 2024-07-12 / Affiliate links / Images from Amazon Product Advertising API


A lot of people don’t think a lot about the sharpening stones they use. They use it to sharpen and ignore it the rest of the time. They never learn about or appreciate the fact that sharpening stones have a world of their own.

Choosing a sharpening stone and taking care of it is like taking care of knives in a lot of ways. And it is something that is just as enjoyable. That’s why you should pay more attention to the sharpening stones you have around you. If you have a carborundum stone, make sure it’s clean and efficient at all times. This way, the task of sharpening all your knives will be a lot better and easier!


I’m Ahmed, the guy behind Knifepulse.com. I’ve owned several types of knives and sharpeners over the last few years and have become obsessed with everything to do with knives. I’m always trying to improve my cleaning and sharpening process, and always on the hunt for the next best knife. But when I’m not spending time with my hobby, I’m here, writing about Knives and Sharpeners on KnifePulse to share with you what I learn along the way.

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