See What Happens When You Sharpen a Knife Under a Microscope

See What Happens When You Sharpen a Knife Under a Microscope
Our subject: A knife ready for a new edge.

Anyone who has worked in a kitchen, or any other job that regularly interacts with knives, knows that sharpening is a very important skill. The ability to put a fine edge on a knife allows you to have better working tools at your disposal. Not only is it pleasant to be able to slice and dice easily, it is also safer. Sharp knives are more predictable and there’s less of a chance of you losing control of your blade when overexerting in an attempt to push a dull edge through something.

Typically, sharpening your blade with a kit involves three major steps. Each involves rubbing the blade along a stone meant to grind off imperfections on the surface, which are often called burrs. The steps begin with a very rough stone and work toward a finer and smoother stone.

Knowing the details and results of a process can often help you become better at that process. To help with that, we’ve taken some images with a microscope to show the effects each step has on the blade.

A fairly standard sharpening kit

Here is the raw blade. Though this knife has been sharpened in the past, it is ready for a fresh edge.

Typical usage marks

See how there are lines going in many different directions? This is typical after use. We ultimately want to end up with a nice uniform series of marks on the blade.

Note the nearly flat ridge

Here, you can see the light catching the leading edge of the blade. It is nearly flat, and reflecting light back to the microscope.

The Rough Stone

The first step involves the roughest of the sharpening stones. We’re basically shaping the entire cutting area of the blade here. This ensures there is a uniform angle along the entire blade, which will help in the next steps. This also saves considerable time. You could skip this and go directly to the next stone but shaping the blade would take much longer.

The shaping stone


The Honing Stone

The actual sharpening of the cutting edge begins here. Our bevel, which leads to the cutting edge, is getting smoother. The edge itself is being reduced down to a foil thin point. This extremely thin edge curls a bit since it is thin and fragile.

The honing stone
Note the thin curl of metal at the edge of the blade

The Polishing Stone

The final step smooths out the blade and removes that tiny curl on the cutting edge. What you’re left with here is a nice sharp edge and visibly aligned marks on the blade.

The polishing stone

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I get ridiculously excited seeing people make things. I just want to revel in the creativity I see in makers. My favorite thing in the world is sharing a maker's story. find me at

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Adam Spurgin

I'm a software engineer with too many hobbies and a firm believer that there's not enough hours in the day.

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