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Before we point out the steps necessary to sharpen a knife or a tool, we need to understand what happens during the sharpening process.
First, the sharpening stone must be wet. Rubbing the edge of the tool enables the dust that is part of the stone to mix with the water. This makes the water turn purplish. This abrasive mixture of water and dust enables the sharpening. This is why rubbing the tool edge on the stone causes wear on the tool.
Knife blades are normally made from one of these kinds of steel:
- Carbon steel. It is soft and easy to sharpen, requiring regular maintenance.
- Stainless steel. It is hard, and holds its sharpness. It requires the use of a fine and abrasive stone.
- Steel 440. Also called surgical steel, it can be can be sharpened very well with a fine, abrasive stone such as the coticule stone.
- Steel 12c27 or sandwik. These types of steel are softer than stainless steel or steel 440 and give excellent results during sharpening.
The two common shapes of knife blades are:
- Flat or slightly curved from the back.
- The classic pocketknife shape that we find on a lot of Laguiole knives and others.
Only the sharp edge of the blade needs to be sharpened with the sharpening stone.
Before using the sharpening stone make sure that the knife blade is in good condition. Otherwise, it may be necessary to reshape the blade using a water grinder, manual grinder or electric grinder. You can also obtain the same result using a fine-tooth flat file. For this it is necessary to put the knife in a vice. File away from the edge until the blade is correctly shaped.
These operations are delicate so we recommend you practice first with an old knife. Your blade is now ready to be sharpened.
Sharpening pocket knives or small kitchen knives
When sharpening you need to anchor either the stone or the tool. For small knives the stone itself must be anchored, for big knives, the knife must be anchored, but we will talk more about them later. The anchored part enables you to maintain the correct angle against the knife edge.
- What angle to use? We recommend a 25% angle. This will give the best edge. A smaller angle of 15% will weaken the edge.
- How to get a 25% angle? It’s easy. See the picture below. First put the knife perpendicular to the stone. This is a 90% angle. Now divide this angle by half and again by half; you now have a sharpening angle of about 25%.
Let’s talk about the sharpening process. The stone is anchored and moistened, the angle is perfect and you just need to push the blade up and down, keeping the same pressure against the stone and the same angle without lifting the blade.
First you sharpen the straight part of your blade using the edge of the stone to guide you. Then, with a circular motion , sharpen the round part of the blade, always using even pressure and keeping the same angle. After sharpening one side of the blade, repeat the same stroke on the other side. How long this will take depends on the state of the blade and the quality of the metal. A stainless steel blade or steel 440 will need more time than a carbon steel blade. By touching you can feel if your blade is truly sharp.
Sharpening large kitchen knives
The knife becomes the anchor. You need to secure it well at the corner of a table or on a workbench. Then, wetting the stone, rub it on the blade in a circular motion on each side of the blade while maintaining the 25% angle and even pressure.
Sharpening scissors
Remember that each blade of the scissors has only one edge. Sharpen this edge using a circular motion. Keep the scissors open to evenly sharpen the blade. After you have sharpened the edge, clean off deposits that built up on the scissors blade. Repeat the same operation with the other side of the scissors.
To summarize, here are the 4 rules to follow for a good sharpening using the sharpening stone:
- Anchor either the stone or the tool.
- Make sure the stone is wet enough
- Maintain the right angle
- Use even pressure
Advice from a professional
- While sharpening a small knife or pocket knife, position your thumb or index finger between the center of the blade and the edge to apply greater pressure on the blade (see sketch). You can also use a finger from your other hand to apply more pressure while rubbing the knife against the stone.
- We have placed a leather strip on the top of our box. After sharpening your knife, use moderate pressure to rub both sides of the blade on the leather, moving away from the edge.
- After sharpening, clean the stone with soap and water.
- Use the sharpening stone regularly to keep your knife sharp.
The abrasive properties of the sharpening stone allow it to be used in a number of different ways.
Professionals: Sharpen your wood working tools, planing blades, scissors, leather machines, blacksmith tools, agricultural tools, etc.
Hobbyists: Sharpen hunting knives, fishhooks, tools for the garden, shears, axes or small tools for model building.
True or False?
- The coticule stone is used only with water.
- TRUE: The non-porous coticule stone mixes water and dust into an abrasive clay.
- You can sharpen a knife using only a grindstone.
- FALSE: The grindstone allows you to reshape an edge, but the size of the grains does not give a good finish. Use of the stone is essential to eliminate waste and to refine the sharpening.
- You can sharpen a knife with a honing rod.
- FALSE: The rod does not sharpen. Repeated strokes of the rod dull the edge of the knife, wearing it out prematurely. The grindstone then becomes essential.
- A stone sharpener with thick grains sharpens better than a fine stone.
- FALSE: The grain of the stone only causes indelible scratches to the steel blade. The fineness of the grain and its abrasiveness gives the best results and does not damage the blade. To sharpen more quickly, you only need to apply more pressure -- but be sure to maintain a 25% angle.
- After sharpening with the coticule stone, ending with a honing rod becomes useless.
- TRUE: Because the fineness of the coticule stone gives a perfect finish, you simply need to a few strokes on the leather, back and forth on each side of the blade. Don’t forget to always rub in the direction of the edge.
- A well sharpened knife must have a long edge.
- FALSE: The length of the edge only brings weakness to the blade; indeed an edge that’s too long requires frequent resharpening. By following our recommendations and by sharpening at a 25% angle you will obtain a short edge that will keep its sharpness longer.
- Sharpening is an art.
- FALSE: By following our advice and by using the sharpening stone, sharpening becomes easy and a real pleasure.
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