Sharpening Bench Knives

Checking the Edge

I work the brown stone until I can see that a new cutting edge is being developed by checking the shine along the edge. This could be as long as fifteen minutes of quite steady work.

sharpening1What you are hoping to developed at this stage is a tin edge. This is a small sliver of metal right at the edge of the blade that is being worked off with the stone. Hold the tool under a bright light. If you turn the blade on its side and look directly down at the blade edge you will be able to see a shiny line … the line is the tin edge.

A razor sharp edge held under the light is almost invisible, there is no shiny line down the center of the blade! If you can see the edge of the tool, it’s not sharp yet.

sharp_edgeAlso check along the sides of the edge. You are searching for any bright spots that stand out along the edge line. These are areas that are “dents” in the edge and have not yet been taken down to the level of the leading edge.

Work the tool on the coarse stone until there are no dents along the cutting edge and the tin edge line is very thin. The “very thin” determination comes with both practice and experience.

 

 

The bench knife above has a razor sharp edge.
Under a bright light the cutting line of the tool is almost invisible.

 

This is an old kitchen knife that has long been neglected.
Note the shiny spots toward the back of the blade showing
dents into the cutting edge. The mid-point of the blade has
become dull. Only the tip of the blade is sharp.
Click here for an enlargement.

Fine White Stone, 8000 Grit

brown-stone-02Next move onto the white fine grain stone. The stone shown in the photo is a Japanese Wet Stone, 8000-grit.  Since this stone is fine grit and more dense than the Japanese brown stone the slurry in much thinner.

Lift the lead of the knife slightly above what you used on the brown stone, about 12-15 degrees. Use the same backwards stokes with the knife. This is now creating a little tighter angle and begins to really move that tin edge. Again, for a new knife I might work about 10 or 15 minutes on the white stone. With this stone you will be able to see the metal removed since it becomes a grayish layer across the stone surface.

Again, check your edge by holding the knife under a bright light. You are checking for any shiny areas along the blade’s edge. A shiny line down the edge means you still are carrying the tin edge and need to work the white stone longer.

The main goal of using the brown stone is to create that tin edge … the main goal of the white stone is to remove the tin edge. At this point in sharpening the tin edge will be so flexible that if you try and gauge the sharpness of the tool by laying your finger down on the tool’s edge, it will “feel” sharp. That tin will move from one side to the other, so you think you are touching a fine angle on the blade. Instead rub your finger from the back edge of the blade toward the cutting edge. You will be able to feel the ridge of the tin edge when you hit the tip of the blade.

 

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