Sharpening Carving Tools
Bench Knives, Chip Knives, Flat Chisels
By L.S. Irish
Sharpening is not that hard and it is something every carver should know how to do for themselves. Your are going to need a couple of grades of sharpening stones, a strap and some rouging or compound, and a few sheets of newspaper. I personally prefer the ceramic stones we are currently carrying. Having used quite a few different varieties these seem to give me the best results.
Sharpening Stones and Strop
Sharpening stones are available in a variety of grits and created from a variety of mineral compounds. You will find them listed in the catalogs under the titles of Arkansas Wet Stones, Diamond Hones, Ceramic Stones, Japanese Wet Stones, etc. Some sharpening stones require a lubricant as oil or water, others do not. Read the instructions for use and care of your stones that comes from the manufacturer.
Again, my preference is the ceramic stone. They require no lubricant, so are used dry. Small in size, about 4 to 5 inches long they are easily stored right in with my carving tool, always within reach. Finally, but most important, they do not develop a sharpening gouge or dip from use. These stones always provide a flat surface thus creating a flat edge. They clean up easily with soap and water, removing any of the filings for the next use.
Many Techniques for Sharpening
There are many ways (techniques) for sharpening and the best one is to find something you are comfortable with and keep doing it! I say this first because ever time you change the technique you use to sharpen, you change the angle of the edge you are creating. That mean having to start all over each time to create a new leading edge to the knife. So pick one way and stick with it for a while. This means about 8 to 10 times … enough to really develop a good edge.
It has been my experience that no knife or chisel becomes perfectly sharp on the first honing. In fact, it often takes several sessions of sharpening then using the tools to finally achieve a razor sharp edge. So be patient with the technique you are trying. Sharpen some, whittle some, sharpen again … fairly soon you will realize that the tool has developed that wonderful cutting edge.
Coarse Stone, 800 Grit
I start with my brown coarse stone. The stone shown in the photo is a Japanese Wet Stone, 1000-grit, that creates a thick mud-like slurry as the blade is pulled across the water soaked stone.
Lay the knife on it’s side flat against the stone. Now lift the back edge of the knife slightly off the stone. Imagine lifting it just enough to be able to slide four or five pieces of typing paper under the back edge. This gives you an angle of about 10-12 degrees.
The tighter the angle to the stone the finer edge the tool will receive. Tight angles mean less steel biting into the wood. For any knife that is used to make stop cuts or line cuts I like a very tight edge. Chisels and gouges do not require that tight an angle so you may wish to lift these tools higher off the stone. These are sharpened around 20 to 25 degrees. Follow the manufactures angle as much as possible with a new tool. After you have learn how the tool “feels” in use you can easily adjust that cutting angle to fit your needs.
Pull the knife along the stone moving away from the cutting edge. When the stroke is complete turn the knife over and repeat for the other side. What you do to one side of a chip knife or bench knife your repeat on the other side. Now you are beginning to developed a double edge.
I think just about everyone has seen the American Old West movies where the barber is talking to the gunfighter, who is about to get a shave. As they converse the barber is honing the razor on a leather belt strop. It’s that flowing pull, flip, and pull again stroke for which you are looking.
Once you have developed a good edge, start any sharpening sections with the white fine grain stone. The coarse brown stone is only used to developed the angle, after that you only want to maintain that angle.
For straight chisels you want a single edge tool, not a double edge as on the bench knife.
Southwest Animals Pattern Package
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.
>What 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.
Also 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.
Fine White Stone, 8000 Grit
Next 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.
Honing Strop and Rouge
Move onto the strop. A good strop has two sides to it, one of rough leather and one of smooth hide. On the rough leather side rub in a good layer of rouge. I use red oxide, but there are many different rouging compounds that can be tried. Lay the blade all the way down onto the surface of the rouge, pull away from the cutting edge in nice long strokes! This is the stage where you will finally lose all the tin edge. You can never strop too much. For a new tool, about 15 strokes per side. Flip the strop over and work the tool across the smooth leather. This side gives that wonderful polished look.
Now at this point you can check if the tin edge is gone by looking directly down at the blade edge. If that edge is has a fine shiny line along it you still have the tin edge. If the blade edge has no shine, you did it!
Newspaper Polishing
My last step is an old – old sharpening technique from way back. Get a couple of sheets of newspaper that have either lots of tight writing on them or a big black picture. You are looking for an area of the newspaper that is heavy with printer ink. Just as you did with the strop pull the knife along the newspaper, one direction, flip, the other direction. I usually work the paper until the ink where I am working has turned shiny.
I am not sure that many use the newspaper any more. Originally it was the lead in the printers ink that acted as a rouging compound. I still do it because the ink does work as a polisher even though it no longer contains lead and the fine tooth of the paper gives that last little “lick” to the blade.
My father, who taught me how to carve, always checked the sharpness of the tool by holding up an edge of the newspaper with one hand. One corner of the paper hung free into the air. On that corner he would lay his knife and make a cut. If the paper “folded” under the knife edge it wasn’t sharp enough for him, because a razor edge will slice the paper without bending it.
As a beginning carver, this use to “discuss – discourage – depress” me. It seemed that as hard as I tried my paper always folded. But after just a few sessions of practicing sharpening I too could “slice the paper clean”.
With a new blade it might take several turns of sharpening to get that razor sharp edge you want. It seems to me that sharpening then using the knife for a little whittling, then sharpening again is what finally develops that perfect tool.
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Sharpening Round Gouge Honing Board
The Beginner’s Tool Kit
Your First Carving
Basics to Landscape Relief Carving
