No matter how well manufactured or what kind of steel is used for a knife to be made, it will eventually become dull and will require resharpening. The frequency your knife requires maintenance is subjective and depends on its use (how often you use it, materials you cut, use of proper cutting surface etc).
What is honing & what’s the difference between sharpening and honing?
After sharpening, the first few times you use your knife, its edge starts to bend/fold one side or the other. With honing we realign that bended edge back to its straight position. Honing straightens the edge and does not meant to remove significant amount of steel. After some time, eventually the edge will become flatter (dull) and it will need sharpening ( steel removal) in order to create a new sharp edge (steeper apex). So, honing is used after the initial loss of the optimal cutting feeling, when the edge is folded (but not flattened) which is usually after the first times of use.
When honing doesn’t work anymore, it is time to move to sharpening in order to create new apex.
There are different types of honing rods:
- Steel – the most traditional type. Can be totally smooth or rigged. The steel hones are not recommended for Japanese knives as their steel is so hard they could chip on a steel hone.
- Diamond – The problem with diamond honing rods is that because of their hardness, they tend not only to realign the edge of your knife but aggressively sharpen the knife by violently removing metal. Usually in Japanese steels this does more bad than good as the honing procedure must be gentle.
- Ceramic – The best choice for straighten an edge. They are harder than knife steels and less aggressive than the diamond rods. They will remove some metal but with few strokes they will realign any folded edge. They need attention during use because they can break if they fall.
How to hone a knife
Place a dry towel on the kitchen top. Take the honing rod in your hand and nail the tip of the rod on the towel. With your other hand take your knife and GENTLY strop the knife with a steady backward AND downward motion on the one side. Continue with the other side and after 5-6 light strokes check if the edge realigned. You must maintain proper angle (that of the initial sharpening angle)
Things to watch out:
• Traditional handmade Japanese knives are very hard. Being hard means also brittle and prone to chipping therefore the only choice for these kind of knives should be a fine grit ceramic rod and the strength used during honing must be minimal.
• When you choose a honing rod, a longer one will give you more space to swipe your knife in one continuous and comfortable move.
• Ceramic rods, as any other honing rod, have to be cleaned after some time. To remove the metal flakes (swarf) off the rod use a specialized supereraser available in the site or put a small quantity of non reactive oil (oil that won’t go rancid) on a towel and wipe the rod up and down until the flakes are removed.
What is sharpening?
Sharpening is the process of removing steel off the edge of the knife by stroking it at a certain angle against a hard surface with the purpose to make that edge as thin as possible.
Depending on the dullness or the possible damage a knife has (chipping/ broken tip) the sharpener has to select the proper type of a hard surface to be used in order to achieve this task. The choice of the hardness of course depends on how dull is the knife.
There are different types of sharpening stones and they can be separated in two big categories:
Usually they come in three grits (add hypertext the size of the abrasive’s grain) ( coarse, medium and fine). They use oil or water as lubricant medium. The major problem with natural stones is that you never know the exact grit of the stone as it is a natural product and may vary, even in the same piece of sharpening stone. The most common types are:
- Novaculite (Arkansas stones)
- Japanese traditional stones
- Local traditional stones
- Ceramic Water stones (whetstones) – they’re called waterstones as water is used as a lubricant during use. They come in various grits from 120 to 30.000 grit. These are the most reliable and easy way to sharpen your knife.
- Diamond Stones – Tiny industrial diamond particles on a hard metal surface. These come in basic grits and they offer quick and aggressive steel removal. Handful when super wear resistant steels come to play.
The best way to sharpen a knife is synthetic or natural stones. The last years synthetic stones have overtaken the market as they are easy to use, have specific grits throughout the material and their cost is significant lower (ex a Japanese natural stone can cost anywhere from 400 to 1.000, not easy for the everyday knife user to acquire)
The materials commonly used in the manufacturing of synthetic stones are silicon carbide (SiC), alumimium oxide (corundum) and Zirconium Alumina. The particles of the abrasive material (grits) are bonded using binding agents. The binding agent usually is comprised of synthetic products such as: polyacrylates, polyvinyl alcohol or various synthetic resins but, natural products such as cellulose, wax, clay and even magnesium is used sometimes. Both the accuracy in the grit manufacturing and the binding agent used, are making all the difference and affect directly performance.
Synthetic water stones have to be soaked in water for 10-15 minutes to absorb water in order to properly work. Nowadays, there are also “ready to use” stones (called “splash ‘n go”) which do not require water soaking, just a splash of water!
There are many different synthetic stones manufacturers, with Japanese being again the leaders. Shapton and Suehiro Cerax stones are among the market leaders.
The final step of the sharpening process is stropping. Take your strop and make gentle long, continuous, backward (from edge to spine) strokes on the strop, making sure all the edge is covered. Change blade edge side after each stroke. The angle to make these strokes should be the same as the one used in sharpening in stones. Stropping will remove any possible burr left from your finishing stone, straighten the apex and further polish your edge. Be assured not to miss this step, it makes a lot of difference.
Stone holder to stabilize your stones during sharpening. There are many different types of stone holders in the market. Some stones come with their own holders but others don’t so a universal stone holder would be a good investment.
Lapping plate to flatten your stones. One of the most important factors for a successful sharpening is the absolute flatness of the stones. After several uses the stones tend to create concave surface as during sharpening some spots are used more than others. Lapping plates come again in different materials, shapes, sizes and grits. The ones considered to be the best are the diamond lapping plates as they are the most durable and fast of all others. They are costlier compared to others but they will last a lifetime. So, before each session make sure your stones are totally flat (you can use a ruler), otherwise use your lapping plate to restore them. (more details on how to flatten your stones using a lapping plate will follow later).
A leather strop – A strop is a surface that is used after the finest stone for the final stage of sharpening. The function of a strop is to realign the final edge, polish it and work off any remaining burr (a tiny piece of metal that remains attached to a knife’s edge. See more here).
Strops are usually made of leather although other materials can be used. Both suede and smooth leathers, technically known as flesh side and grain side, are used but the type of leather to use is a matter of preference.
Strops can be used as they are or by applying a honing compound (abrasive micro particles such as diamond particles). It is again matter of personal preference.
Sharpening pond – Is practically a rectangular large size plastic or metallic bucket used under your stone holder and stone. It is half filled with water and its purpose is to soak your stones before using them and to avoid spills on your counter. Most of them come with an a “sink bridge” (a stone holder) attached .
Nagura stone – an ultra-fine stone that is used to create an abrasive slurry on the surface of the synthetic waterstones which speeds up grinding and polishes the edge at the same time. It can be used for leveling stone but lapping plates are much quicker and produce better results.
Marker and pencil – The marker is to mark the edge in order to see the area you actually sharpen when hitting the stones. The pencil can be used to make cross line marks on the stones and after the lapping process to check for uneven spots (hollow spots will have still the pencil marks)
Water Sprayer – to be used for spraying the stones when they dry up.
How to Sharpen
Soak your stones. Most of the stones require a 10min soak in water (place them in a bucket) or until they stop bubbling. “ Splash n’ go” stones don’t need soaking!
Flatten your stones – The first thing you have to make sure is that your stones are perfectly flat (new or barely used stones don’t need flattening).
If you have doubts, take your stone and with a pencil you draw crossing lines all over the surface of the stone in a way that all your stone face is marked(see pic below).
Wet the stone beforehand and use your lapping plate ( in case you don’t have one, use the coarsest / lowest grit stone you have by rubbing them together, with a move forming an “8” number. You will observe that as the stones start flatten, the pencil lines start disappearing. Continue until all lines disappear and your stone is ready.
Select the stone grits to be used – The grit selection depends on the condition of your knife . Most of the sharpeners use a 3 stone sequence, others 4 or more. If your knife is in good condition, you don’t need to go below Grit 1000. If your knife is chipped or its profile needs to be reshaped / touched up, you may need to start as low as 400 or even 220. Grit 1000 is considered by most as the basic grit when the knife is in good condition. A common stone sequence is: 220 or 400 (if needed) – 1000 – 3000 – 5000 – 8000 for high polished edge finishing. Some may go further up to 10000 or 16000 but most professional sharpeners agree that for food preparation to go higher than 5000 makes no real difference. Of course there are many opinions and never ending discussion regarding grit selection and grit progression, all will work as long as you keep a logical grit progression step .
Start sharpening – First get in the right position. The sharpening stone should be at the level just above your waist. Depending if you re left or right handed, the equivalent foot should be a little bit to the back so gives you firm position and more freedom for your good arm to move back and forth.
Grab the knife with your good hand by its handle as close as possible to the blade, using almost what we call a “pinch grip”
There are dozens of sharpening techniques and variables to sharpening. How the knife should be held, the angle of the knife to the stone, change of the hand for opposite side of the knife, long or shorter strokes, how pressure to apply, push or pull sharpening and more…
There are thousands of articles and instructional videos you can watch and choose the one that makes the most sense to you and gives you the best results. There is no easy way in sharpening, trial and error is the best way to learn and so you better start practicing using your old, cheap knife (rather your precious Japanese one!)
Keep in mind that there is no wrong technique as long as you can make a straight and razor sharp edge!
And remember, the two most important things in sharpening are:
Keep a steady angle!
The angle of the knife to the stone must always be the same during your strokes and grit progression (the only reason to change your sharpening angle is for burr removal and it is done in the last stones on final strokes, but this is in advanced sharpening). The angle used in most Japanese knives is 8 to 12 degrees per side, while in western knives 15 to 20.
Watch for the burr – A burr is the deformation of metal at the apex of the cutting edge. It looks like a foil stuck on the edge and it is generated always during sharpening!
Burr creation and observation, lets you know when one side is sharpened and ready to switch sides. If a burr is not formed during the sharpening process then you either did not find the right angle for the sharpening or you did not sharpen it enough.
To feel the burr, gently and carefully move your thumb vertically (to the opposite side of the bevel you are sharpening) and check for that metal foil. In lower grits you will be able to feel it easily with your thumbnail or thumb where in higher grits it is not possible. When the burr is formed either change side or move to the next stone.
Important Note: The burr formation is directly related to the steel and its heat treatment. Hardest, high alloy steels are more difficult to create a burr and require more time as well as there are steels that have stubborn burr that doesn’t remove easily and thus don’t feel “sharp”.
Single Bevel Sharpening
Single bevel sharpening shares the same ideas with the double bevel ones, but it has some distinctive differences.
Firstly, let’s clear some things up: Single bevel knives have one part that looks flat and one side that is grinded in an angle to form the bevel. The “flat” side in reality is slightly concave (hollow) for better food release (the concave part is called Uraoshi).
The idea behind single bevel sharpening is to sharpen the grinded side using all the required grit process (from 400 or 1000 depending on the condition of the knife up to finishing stones to our liking – 5000, 8000 or even higher) and then finalize on the “flat” side with only a higher grit stone (5000 and up) just to remove the burr and make a polish.
Let’s see the steps in depth:
Start from the beveled side
The sharpening takes place below the point where the bevel starts (the Shinogi line) and has to be made in two parts: The first almost 2/3 upper part (from Shinogi line to lamination line- if it has one) with a slightly lower angle and by putting your fingers on the opposite side where the shinogi line starts. The reason for that is the following: When we sharpen the edge of the knife, we remove material. That means that after some time the angle of the final edge increases as the knife becomes thicker above the edge.
To retain the initial angle, we need to remove material also from above the edge and to move the shinogi line up at the same rate we move the edge up. That will retain the initial angle of the knife (12 to 16 degrees). In this first stage don’t expect to feel the burr as the part you are sharpening is not the edge. That will happen in the second stage.
The second stage is for the 1/3 lower part of the bevel (below the lamination line- if it has one- towards the edge called Kireha). Here we increase slightly the angle and we put pressure with our fingers at the lowest side of the flat side, close to the edge. Here the burr will be formed. When we feel the burr is formed and is even and consistent all the way through the edge, we move to our next stone grit.
Remember in both stages the angle has to remain steady during our back-and-forth strokes.
When you have reached about 5000 grit stone or higher in your sharpening process it’s time to sharpen the Uraoshi (flat) side. Here you put the knife fully flat on the whetstone and with the edge looking forward (not facing us). In this process is important to apply pressure to the knife by putting our fingers on the Shinogi line but only in the push moving strokes and not in the pull ones. The reason for that is that if we apply pressure in both, the top part close to the spine will be “trimmed” at a higher / faster rate from the edge part and will show uneven and over time the spine will be thinned and weakened.
Then we turn and do our highest grit finishing stone on the beveled side and we are done!
Microbevel formation can be the next step if we like. Microbevel formation advantages will be discussed in another article.
Related video is coming soon!