Sharpening Japanese Kitchen Knives and Woodworking Tools
So, you’ve made the decision to buy yourself a Japanese Kitchen Knife or one of the range of Japanese Woodworking tools, a Kana (plane) or a Nomi (chisel) etc. Having done that you now need to work out what is the best way to sharpen your new purchase as Japanese Steel products should really be sharpened using a Japanese sharpening product.
The trouble is there are quite a few options to choose from, Whetstones, Natural Sharpening Stones, Diamond Sharpening Plates, 2- or 3-wheel sharpener and ceramic or diamond Steels. Every one of these options has its place in the sharpening process and it comes down to deciding the best option for the product you have purchased.
In the past I was used to using oil stones and steels for sharpening knives, chisels & plane blades, sometimes even fine grinding wheels if they were chipped. These forms of sharpening should not be used with Japanese steel as it is harder and can be more brittle so using a grinding wheel will have a negative impact on the tensile strength of the steel, oil stones (another form of whetstone) are very slow due to the hardness of the Japanese steel and whilst you can use a Steel to touch up the edge it is recommended to use a ceramic steel.
Choosing the right Sharpener for You
When I first investigated the best methods for sharpening my Japanese Kitchen knives, I really wasn’t sure where to start. There is a lot of information to be found on the web and you find some particularly good YouTube videos from Knife Sharpeners like Burrfection and others.
My advice is to not overthink it and use the sharpening method used in Japan for centuries and that is a whetstone or more accurately a water stone. Sharpening your knives or tools by hand can be an enjoyable experience, especially when you get that razor sharp edge you are looking for.
Now you are thinking “I have never sharpened anything on a stone before, it looks far too hard, what if I ruin my knife or tool blade”. Don’t worry I was the same when I took to sharpening my Japanese Kitchen knives and these knives weren’t handmade knives, but superior quality Hand finished knives and I had previously sharpened a lot of European steel kitchen knives.
For me the most difficult part was getting used to sharpening the bevels at 15-16 degrees which is the angle most Japanese knives are sharpened at, I sharpen my knives at 14 degrees. Making yourself a guide solves that problem and if you are still concerned get a cheap kitchen knife to practice with first. I made a 14 degree guide out of rigid plastic and used a petty knife to practice with as it had the shortest blade.
I would recommend you start with a 1000 grit whetstone or if you are able to, buy a combination stone around the 1000/6000 grit as you can use the 6000 to give the knife a nice finish after using the 1000 grit side. If the stone doesn’t come with its own stand, I would suggest you also buy a stone holder and set up a bridge of some sort over your sink, so you have a ready supply of water.
Common Whetstone expressions –
- Hardness – A whetstones hardness is different to the grit. You can have a hard and a soft whetstone with the same grit level. Softer stones are recommended for beginners as they are more forgiving than harder stones, but the softer stones do wear more quickly. Once you are comfortable with sharpening you can investigate the harder stones, but it is not something that you should rush.
- Grit level – The grit level of a whetstone, like that of sandpaper, gives an indication of how abrasive the stone is. The lower the Grit number the more abrasive the stone, the higher the Grit number the finer the finish. There are 3 main grit levels for whetstones: -
- Coarse – This usually covers the 100 to 800 grit stones which are used for the removal of chips, getting an edge back on a knife or tool that is very blunt. The most important thing to remember is that the coarse stones remove material a lot faster than the medium or fine stones. However, it is important to use the coarse stones when the situation requires, or you will take a lot longer if you only use a medium stone.
- Medium – Stones in the 800-3000 grit range are considered medium grit stones. The medium stone is the go-to sharpening stone when you need to get a good edge back on your Japanese kitchen knife or woodworking tool. A 1000 grit stone is the most used stone in this grit range; however, you still need to be aware that these stones can remove a decent amount of material, so it is best to go slowly whilst learning.
- Fine or Finishing – Stones in the 3000-10,000 grit range are considered finishing stones. These stones are used to put the final finish on the knife/tool, 6000 grit and higher stones are used to get the extremely sharp edge and mirror finish. As a beginner a 6000-grit stone would give you a good finish but as you gain more experience an 8000 or even a 10,000-grit stone would be recommended.
If you can see yourself doing a lot of sharpening you would need at least 3 stones, or more depending on what you are sharpening.
Whetstone Types –
- Natural Whetstones – Originally sharpening was done with stones people collected off the ground and then natural stones were mined for a specific type of stone. Natural stones usually have a grit range, for example the Amakusa White stone has a grit range of 500-700 and is a medium to hard stone. Natural stones are said to be good for sharpening as they promote a longer lasting edge due to the grit range.
- A point of note is that a lot of Natural stones do not raise a good slurry so are not recommended for beginners, however, I have been using the Amakusa white stone since I started sharpening my Japanese knives and I have not found any issues with it aside from the time it takes to raise a slurry. I also use less pressure when using this stone as it does take material quite quickly.
- Synthetic Whetstones – The majority of Whetstones on the market today are manmade synthetic stones and these stones have the advantage of grit consistency and their price and availability. Synthetic Whetstones are made with bonded abrasives, for example the King Whetstones consist of aluminium oxide, carbide and nitride fused together and then mixed with a clay like bonder and baked at high temperatures.
- Ceramic Whetstones - like Naniwa and Shapton stones are stones where synthetic ceramic particles are combined, pressed, and fired to create the stone. The material used is commonly Zirconia dioxide which is mined and refined in Australia. Ceramic stones are harder than glass and they will become darker as they remove layers of steel from your knife or tools.
- Diamond Plates – Diamond plates are usually a block of Aluminium or steel impregnated with diamond chips or like the Atoma Diamond plates monocrystalline diamonds electro bonded to a thin sheet of stainless steel that is then mounted (stuck) to a 10mm thick aluminium block. The advantage of this type of plate is that the top sheet can be removed when worn and a new one attached to the original block. Diamond plates do tend to take more material when used for sharpening, however a lighter pressure can resolve this problem. Also, the coarser plates can be used to dress your other whetstones to keep them flat.
- Soaking vs Splash & Go – A lot of Japanese whetstones require soaking in water for 10 to 15 minutes prior to use as the stone absorbs the water and this helps to create the slurry required for sharpening. However, there are now some stones that do not require soaking as they do not absorb the water and these stones are commonly called Splash & Go stones. Both types of stones work as well as each other, however the drying time required for a soaking stone is a couple of days before you can store it away again. It is not recommended to leave your soaking atone in water for any length of time.
Summary – To summarise there are a lot of diverse types of sharpening stones to choose from and several different manufacturers. As a beginner you should look for a medium hardness combination stone or two separate stones in the 1000/6000 range, Splash & Go or soaking and once you have improved your sharpening skills look at the other options out there.
Other Sharpening Options –
- 2- or 3-Wheel Sharpeners – There are several types of these sharpeners available on the market, however, it is important that you only consider the ones made in Japan as they are set to the sharpening angle for Japanese Kitchen knives. Depending on the make of the sharpener you will find that they have a diamond wheel for very blunt knives and one or two ceramic wheels for finishing. When used correctly these sharpeners can give your knives a quick touch up when the edge starts to feel a bit blunt.
- I personally prefer these types of sharpeners to the different types of steels if I am not going to use my whetstones to sharpen the knives. However, I don’t usually use these sharpeners on my hand made kitchen knives, these I always sharpen on my whetstones.
- Steels – Typically you cannot use a regular honing rod on Japanese knives and the reason for this is the steel in the Japanese knives is harder than the steel in the honing rod. There is a misconception that honing rods sharpen the knife, in fact they do not, honing rods only realign the edge of the blade. The best options for Honing rods to realign Japanese kitchen knives are either Ceramic or Diamond.
- Ceramic honing rods- rods with extremely fine grits are the best choice for Japanese knives, you also want your honing steel to be longer that the knife you are realigning. You should also look for a Ceramic honing rod that has 2 grit options, for example a 1000 /2000 grit rod. The most important thing to remember when using the ceramic honing rod is that you maintain the correct angle of the blade to the rod for the full length of the knife blade. This is not always easy if you have not used a honing rod previously.
- Diamond honing rods – these types of honing rods are the most controversial as the diamond coating can remove substantial amounts of metal during the honing process. These honing rods should not be used for daily honing but using it occasionally can extend the periods between sharpening stone sessions.
My personal feeling regarding honing rods Is that they can harm the edge of your Japanese knife unless you are skilled in using one, this is due to the finer angle on the Japanese knife blades. I have found that when correctly sharpened my Japanese knives, both handmade and hand finished hold their edge much better than similar European knives and as a result only require a light touch-up on my 6000-grit Splash & Go stone to retain the edge I like.
Links to Sharpening Videos