We are always on the quest for the sharpest knife ever. Thinness of the blade, the texture of the blade face and the angle of the edge all affect the “Sharpness” or that amazing feel you get using a Japanese kitchen knife. It’s a feel that can redefine what you think sharp really means
Japanese knives stay sharper for a longer time because the are made with harder types of steel. The hardness allows for the edge to be sharpened at a smaller angle and sharpened to a finer finish. This means the edge is more like a razor and can retain that fine edge. The important thing to realize is that as hardness increases so does brittleness. This means you can chip the knife if it cuts hard objects, like bones, shells or ice. So on the quest for sharpness we are considering the knife’s toughness as well. Knife steel hardness is measured on the Rockwell C scale. The higher the number the harder it is, generally meaning the edge will stay sharper for longer, but will also be more brittle
Stainless steel was developed to inhibit the rust factor of traditional steel and originally it’s big issue was that it didn’t stay sharp. That issue has been getting better as steel alloys have developed. High Carbon Stainless Steel used in these knives is chosen for its edge performance, along with its stainless abilities. By some measure it still doesn’t stay as sharp as the carbon steel. If you don’t feel like you want to be drying your knife off constantly and dislike the idea of rust, then stainless may be your best choice. Just remember it is possible to make this rust if treated poorly, it is stainless, not stain never.
The knife makers steel of the moment. VG10 is strong, hard, stainless and relatively easy to sharpen. It is generally forge welded within softer stainless steels and tempered to 60:62 Rockwell. More and more manufacturers are using VG10 for their blades because of it’s user friendliness.
Powdered Stainless steel. This is the newest and best answer to corrosion resistance and edge retention. It is very fine material that allows for a beautifully sharp edge like carbon with the ease of stainless. It is much more difficult for the blacksmith to work with and can be challenging to sharpen.
These are serious precision instruments and must be treated as such. I would even say they need to be babied a bit. With these knives one must accept that the blade will chip from time to time, but it’s a small price to pay for the insane performance.
The original type of steel is referred to as “Carbon Steel” and has many benefits. It is relatively easy to sharpen, it can be easier for the blacksmith to forge, it holds it edge really well too.
This steel will discolour and develop a dark patina over time, but will rust if treated poorly. So use, wash and dry twice before storing. Maybe think about oiling the steel with camellia oil or a food grade mineral oil. Take care of these blades and they will repay you with years of cutting excellence.
White steel is the purest of the Carbon steels. The ingredients are Iron and Carbon (up to 2.7%). This is the easiest steel to sharpen and is capable of achieving the most perfect mirror finished edge. This steel has the ability of being forged to incredible hardness which translates to exceptional edge retention. Why do you think sword makers love this steel? Special care must be taken with Shiro-ko knives as they are the most reactive, however after a nice strong patina has formed on the blade they are less likely to rust. Patina is your friend.
Blue steel is basically Shiro-ko with the addition of chromium and tungsten. This additions increase the durability of the blade, reduce the reactivity of the steel and give the potential for longer edge retention. Ao-ko steel is not stainless, but tarnishes slower than Shiro-ko.
Often referred to as Yasuki #1 Blue Steel this is a great knife makers steel. It is hard, extremely easy to maintain, rust resistant (for carbon steel), capable of an outstanding mirror finish and long lived edge. What more can you want? This is high performance steel.
Blue #2 is the another great knife maker’s steel. Just as hard as #1, but tougher and more durable. Basically it is less likely to chip.
If you take the recipe for #1 or #2 and tweak it a bit you can make Super Blue steel. It has all the benefits of #1 or #2 and many say it performs better. Using both on a regular basis I would say they are quite similar and a bit different. I’m unable to make a judgement call on which is better. I know that the patina each steel achives is slightly different in colour. Both are great knife steels.