There are a lot of things i hear on a daily basis from my customers or read online and every once in a while, i come across commonly misunderstood things or myths relating to japanese knives. I thought i'd start a thread where i can post things like that when i remember (or when someone asks me about them). If you have something to add, please feel free (just do a little fact checking first 
)...
so here we go...
Myth- Japanese single bevel knives have hollow ground edges because they are ground on big round wheels.
Truth- While the rough grinding is done on the large grinding wheels, much of the sharpening and finish sharpening is done on flat surfaces (like the waterwheel i have in my shop and also normal waterstones like you and i sharpen on). This doesnt mean that there cant be high and low spots. They can occur just the same (as they do on belt grinders with flat platens as well). No knives that i can think of off the top of my head are finished on the large wheels people always see in knife making videos. In fact, more often than not, knives are given convexed (or hamaguri) edges from the factory.
Myth- Japanese Single bevel knives need to have the bevels flattened and this is the way things are done in Japan.
Truth- ALL single bevel knives from japan (*that i know of or have seen),even cheap ones, have hamaguri edges. This doesnt mean that its always well done, and often times cheaper knives have poorly done ones. Even usuba and yanagiba. Its not just something done to strengthen an edge, but its also part of the way the knife interacts with food and food release. This is THE recommended way of sharpening single bevel knives by every japanese sharpening professional and/or knife maker that i have met. Flat ground bevels can sometimes be recommended to chefs to help keep things simple in their sharpening, but this is done with the understanding that they are sacrificing some of the performance aspects we look for from single bevel knives.
Myth (or misunderstanding or just cultural difference)- Microbevels are bad for your knife and an unnecessary sacrifice.
My opinion (cant really say truth on this one... its kind of subjective)- Americans (and many other western based cultures) tend to look for the maximum in things. Maximum sharpness, most acute angle a knife can hold, highest hrc, etc. However, you will see many chefs in Japan (the vast majority) use microbevels (koba) on their knives. They understand the small sacrifice in maximum potential sharpness is easily made up for by the increase in edge retention, increase in chip resistance, and ease in touching up the knife during a shift. This stands true for pretty much all single bevel knives i can think of- Usuba, Yanagiba, Deba, kiritsuke, etc. A lot of people seem to think this is just something for debas, but as it turns out its even more important on knives like usuba and yanagiba. Just remember, when you put on a microbevel, use light pressure and make sure to remove the burr.
What microbevels do is remove the very thin and brittle edge of the edge. This is one technique that can be used to get rid of wire edges.
Anyways, thats all for now. I'll probably add more later.
)...so here we go...
Myth- Japanese single bevel knives have hollow ground edges because they are ground on big round wheels.
Truth- While the rough grinding is done on the large grinding wheels, much of the sharpening and finish sharpening is done on flat surfaces (like the waterwheel i have in my shop and also normal waterstones like you and i sharpen on). This doesnt mean that there cant be high and low spots. They can occur just the same (as they do on belt grinders with flat platens as well). No knives that i can think of off the top of my head are finished on the large wheels people always see in knife making videos. In fact, more often than not, knives are given convexed (or hamaguri) edges from the factory.
Myth- Japanese Single bevel knives need to have the bevels flattened and this is the way things are done in Japan.
Truth- ALL single bevel knives from japan (*that i know of or have seen),even cheap ones, have hamaguri edges. This doesnt mean that its always well done, and often times cheaper knives have poorly done ones. Even usuba and yanagiba. Its not just something done to strengthen an edge, but its also part of the way the knife interacts with food and food release. This is THE recommended way of sharpening single bevel knives by every japanese sharpening professional and/or knife maker that i have met. Flat ground bevels can sometimes be recommended to chefs to help keep things simple in their sharpening, but this is done with the understanding that they are sacrificing some of the performance aspects we look for from single bevel knives.
Myth (or misunderstanding or just cultural difference)- Microbevels are bad for your knife and an unnecessary sacrifice.
My opinion (cant really say truth on this one... its kind of subjective)- Americans (and many other western based cultures) tend to look for the maximum in things. Maximum sharpness, most acute angle a knife can hold, highest hrc, etc. However, you will see many chefs in Japan (the vast majority) use microbevels (koba) on their knives. They understand the small sacrifice in maximum potential sharpness is easily made up for by the increase in edge retention, increase in chip resistance, and ease in touching up the knife during a shift. This stands true for pretty much all single bevel knives i can think of- Usuba, Yanagiba, Deba, kiritsuke, etc. A lot of people seem to think this is just something for debas, but as it turns out its even more important on knives like usuba and yanagiba. Just remember, when you put on a microbevel, use light pressure and make sure to remove the burr.
What microbevels do is remove the very thin and brittle edge of the edge. This is one technique that can be used to get rid of wire edges.
Anyways, thats all for now. I'll probably add more later.
