Understanding Knife Serration

It's critical to understand that all your kitchen knives are serrated. This is the very first thing you should understand if you plan on sharpening using any method. Every kitchen knife whether it be a petty, chef's, yanagiba or gyuto is serrated. You just can't see them clearly. That is how a knife cuts into food. The distance and consistency between these serrations will determine your "bite".

This is how your edge will look like magnified on a microscope.

I like my knives on the aggressive side. I like to feel it grabbing unto my fingertips as if it climbs every line on your finger print. This can be achieved with a lot of sharpening methods. Others would like a more refined edge, meaning they like the serrations not too far apart from each other. This, on the other hand, requires sharpening on a much finer grit stone. The higher the grit, the closer the serrations are to each other.

Some would argue that the best grit to use for chef's knives or gyutos would be around 1000-3000. That would leave you with a fairly aggressive bite that would grab and penetrate the skin of a tomato easily. But, if you were to slice delicate fish, sashimi for example, your knife won't be able to produce a clean slice. Since they are far apart, the serrations on your knife would crumple the fibers of the protein. You can still serve it and it would still be nice though.

However, it will not be anywhere near as nice as a yanagiba that's sharpened at an 8000 grit stone. It's the reason why sushi chefs sharpen slicers at a higher grit because then the fibers of proteins that they spend a lot of money on, won't be damaged. Imagine using a real serrated bread knife versus a regular knife on meat to blow it out of proportion.

Having said that, sharpening on a whetstone is somewhat determined by a "bite" preference (that is, if you're pushing it to the next level).

When you use your knife for an extended amount of time, it will naturally become dull. The longevity of your knife's edge is determined by a lot of factors: usage, kind of steel, tempering, heat treat, serration and etc.

This is your knife when almost all serrations are gone (dull).

It is said that natural stones provide the longest edge life to a blade. The reason being is that it gives the most uneven hight serration on the knife. This is because a natural stone that is mined will have a much random layer formation than a stone that is made synthetically. That means the length of the blade's edge won't dull all at the same time. Because it is uneven, the higher serrations would become dull first before the ones closest to the spine.

This is the edge when sharpened.

Once you understand knife serration you get the idea of what stones you might need in order to sharpen your knives or what techniques you want to apply. In time you will  also be able to determine what direction your serrations will face. You will also be able to distinguish how sharp or dull your knife has become.